TBC Brands, one of the largest distributors of private brand tires in North America, introduces the successor to the HTR Z3, the Sumitomo HTR Z5, which outperforms its predecessor with major improvements in wet braking, wet handling, dry braking and ride comfort.
The Z5 provides drivers of modern sports cars and performance sedans responsive high-speed handling with free defect replacement for the life of its usable tread. The tire features widened circumferential grooves for advanced hydroplaning resistance and an increased shoulder and contact patch to prevent irregular wear. This maximum performance summer tire is available in 54 Y-rated sizes with rims ranging from 17” to 20”.
“The HTR Z5’s size lineup captures the trend and popularity amongst the 18+ inch fitments as the market continues to shift toward larger diameters,” said Jon Vance, Senior Vice President of Product Marketing for TBC Corporation. “This tire is a great addition to Sumitomo’s full product line-up offering dealers a high-value, high-profit alternative to higher priced top and mid-tier products.”
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TBC Brands introduces the Sumitomo HTR Z5 tire
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Red Line Synthetic Oil’s additives and brake fluid ensure vehicles are performing at their peak
In addition to the company’s renowned motor and gear oils, Red Line Synthetic Oil, a leading manufacturer of performance lubricants, has a number of fluids and additives to keep brake, cooling and fuel systems performing at their best. These products include the company’s RL-600 brake fluid, WaterWetter and SI-1 Fuel System Cleaner.
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“Here at Red Line, we’re known for our high-quality motor and gear oils, but we also have one of the best high-performance brake fluids and a full line of performance additives that are some of the best in the world,” said Michael Andrew, Director at Red Line Synthetic Oil. “We believe our customers’ vehicles should perform at their maximum potential, from the brake system to the engine, and our entire product line is dedicated to this pursuit.”
A properly maintained brake system is extremely important for both safety and performance. Repeated hard stops generate heat and place the brake fluid under immense pressure, both of which are detrimental to the operation of the brakes, often leading to brake fade. With a dry boiling point of 604 degrees Fahrenheit (318° C), Red Line’s RL-600 Brake Fluid is a DOT4 fluid developed to resist these issues and maintain lubricity, compressibility and viscosity under even the most extreme conditions. Additionally, brake fluids are subject to moisture absorption which can reduce the fluid’s wet boiling point, lowering the brakes’ overall effectiveness. Red Line’s RL-600 combats this problem with its use of components designed to reduce moisture absorption.
In hot weather or under extreme track use, coolant temperatures can rise considerably, causing overheating and potential engine damage. By lowering the surface tension of water, Red Line’s famous WaterWetter® has proven to lower engine temperatures by up to 20°F, allowing for greater heat transfer from the engine’s metal components to the coolant. This method reduces the chances of overheating and the formation of harmful cylinder head hot spots, while also protecting against corrosion by forming a protective film inside these parts.
WaterWetter doubles the efficiency of water and provides crucial rust and corrosion protection in water only cooling systems. As an added benefit, WaterWetter may also allow for more spark advance and subsequently increased torque. Street cars using 50/50 ethylene or propylene glycol/water solutions benefit from the use of WaterWetter’s cooling power even under normal driving conditions, such as stop and go traffic, which can overburden a vehicle’s cooling system and cause overheating.
Vehicle’s fuel systems are often overlooked because standard maintenance intervals can be lengthy and the work itself can be time consuming and expensive. Due to inadequate octane capacity on the part of modern oil refineries, additives to pump gasoline often have a negative effect on vehicle engines by choking fuel injector tips with deposits, causing the engine’s fuel economy and overall performance to suffer. These deposits can occur in just a few thousand miles. In order to return engines to peak performance, Red Line created SI-1® Complete Fuel System Cleaner designed to clean injector tips and eliminate harmful lean misfires. Approved for use in both fuel-injected and carbureted gas engines, users can simply pour the product into their gas tanks, no mechanic required.
Since the beginning, Red Line Synthetic Oil has created products for racing applications with the idea that racers require the best of the best. This philosophy of creating the most advanced lubricants has become a pillar of the brand, not just within its racing line, but with all of its product offerings. Red Line creates its synthetic oils and advanced additives using the world’s finest base stocks, so consumers can rest assured their vehicles are receiving only the highest quality fluids.
For more information on Red Line Synthetic Oil, please visit www.redlineoil.com or follow Red Line Synthetic Oil on Instagram, Facebook or LinkedIn.
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Auto repair lessons learned in a minute
As I write this, I'm in the process of producing our 20th "Mighty Minute" — a video tech series sponsored by our good friends at Mighty Auto Parts. Each video is limited to four minutes in length and those of you who know me, know that it has been a challenge to stay under that limit especially as I dive into each topic and learn more about it.
The neat thing about this series is the foundational content it is made of. We rarely, if ever, get into the advanced stuff here because the series is produced to help techs who are just getting their feet wet. They are also designed to help techs explain, in simple terms, why a recommended service or repair (related to that week's topic) is needed.
Along the way, I get the chance to interact and learn from experts in each topic. So far, I've produced videos (all of which can be seen on our Motor Age YouTube channel) covering serpentine belt service, cooling system service, brake service, A/C testing and leak detection and more. While I thought I knew enough to easily produce four minutes’ worth of video, the experience has shown me that I, even after 40+ years in the business, can still learn something new.
Allow me to share with you a few lessons I've learned. Who knows? You may learn something too!
The importance of the serpentine belt
I'm just as guilty as I think many of you are when it comes to checking the condition of the serpentine belt. I take a look to see if there are any visual indications of wear and maybe even give it a tug or poke to see how tight it feels. After that, and if it isn't making any noise, I'm done!
But I learned that the serp belt plays a vital role that I'd been overlooking. It is responsible for funneling power from the engine to all the accessory drives connected to it; the alternator, the power steering pump, the air conditioning compressor and sometimes, the water pump. Any slippage that occurs between the belt and its pulleys generates excessive heat and that can occur even if the belt is running quietly.
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| One of the least expensive tools you'll ever add to your tool box, the serp belt gauge is the best way to properly verify a belt's condition. |
This excessive heat is passed on to these components - to their bearings, specifically - accelerating the wear and leading to premature failure. What's costlier? A new belt and tensioner or a new alternator or A/C compressor?
I also learned that belts made for the last 20+ years can be worn out yet show no visual signs of damage. The only correct way to inspect them is through the use of a belt gauge, a small plastic gauge that every major belt manufacturer makes a version of. If you don't have one, ask your parts house. I'm betting they have a whole box in the back!
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| With the tool square and perpendicular to the belt, you should see light between the gauge and the top of the belt ribs. The belt on the left (2A) is serviceable. The one on the right (2B) is not. |
Clean air for the engine
Dirt is a major enemy of the engine. When you consider how small the clearances are on today's powerplants, even the smallest visible dirt particles can cause major wear and tear if allowed in. So how do you know when the air filter on your customer's car needs to be replaced?
The answer I got was surprisingly unsatisfying. Ford, on some of their vehicles, used an airflow gauge to help determine when the air filter was restricted to the point of requiring replacement. And the engineers I spoke with told me they determined replacement by using expensive scales to actually measure the weight of the filter. Not very practical for every day, in the shop, use!
They did agree, though, that a simple "drop test" can provide some indication of how dirty a filter is. Simply drop the filter from waist height onto a clean rag and if you see dirt on the rag, replace the filter. Of course, if you can see visually that the filter element is damaged, has gotten wet, or contaminated with blow-by, there's no need to do the "drop test!"
So far, nothing to new, right?
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| Would you replace this filter? Be sure to inspect the condition of its seal as well as the condition of its filter element before making that call. |
I also learned that one commonly overlooked item is the condition of the filter's seal. Damaged or torn seals provide an alternate path for dirt to enter the engine. Additionally, warped or damaged air boxes can do the same thing, allowing dirt to bypass the filter element. If the box is damaged, replace it as well.
Clean air for the occupants
If the engine needs clean air to survive, how important is it for the vehicle's occupants to have clean air! Vehicles have been sealed tight for decades now to keep the road noise out but it also keeps the stale air in. Some estimates say that pollutants in the air of a typical automotive cabin can be 6x more concentrated than the air outside the vehicle!
And cabin filters need more frequent service, with most OEMs recommending service intervals of 15,000 miles or one year, whichever occurs first. If checking these filters, or at least offering to check these filters, for your customer for this reason alone is not enough, consider a few more.
Restricted filters will impact HVAC operation and component life. If the filter becomes restricted, the blower motor has to work harder to draw air through it and that can overheat the motor, resulting in early failure. It can also reduce airflow through the HVAC system, resulting in customer complaints of "A/C isn't blowing cold enough".
So help your customer breathe a little easier. Explain the importance of the cabin air filter to them and offer to inspect or service it for them when they come in for any routine maintenance service.
Additive packages
One topic I covered as part of the "Mighty Minute" series was coolant testing and service, and it's a topic I've covered a few times because it is so important to the health and longevity of the engine. I've also touched on this when it comes to engine oil and brake fluid.
The topic? Inspecting and testing the health of the fluid's additive package.
All these fluids have some kind of added chemical package designed to protect the base fluid from premature breakdown. When these additives are depleted, their protection is no longer there and the base fluid will quickly deteriorate and be unable to perform its role.
Coolants and engine oil have it harder than the brake fluid, I think, with many more factors that come into play that can cause the additives to become depleted early. Just because the bottle says it's a "lifetime" coolant, don't believe it! The coolant may last a lifetime but the additives won't, and if subjected to contamination from cylinder head gasket leakage or stray electrical current, the coolant may only last a few months before it requires replacement.
So how do you accurately test the coolant's additive package? By using a specialized test strip that measures the pH, or acidity, of the coolant. As the additives go away, coolant becomes more acidic and that's what accelerates the wear on the cooling system's various components - from water jacket plugs to water pump impellers.
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| pH test strips are the way to go to inspect the condition of the coolant and the brake fluid - both become acidic as the additive packages they contain become depleted. |
As for brake fluid, we used to focus on water content. We all know that brake fluid is hygroscopic; that is, it can absorb water right out of the surrounding air, and that water contamination can lead to reduced boiling points. Not good for a fluid that plays so closely to components that generate a ton of heat!
And while moisture content is still a valid test, the focus shifted some time ago to the copper content in the fluid. Why?
The additive package, that's why. Or more precisely, the lack of one. As the additives depleted, corrosion inside the system would cause the copper coating on the interior of the metal brake lines to flake off and collect in the fluid. The amount of copper was an indication of the health of the additives, and in turn, the health of the brake fluid.
If we found high copper content, we recommended a brake fluid exchange to clean out the system and replace the old fluid with new.
And we flushed all the copper out at the same time. So NOW, if we test for copper content on a system that has been cleaned once already, there will be no indicators to help us judge the health of the brake fluid!
Thankfully, there are smarter guys than me on the problem. They discovered that, like the engine coolant, as the additives were depleted the fluid became more acidic. Now the BEST way to test brake fluid is to measure the pH of the fluid using specialized test strips you can get from your local parts supplier.
As for the engine oil
I don't know of any test strips for the engine oil to help assess the condition of its additive package but acidity is not the primary reason we need to change it regularly. No, it's to help flush out the contaminants that have collected there, the ones the filter was unable to collect.
And that's probably the biggest lesson I learned more recently. We all know how important it is to use the right oil for the application, right? (I hope everyone reading this does, anyway!)
But do you give the same consideration to the filter you're using on your customer's car? As I said in "The Trainer" video, it's been my experience that expensive doesn't always mean good but cheap is ALWAYS cheap!
The filter is responsible for catching as much of the debris from the oil as possible and a good filter will trap 99% of the debris down to 10 - 15 microns in size (that's really small!). The second factor to consider is how much the filter can hold. Changing your customer over to synthetic oil and doubling the service interval from 7,500 miles to 15,000 is not doing him any favors if the filter plugs up at the 5,000 mile mark and the internal bypass valve opens!
One more factor I like to consider is the quality of the construction. Does the filter have a good anti-drainback valve that will keep the filter full and prevent the dirty oil its holding from draining back into the crankcase on shutdown? Does it use an efficient filter element supported by metal ends or is cardboard used instead?
I actually cut a few name brand filters apart to see what they were made of and the results were, let's say, enlightening! Just because they have a big ad budget and an attractive spokesperson doesn't mean the filter will meet the task.
There's a lot more I could share but that's all the room I have this month. I'm hoping you took away something new from this just as I did working on these projects. If you did, be sure to check out the "Mighty Minute" and "The Trainer" series on our YouTube channel!
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Learning the value of fuel trims
Most of us as technicians know that fuel trims are part of the ECM (Engine Control Module) data stream that we can access with our scan tools. However, a lot of techs either struggle with or fall short of using fuel trims to their full diagnostic value. This article will explain fuel trims and expand on how we can employ them as part of our regular diagnostic routine to increase our diagnostic efficiency and accuracy.
What are fuel trims?
What are fuel trims and why were the originally added to the ECM’s data stream? Fuel trims were a mandated OBDII Parameter ID (or PID) that reflected the ECM’s correction to the injectors base pulse width (IPW) to achieve a desired air fuel ratio (AFR) based on the oxygen sensor and other engine sensors input to the ECM in closed loop. In layman’s terms, they were a feedback loop system that was developed to use an “if /then” strategy for fuel control to the engine. But why? Why did we have to have this strategy? A big factor to their development was the adoption of the three-way catalytic converter or TWCC.
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| Any air that enters the engine without passing through the MAF sensor first will create a "lean" condition. |
TWCC’s required the feed gases to be close to Stoichiometric (14.7:1) air-fuel ratio to function at their greatest efficiency. Using the closed loop feedback system helped to achieve this. Most techs realize that fuel trims and the O2 sensors work in tandem with one another. So, if the O2 sensor reports too lean of a condition in closed loop, the ECM will make a correction to “fatten up” or add more fuel to the engine. Conversely, if the O2 reports to the ECM that the exhaust is too rich, the ECM will make a correction to “lean out” or subtract fuel from the air fuel ration entering the engine.
An example of a simple feedback loop would be a modern HVAC thermostat on the wall of your home that is capable of both cooling and heating. Let’s say it’s set at 70 degrees F. It’s chilly in your home in the morning and the room’s ambient temperature is 60 degrees F. The thermostat senses that “there isn’t enough heat” and tells the furnace to “add 10 degrees of heat” until the 70 degree F mark is met. If later in the day, the house heats up to 80 degrees F, the thermostat senses this and signals the A/C system to “remove 10 degrees of heat” until a desired temperature of 70 degrees F is attained. The thermostat would be the input that is responsible for the “if” part of the “if-then” equation. The HVAC unit would be the “then” part. The intelligent circuit board in the HVAC unit would be analogous the ECM.
From OBDI confusion to OBDII clarity
Fuel trims have been around since the early years of self-diagnostics in OBDI vehicles. In the old GM OBDI world, there were the fuel control PIDs called Block Learn and Integrator. GM used a sliding scale between 0 and 256 with 128 being the center point. If the number was greater than 128, it reflected the amount of enrichment that the ECM commanded to compensate for a lean condition. If the Integrator read 139, the ECM had sensed the engine was 11 percent lean and made the appropriate correction. In addition, if the Integrator PID in the scan tool’s data stream read 120, it is reflecting the ECM sensing the exhaust is too rich and it made the appropriate correction to subtract 8 percent fuel to lean out or bring the Integrator back closer to 128 or the zero mark. The Integrator revealed the ECM's quick response where the Block Learn was the learned value that accumulated over time and learned the trends or cells for the Integrator corrections. Back in the day, I always struggled to remember which PID was which. Manufacturers could use any term they wished back then to describe the ECM’s correction.
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| A restricted exhaust on one side of a dual exhaust system can cause an imbalance of fuel trim between banks. Look at the bank with the more negative correction for the cause. |
Fast forward to OBDII and now OEMs are required to call the real time correction Short Term Fuel Trim or STFT. The learned value now had to be called Long Term Fuel Trim or LTFT. The correction is now also required to be displayed on the scan tool in the form of a percentage. Positive percentages reflect the percentage of correction when the ECM is adding fuel to correct for a lean condition. Negative percentages now reflect the percent of fuel that is being subtracted to correct for a rich condition.
Fuel trim response to common problems
Using the scan tool's ability to graph PIDs like Short Term Fuel Trim can be a great asset when diagnosing drivability issues such as air metering issues, vacuum leaks, fuel delivery and volumetric efficiency issues. They give the tech the ability to see the ECM corrections to the problems listed above and aids techs in a getting diagnostic direction.
Vacuum leaks—Let's say the vehicle has vacuum leak. On a MAF-equipped vehicle, this means it has air that is entering the engine that is not being measured by the Mass Air Flow sensor. Most of us know that the air-fuel mixture is based on the amount of air entering the engine on a vehicle that has a MAF. If unmetered (often known as pirate or false air) enters the engine from a breach like a leaking intake manifold gasket, the ECM does not deliver enough fuel to achieve the proper air-fuel ratio (AFR). This results in a lean condition which is observed by the oxygen sensor. The ECM, if in closed loop, will make the corresponding if /then correction to STFT (Short Term Fuel Trim) and will add additional fuel to try to achieve stoichiometry.
The largest percentage of the breach or vacuum leak occurs at idle. This is because the throttle blade acts as a restriction to airflow. As the throttle blade is opened, the size of the breach or leak is diminished due to the fact the throttle blade's restriction has been removed and manifold vacuum is replaced by atmospheric pressure under wide open throttle acceleration. From a diagnostic standpoint, our fuel trims will reflect this. If we graph the STFT correction, we would see high positive fuel trim corrections at idle that waned a way closer to 0 when the throttle blade was opened.
MAF input error — Let's say we suspected the MAF sensor was not reporting the correct amount of air entering the engine. How would we expect our fuel trims to behave?
An example of this could be a MAF hot wire that is covered up with debris, oil or just a failing MAF sensor. Since most Mass Air Flow failures tend to overestimate air flow at idle and underestimate air flow under acceleration or load, we would see slightly negative fuel trims at idle and the more we opened the throttle blade, the more positive the fuel trims would react. Techs often notice that the positive fuel trims tend to “follow the throttle” when this problem is present.
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| A failing or contaminated MAF sensor will often cause negative fuel trims at idle and progressively more positive fuel trims as engine speed and/or load increase. |
Bank-to-bank imbalance— Fuel trims can also be a great aid in diagnosing bank-to-bank air imbalance issues, especially on MAF-equipped engines. The bank-to-bank imbalance in airflow is usually caused by a problem with the engine’s Volumetric Efficiency (VE) or, in simpler terms, its ability to inhale and exhale. This can be caused by restrictions hampering the engine ‘s ability to breathe or a cam timing issue on a V-configured OHC motor that use separate camshafts for each bank.
How do you suspect the fuel trims to behave on an engine when such a bank-to-bank airflow imbalance is present? The answer would be it depends. It would be dependent on a couple of factors: the amount of the imbalance in airflow bank-to-bank, the engine RPM and load and the degree of restriction present for starters. A general statement would be that when bank-to-bank airflow imbalance is present, the fuel trims are usually opposed — in other words, there is a significant difference side-to-side, sometimes techs refer to this as the fuel trims are skewed bank to bank.
Think about why this happens. As an example, let’s look at a MAF equipped V-6 where each head has its own camshaft and its own pre- and post- O2 sensors on each bank. The MAF sensor’s job is to measure the air entering the engine and report it to the ECM so it can add the correct amount of fuel to the engine to try to maintain stoichiometry of 14.7 to 1 air-fuel ratio. Let’s say at a steady state throttle opening, the MAF sensor reads and reports that 48 grams of air per second (gps) is entering the engine. The ECM in closed loop is going to provide enough fuel for each cylinder to have the correct amount for 8 grams of airflow per cylinder (48/gps of measured airflow/6 cylinders = 8/gps of airflow per cylinder).
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| Misfires can be caused by ignition or fuel delivery issues. Fuel trims may help point you in the right direction. |
What if the same v-6 engine has an exhaust that incorporates catalytic converters for each bank and one side is restricted? How are the engine fuel trims going to appear and why?
For example, say the same engine under the same conditions that would normally report 48/gps of MAF has an exhaust restricted on bank 1 and only reads and reports 6/gps per cylinder due to the Bank 1 exhaust restriction. Bank 2’s VE or breathing is unaffected and still pulls 8/gps per cylinder. So, what does the MAF report to the ECM?
Answer: Bank 1 has 3 cylinders @ 6/gps = 18/gps and Bank 2 has 3 cylinders @ 8/gps = 24/gps. The MAF now reports 42/gps (B1 18 + B2 24) to the ECM. The ECM sees this and assumes that each cylinder should get the same amount of fuel for the 7/gps of airflow per cylinder (42/gps divided by 6 cylinders = 7/gps per cylinder). Most vehicles only have one MAF sensor that is centrally located in the intake tract so it cannot differentiate between each bank’s VE. The unaffected or normally breathing side (Bank 2) gets delivered fuel for 7/gps of airflow delivered to cylinders that actually flow 8/gps. These cylinders are now under fueled and lean.
The oxygen sensor on that bank reports this to the ECM which, in closed loop, counters by adding more fuel through a change to that side of the engine's injector pulse width (IPW). This is reflected in the fuel trims for Bank 2 reading positive. Now let’s examine bank 1, the side with the exhaust restriction.
Bank 1 Volumetric Efficiency has been altered by the exhaust restriction, in this example the Bank 1 Cat is damaged. The cylinders that should be flowing 8/gps are now only flowing 6/gps due to the restriction. This changes the MAF reading and because the MAF can’t differentiate between each bank,s airflow, Bank 1 now receives fuel for 7/gps for cylinders that are only flowing 6/gps. The result is that Bank 1 is over fueled and is now running richer than it should. Consequentially, the Bank 1 O2 reads rich. The ECM sees this and, if in closed loop, subtracts fuel by reducing the Bank 1 cylinders IPW. This is reflecting in the scan data for Bank 1, now showing negative fuel trims.
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| The MAF reports total air entering the engine — something that doesn't change whether it's ignited or not. |
So, when we have a vehicle that has catalytic converters and oxygen sensors on each bank and a restriction in the exhaust occurs, the fuel trims will be opposed from one bank to the other. The question diagnostically is when we have opposed fuel trims which side do we diagnose? The above example hopefully illustrated that we examine the side or bank with the most negative fuel trims.
We could also have a similar situation where the trims are opposed bank-to-bank caused by an airflow imbalance that is not caused by a restriction, but rather by a Volumetric Efficiency issue caused by valve timing — the valve timing is off. Let's say we had an overhead cam engine that was a V-6 and each cylinder head had its own camshaft. Moreover, the scan data revealed while in closed loop the fuel trims for bank 1 were +3 percent and the fuel trims for bank 2 were +22 percent. Which side of the engine has the most negative fuel trims? If your answer was Bank 1, you are correct. Bank 1 is the side that has the air flow imbalance.
Misfire— Fuel trims can be help us determine whether a misfire is fuel-related or ignition-related. For example, if I have a 4-cylinder engine that is misfiring and I have already ruled out a mechanical issue using a relative compression test or a cranking vacuum transducer test, my next suspect will be either fuel or ignition.
If I had a fuel injector that the wiring harness had rodent damage and caused an injector to be electrically offline, how would that affect my oxygen sensor readings? The answer would be 02 would read lean due to the fact the ECM could not deliver enough fuel to the engine. Obviously if the oxygen sensor told the ECM it was too lean my fuel trims would be positive. The question is how positive would they be?
Let's examine this. So, if the rodent damage was done to a single injector, and the ECM attempted to inject the correct amount of fuel into the cylinders but couldn't due to the wiring harness damage, how much of the fuel got delivered to the engine? If you said 75 percent, you are correct. If the above vehicle is misfiring and the ECM shows that the oxygen sensor is still lean it will try to compensate in closed loop by adding positive fuel trims close to +25 percent.
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| A failed injector, however, doesn't deliver its share of fuel to the cylinder its assigned to, and results in less fuel overall for the amount of air reported to the ECM. |
So diagnostically, if I have a misfiring vehicle that has high positive fuel trims in a single cylinder misfire, I might want to examine fuel injection for that cylinder. Consequently, if I have a vehicle that has a misfiring cylinder and my fuel trims appear to be normal, I am going to look into ignition as the probable cause. It has been discussed in previous articles how ignition misfires have very little effect on fuel trims in closed loop.
Let ‘s review, fuel trims have been around for a long time, basically since the ECM took over fuel control via a feedback loop. OEMs got to call it whatever they wanted and use however they chose. OBDII changed this. Now it is a mandated PID in the data stream. They have to now be referred to as short term and long term and given in percentages. Positive percentages indicate the ECM’s correction for a lean exhaust by adding fuel. Conversely negative fuel trims indicate the ECM correction for rich exhaust content by subtracting fuel. Graphing scan data on MAF can be very helpful for diagnosing lean conditions like vacuum leaks and air metering issues. Opposed fuel trims bank to bank indicate an air flow imbalance bank to bank. When trims are opposed look to the side with the most negative trim as the side with the issue. Moreover, fuel trims can be used to differentiate whether a misfiring cylinder and ignition or fuel related. Hopefully this article gave you some insights regarding using fuel trims as a diagnostic aid.
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Understanding Toyota's vehicle control history
The Toyota Techstream scan tool offers technicians the ability to access an amazing wealth of information from vehicle electronic control units. On newer model Toyota and Lexus vehicles, the ability to access Toyota Vehicle Control History VCH) information is a valuable tool in no-code diagnostics. The VCH data also provides some incredible diagnostic data for technologically advanced systems such as Toyota safety sense.s
The first time I ever attended a factory Toyota course, the instructor got on the subject of what he described as a black box technology, similar to that of today’s commercial airplanes, that store relevant data related to a crash should one occur. This black box data was only accessible via a Toyota field engineer and was not accessible through a scan tool. I can remember thinking how nice it would be if that data was actually available to technicians in some form as there are many times as technicians that we just simply don’t have enough information to properly diagnose and repair a vehicle. Fast-forward ten years and the idea of accessing ECU data that is not associated with a DTC is now becoming a reality on Toyota and Lexus Vehicles.
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| Vehicle Control History provides Engine Control “X” codes without setting a DTC – a great resource for no-code diagnostics. |
Toyota has utilized Event Data Recorders (EDR) since 2000 when it began a rollout across the product line. Today, approximately seventy percent of the Toyota’s in the US are equipped with this technology- the subject of a 2016 Society of Automotive Engineers white Paper entitled Event Data Recorder Developed by Toyota Motor Corporation. The Toyota Event Data Recorder was developed to collect several collision analysis data parameters including pre-crash, side crash, rollover and pop-up hood pedestrian data. In addition to these parameters, Toyota also collected Vehicle control history data in a non-crash, triggered recording system. Federal regulations stipulate that this data must be available via a commercially available tool and Toyota worked with Bosch to utilize the crash data retrieval tool or CDR. Recently, Toyota began making some of the data available via their Techstream scan tool.
In the aforementioned white paper, Toyota stated that they felt that the evolution of this technology was forthcoming. For us as technicians, this is just the tip of the iceberg into how this data might help us.
HV operation history
Imagine yourself as a service advisor at a Toyota dealership in a busy metropolitan area in which a car count of over 100 vehicles is a normal day. Toyota has just announced a new model of the Prius and over twenty of these vehicles were delivered this week alone. The shifter technology has changed from previous model years and now includes a joystick shift function that is difficult to operate for some customers. After delivering the new vehicles to the customers, several have come back to the service drive complaining of transmission and shift related issues. The technician assigned to the repair order test drove the vehicle and found it to be operating normally and upon performing a Techstream health check there were no diagnostic trouble codes found in any of the modules. The service advisor reported the lack of findings back to the customer who is now displeased with the product and the dealership because the experience they had was perceived as a problem. In reality there may have been an error on the part of the customer in operating the vehicle.
The above scenario is a perfect example of how EDR data could be potentially used. In the past we have relied on a DTC in order to have a diagnostic game plan. A DTC gave us a code-set criteria and also brought with it freeze frame data. However, when a DTC did not set, we were forced to try to duplicate the concern. Duplication of a customer concern can be a wild goose chase that often results in the famous “no problem found” report back to the customer.
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| A Group 2 VCH Data capture displays twelve distinct freeze frame data points before during and after a triggered VCH event. |
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| A group 3 VCH Data capture reveals slightly less information than a group 2 while a group 5 will store only one data point. |
In 2015 when the 4th generation Prius was introduced; Toyota also included some enhanced scan tool functionality known as HV Operation History. This function allows the technician to access some very interesting data from the data list within the hybrid control ECU. This data is of particular interest when a scenario like the above-mentioned shift concern or in the event of an inability to ready on occurs combined with no DTC’s present. Specifically, the Techstream software is looking for abnormalities in driving conditions or other non-driving abnormalities that it sees as an issue but would not set a code for.
The beauty of this information is that it is referenced to a point in time within the data list. The HV operation history data stores “last” and” before last” occurrences of the particular data being viewed. The “last” data indicates the last key on cycle in which the data occurred. The “before last” data indicates the previous occurrence and its related key cycle. The data also references how many occurrences of the abnormality occurred on the related key cycle.
As an example, if the customer who reported shifting problems with the aforementioned Prius had last experienced the problem a week ago and travels to and from work with the vehicle, you could assume that a week’s worth of driving would be around 14 key cycles ago. If the technician retrieves data from this occurrence they will theoretically be able to match the data to the customer’s experience. Once confirmed, the advisor can communicate to the customer that there was an erroneous operation of the shifter and not a problem with the vehicle.
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| VCH Data is available on Toyota and Lexus vehicles through the Utility selection menu. |
This is a huge time savings in diagnosing Hybrid vehicle customer complaints.
P1604 – Startability malfunction
A few years back I noticed a P1604 DTC on my 2013 4Runner. There was no MIL illuminated on the dash and I was not having any issues with the vehicle. I happened to be researching material for an upcoming class and noticed the code while performing a health check. Upon further research I discovered that a P1604 indicates a “Startability malfunction.” According to Toyota Technical information: “This DTC is stored when the engine does not start even though the STA signal is input, when the engine takes a long time to start, and when the engine speed is low or the engine stalls just after the engine starts.”
After reading this I realized my startability malfunction came as a result of my removing my foot from the vehicle brake during engine cranking which resulted in a no-start.
So why does Toyota provide a code single for a wide variety of circumstances? Well, it comes down to data. Imagine you are Toyota’s technical hotline and every day technicians of all different levels of experience are calling for assistance with difficult diagnostic scenarios, many of which have no related DTC. The beauty of the P1604 was that it created a DTC and with that DTC comes valuable freeze frame information. Data makes life easier for all parties involved in the diagnostic process. The P1604 by design is a fantastic tool for those in the independent repair market when diagnosing no-code difficult starting concerns. As a note: be sure to diagnose other DTC’s first as many times a P1604 will set as a companion code as a result of another problem. For example: If there is a code present for a MAF sensor related problem along with a 1604, diagnose the MAF code first.
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| A Query of the VCH Utility menu reveals a list of triggered events with related time and key cycle information. |
Engine-related VCH data
Vehicle Control History Data is becoming available on Toyota vehicles and is available across multiple ECU’s. This vehicle control history information is a function that captures and stores data based on a specific vehicle behavior. The VCH data is incredibly useful and is quite similar to the concept of the P1604, however, VCH data may be available to the technician without storing a diagnostic trouble code.
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| Selecting a specific VCH event reveals related data. |
As an example, the 2018 MY Camry was a complete redesign of the Camry platform. With the redesign came VCH data for the Engine Control Module. The VCH data is available through the Techstream Utility menu after performing a health check of the vehicle. The VCH data is a revolution in diagnostic information.
One of the issues with a P1604 DTC was that there were multiple reasons, or what we refer to as code-set criteria, that resulted in a code. The problem with having multiple symptoms that could result in a single DTC is that time is of the essence- We simply don’t have time as technicians to properly diagnose in most cases. VCH data further narrows our diagnostic efforts by providing a subset of data, codes and freeze frame information that are not linked to diagnostic trouble codes. Think of this as data for no-code diagnostics.
As an example, The P1604 code has been further broken down within the VCH utility. Instead of simply setting a startability malfunction DTC, VCH provides sub-codes that can indicate in a more specific manner why the vehicle didn’t start:
- X0800 – Engine Stall
- X0803 – Engine Stall – Compression leakage
- X0810 – Engine Difficult to Start – Starting Time long
- X0811- Engine Difficult to Start – Engine Stall Immediately after starting
- X0812 – Engine Difficult to Start – Immobilizer
In addition to the “X codes” VCH data will also include enhanced freeze frame data related to the triggered event and will often include the ability to graph data over a period of time before and after the triggered event.
While it seems as though this information has been provided to ease the diagnostic complexities within the franchise dealership model, the wealth of information it provides will certainly provide independent technicians a wealth of information when diagnosing Toyota and Lexus vehicles in their facilities.
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| A VCH event triggered by ABS activation reveals the related data at the time before during and after the event. |
VCH for Toyota Safety Sense
In last month’s Motor Age, Toyota Safety Sense was covered in detail. The TSS system utilized multiple inputs as well as control unit algorithms that enable the vehicle to assist the driver. The complexity of these systems cannot be understated. As a result of the ability to access VCH data for these systems, Toyota has been able to analyze and publish their findings as they relate to autonomous braking.
As an example, an SAE white paper entitled: The Accuracy of Vehicle Control History Data During Autonomous Emergency Braking was published in April of 2018. This paper points out the level of detail available through VCH data. If you are interested in a deep dive into VCH data analysis, it is worth the price of purchase and is available at a discount to SAE members.
Locating VCH data
As mentioned, there are multiple ECU’s that store VCH data. In the Hybrid Control ECU, the HV Operation history is located in the data list.
For Engine, Body/SRS Airbag related VCH data, the utility menu for the respective module will be utilized.
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| The data stream within the saved VCH event allows the technician to overlay graphed data. |
Please note that the amount of available data for VCH will be dependent on what Toyota refers to as a data group. Each triggered event has a related data group and in turn, each data group has a number of data parameters that it will record.
To be sure on what data should be available, consult the Toyota service information related to vehicle control history.
The wealth of information available from VCH data to technicians in the independent repair market makes another strong case for Techstream factory tooling when diagnosing Toyota and Lexus vehicles. This information at the time of testing was not available through aftermarket scan tool platforms. As has been pointed out in previous MA articles, Techstream tooling and subscriptions are amongst the least expensive in the business with interfaces starting around $500 and subscriptions available in 2-day or yearly formats at $65 and $1295 respectively.
Data is essential in performing a competent diagnosis. Toyota VCH provides a level of data that has not been accessible to the technician in the past.
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The 411 on a P0420
My friend, who happens to be a fellow amateur radio operator, sends me a text message with a picture of a scan that has been performed on his 2012 Ford Fusion and asked, "Do you have a few minutes to help me find out the problem with my car?" He goes on to say, "Check engine light is on for a P0420. I'm sure it's just O2 sensors."
I'm usually cautious about volunteering information over the phone about what could be wrong about a vehicle when I haven't had my eyes, ears, or at least some scan data from the vehicle. I get even more cautious when my ham buddies, who are a lot smarter than I, ask me for input.
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| The subject vehicle is a 2012 Ford Fusion with 87,000 miles and an automatic transmission. The MIL is on, it's running rough and has poor performance. |
I don't have the confidence that I should when it comes to automotive diagnostics. I've been wrong more times than I can count and I don't want to be stuck with a nightmare I can't fix — especially when it's on a friend's car and when it's a "routine" P0420. When I look at catalyst efficiency codes nine out of ten times the ECM identifies a faulty catalyst. The ECM may hint at the reason why it failed with other DTCs but most of the time. We're left to find the reason why the cat failed on our own.
Sometimes we get unlucky enough that the replacement converter doesn’t fix the catalyst code. That is going to be a bad day for everyone involved.
OK, let's go for it!
There are five basic quick checks that I want to perform when I see a P0420. Those quick checks include identifying any current misfires or misfire history, identifying any fuel trim problems, validating the downstream oxygen sensor voltage, confirming that the downstream oxygen sensor is switching and searching my service information for software updates and/or common problems.
So I ask my friend, “Do you think this car has been misfiring before the MIL came on?" He believed his vehicle didn't start running bad until after the MIL came on and it's not always performing badly. It's an intermittent performance issue. That's backward from every other situation I've ever seen. Usually, it's running bad and then the MIL comes on with a catalyst efficiency code.
An auto scan of the vehicle confirmed that the only codes present in the ECM are a P0420 catalyst code and a p1000. For those of you who haven't seen a p1000 on a Ford product, it means the ECM has not completed all of its monitors. This is a really good hint that someone has been clearing codes before you worked on it. If he cleared the codes, he also erased any potential misfire history and Freeze Frame data that may have been stored. So at this point, I have to trust that if I cannot duplicate a misfire on my test drive or in the bay it didn't have a misfire. At this point in time, if the cat does prove to be faulty, I don't think a misfire is the underlying cause.
The next of my quick checks is to identify any fuel trim problems. Fuel trims problems are a bit subjective. What I mean by that is some technicians or instructors say that plus or minus 10 percent is ok, others say plus or minus 5 percent. When I have analyzed newer cars without problems, they are closer to plus or minus 5 percent in my experience.
I checked fuel trims and trims are darn near perfect plus or minus 5 percent even under load. It's important to check fuel trims during a road test in all operating ranges in order to rule out a trim problem. Like the misfire monitor, the fuel monitor is continuous and fuel trims can be off in one rpm/load range and just fine in others. I don't think a trim problem ruined the catalyst.
So I move on to my next batch of data. I start the car to warm up the cats at 2500 rpm for a few minutes and I watch the downstream 02s. The bank 1 downstream 02 is switching very rapidly, indicating the catalyst can no longer store oxygen. At this point, I agree that the cat is faulty but what caused it? I still haven't identified the performance problem either. I do know that my downstream oxygen sensor is not skewed low by an exhaust leak because it is switching from 0.1v to 0.8v. In my experience, a cat code set by an exhaust leak post cat will suck air into the exhaust and pull the downstream 02 low due to a high amount of oxygen in the exhaust.
After the MIL has been addressed I start to focus on the drivability problem. There were two big hints that led me to the path I chose next.
When I went for a drive I did a couple of WOT runs and I felt like the car had power but it just wasn't all there. The only reason I picked up on this is that my fiancé happens to have the same car which I drive frequently. This lack of power wasn't much but it was noticeable.
The second giveaway is the lack of a 1-2 shift under heavy throttle. I'm not saying I put the engine's safety in jeopardy but trust me it wouldn't upshift. I thought to myself at the time, this is going to be an expensive bill if he's got a transmission problem and bad cats. And then it hit me. I need to do a Volumetric Efficiency calculation.
Is this a breathing issue?
A VE test is used to identify breathing restrictions, or more precisely, it helps identify any issues with the engine's ability to take air in and get it out again. A volumetric efficiency test compares the total theoretical air charge an engine of a given displacement should be able to take in to what it actually takes in, and expresses it as a percentage. After all, an engine is really just a big air pump.
I recommend running the numbers several times with scan data to accurately average the data. To perform a VE test, you're going to need a safe testing area near your shop where you can safely perform a WOT pass, starting from a slow roll in first gear and continuing right up to the 1-2 upshift. You'll also want your scan tool plugged in so you can record mass air flow in grams/second, intake air temperature and engine rpm. Graphing is better than recording the data numerically. It makes it easier to pick out the numbers you'll want for the next step.
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| Notice the rise in intake air temperature during this VE test run. Why is the air in the intake getting hotter when it should be getting colder? |
You then put these numbers into a VE calculator. Many are available online — just "Google" it. During the 1-2 shift, the engine will be at its peak breathing range. With the car I was working on, I had to manually upshift this car to avoid engine possible damage due to over revving. What I saw in the scan data was very exciting to me!
A rise in intake air temperature during acceleration! I had never seen this before…ever!
Sometime ago, probably in early 2017, John Thornton was doing a class and this topic was brought up. I'm blessed to have had the opportunity to attend his classes. The conversation I had with John about rising intake air temperature was a side note in his class. A side note! I'm telling you this blew my mind. One thing about John if you have ever had him as an instructor is he is so humble, so intelligent, so dedicated but also just so simple sometimes. When he spoke of this technique a couple of my classmates were just mind boggled. I've only been working on cars for about six years now but I've done hundreds of VE calculations. Not once did I ever think to look at intake air temperature closely.
"On a good car," (and I'm quoting this from a text John and I shared), "I expect intake air temperature to decrease as air mass increases." How many times have I seen this and paid no attention to it? Hundreds of times I've seen this during VE testing. I never thought about if intake air temperature increased with a rising air mass that it would mean something - or be a useful diagnostic strategy!
What does it mean??
Intake air temperature drops under acceleration because the engine is breathing in lots of cool air and it cools the intake air temperature sensor and the engine. So if intake air temperature increases, we have a restriction preventing the engine from bringing in cool air. This restriction could be an intake restriction or an exhaust restriction. I suspected an exhaust path restriction due to the ECM setting a P0420 and the scan data evaluation.
Always prove the fault
I prove this another way. I've written before about testing your hypothesis two ways to fact check yourself. I’m already counting three different data points to condemn the cat. But I want to see if I can dissect this a little more. See the ECM didn't set a p0430, it only set a p0420. So I anticipated that the restriction was on the bank that set the cat code. I was wrong in that anticipation. The exhaust path restriction was notated on both banks, as you can see in my in-cylinder running captures with a pressure transducer. When I do a snap throttle test, both banks exceed 30psi on the exhaust stroke. So if my ECM is OK with my Bank 2 cat but there is a restriction noted on both banks, where is the problem?
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| Prove your fault with more than one test before pulling the trigger on a repair. In this case, I'm going to measure backpressure on both banks using an in-cylinder test. |
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| Both banks built up in excess of 30 psi on my snap throttle test. Exhaust restriction confirmed! |
In the rear catalytic converter. Like many V-6 and V-8 designs, there are three catalytic converters in the exhaust — one at each manifold and one downstream after the Y-pipe. The Bank 1 cat's ceramic, mounted to the rear manifold, broke apart and ended up clogging the rear converter almost completely.
The technique that John mentioned in his class really helped me with this diagnosis for one simple reason — understanding what a known good VE calculation for this engine? For a long time, an acceptable VE calculation range was 75 percent-90 percent.
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| The Bank 1 cat (the one with the P0420 code) had a failed ceramic that broke apart and clogged up the rear cat on its way down the exhaust path. |
What I want to focus on here is when I ran the numbers and averaged my VE calculations I was coming up with about 75 percent. Not too long ago this number was in an acceptable range and I may have blown it off and moved on, looking for another reason for the drivability complaint.
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| On the verification test drive, intake air temperature behaved more normally — cooling instead of heating up. | So this one caused the DTC and led to the cause of the drivability problem. |
The only way you would really know is by collecting known good data. The data for me happened to be sitting in my driveway when I got home. Sometimes we get lucky but at other times we are waiting for information. In this case, using the technique that I recently learned to help me get to pinpointing the problem much quicker because I didn't immediately have a known good. Next time you’re on a road test for a low power complaint grab your intake air temperature and absolute load PID and some downstream oxygen sensor data, and you should very quickly be able to identify a restriction in the exhaust!
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Ingersoll Rand releases new compact impact wrench series
The new Ingersoll Rand® W5133 IQV20 Series 3/8" Compact Impact Wrench is the next generation 3/8” impact that vehicle service technicians need to complete work quickly and without switching tools.
The impact wrench is more durable with stronger internal parts and has four forward power modes that always operate at max reverse torque. It is 7” long and has a tapered front end for greater access in tight spaces. It delivers 550 foot-pounds of nut-busting torque and 365 foot-pounds of max torque.
The following are features of the Ingersoll Rand W5133 Compact Impact Wrench:
- A variable-speed switch and electronic brake increase control while using the tool
- The brushless motor and impact mechanism are finely tuned to unleash an excellent power-to-weight ratio
- It provides technicians better ergonomics and accessibility while working in tight spaces with the angled handle
- The Chip-on-Board LED task light has four dimmable settings. The 360-degree ring of light eliminates shadows in the area that needs servicing
Vehicle service repair and industrial maintenance technicians rely on the W5133 impact wrench for power and durability in tough environments. The tool is available with a 3/8" or 1/2" square drive and weighs 5.3 pounds. The all-metal drivetrain and hammer mechanism delivers the power technicians need without adding extra weight to the tool.
The Ingersoll Rand W5133 has four forward power modes that always operate at max reverse torque, so operators don’t need to switch tools for different tasks. The four modes for forward control include:
- Max Power: Tightening bolts on brake calipers, transmissions, axles and flanges previously required a pneumatic impact tool. The max power setting delivers up to 340 foot-pounds of torque, so technicians do not have to switch tools when tightening bolts.
- Mid Power: The mid-power setting tightens fasteners at up to 240 foot-pounds of torque for applications that don’t require maximum torque speeds.
- Wrench Tight: Instead of changing to a hand wrench, technicians can use the tool’s wrench tight setting to tighten fasteners at 10-to-24 foot-pounds of torque. In this setting, the tool automatically shuts off so that bolts are not over-torqued on parts such as suspension bolts, motor mounts, brake calipers, bumper covers and lug nuts.
- Hand Tight: The hand tight setting turns slowly, creating a snug fit for parts such as valve covers, transmission pans, drum housings and other light fastening applications at two to nine foot-pounds of torque. When the tool reaches the point of impact, it also shuts off to avoid over-torqued fasteners.
The Ingersoll Rand W5133 withstands repeated drops and exposure to harsh fluids. The chemical-resistant composite housing and patented steel-reinforced frame increase durability. The spark-free brushless technology and reinforced bushing increase the lifespan of the motor.
The 20-volt battery is compatible with the Ingersoll Rand IQV20 Series battery system. To learn more about the Ingersoll Rand W5133 3/8" Compact Impact Wrench, visit www.IRTools.com/W5133.
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Need new tools? This is a way to add them for free
From battery testers to diagnostic tools, there are a number of new options technicians can choose from at TOPDON USA.
And for a short time, the BT Master Battery Tester could be yours for free.
TOPDON is encouraging technicians to like the TOPDON USA Facebook page and one technician will receive a BT Master Battery Tester.
Working with techs and for techs is just one approach TOPDON is sharing with repair shops nationwide. In fact, as a new option for diagnostic tools, there is the ArtiPad.
When you like the Facebook page, you’ll learn more about the scan tool featuring:
• Dealer-level functionality
• Advanced ECU coding and programming
• Interactive data logging sessions
• OEM repair information powered by Quick-Fix
• Much more
TOPDON reports that it is putting three key features into techs’ hands with the ArtiPad, starting with access to Quick-Fix Repair Information. Having access to the repair info can increase the power of the tool by making technicians smarter and able to work more efficiently. That is in addition to other time and money savings and top-level service from Cutting Edge Automotive Solutions.
Technicians and owner cans find out more by seeing the lineup of seven diagnostic tools by liking the TOPDON Facebook page. Click here to like the page and you instantly will be entered to win a BT Master Bluetooth Battery Tester!
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ZF Aftermarket’s latest product campaign is about you
Until Nov. 2, 2019, automotive industry professionals are being called to show their pride in the parts they choose to purchase and use, by submitting pictures with the hashtag 'ItsAboutThePart'.
Qualifying pictures are entered in a weekly and monthly raffle, where entrants have the chance to win a ZF branded Yeti tumbler or a ZF branded Yeti cooler, respectively, both filled with ZF branded swag. Pictures will also be blasted on social media channels to give auto shops recognition for its partnership with ZF Aftermarket.
The Double Meaning of #ItsAboutThePart
The campaign built around the hashtag has two key meanings. The first meaning is about the physical part. The part in the box is crucial to the success of ZF Aftermarket - meaning that parts are made with quality, care, and a dedication to perfection. ZF Aftermarket brings you an unparalleled range of OE quality products that meet or exceed OE specifications ensuring the job is done right the first time.
The second meaning is about the personal part. ZF Aftermarket isn't who they are without the part YOU play.
The auto care professionals who choose OE products focused on quality and safety make ZF Aftermarket possible. From purchase to installation to customer relationships, this choice helps keep the brand’s standards high from start to finish.
Show your pride in the branded parts you choose and submit your pictures now through Facebook, Instagram, or www.itsaboutthepart.com. Don’t forget to use the hashtag #ItsAboutThePart.
To learn more about the #ItsAboutThePart campaign, please visit www.itsaboutthepart.com.
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New method of parasitic draw testing leads to diagnosis of battery-killing Honda
While employed as a sales representative for a diagnostic tool manufacturer, I remember coming across a particular gentleman to whom I was trying to express how important it was for us to keep changing along with the vehicle technology confronting us. If I recall, he went by the nickname “Cooter” (hi Sam!). In a way that I thought he would comprehend, I strived to express how doing things the old-fashioned way on modern vehicles simply doesn't work. I mentioned computer-controlled alternators and then he interrupted me.
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Vehicle Information: 2015 Honda Civic Si |
He took offense to what (I believed at the time) was an educational opportunity, and let me know with a reply of "Are you calling me stupid? You think I AM stupid, don’t you? I've been doing it this way all my life! I don't need to be spending my hard-earned money on your high-priced equipment!”
Of course after that there was no point in continuing to convince him that sometimes employing the old fashioned ways may not be a wise choice and they may actually cause more problems than they solve. There was simply nothing I could say to “Cooter” that would help him understand he could improve the way he was diagnosing vehicles or to get him to consider other ways that would accurately and efficiently diagnose today’s vehicles.
As I was leaving his shop, I remember him trying to tell me that “no equipment could tell (him) the alternator was faulty any better than” the method he uses. He said if he “disconnected the battery cable while the engine was running then he’d know one way or the other.” Yes, I cringed when I heard that. Hopefully, you did too when reading it.
What would you do if someone told you there's an easier, more efficient way to do something that you have done the same way for a long time with excellent results? I’d say “prove it!” In most cases there's no reason to change the way we are doing things as long as they work and provide us accurate information. There are circumstances however, that make you have to change — maybe against your will!
It really doesn't matter what brand of vehicle you are working on when you are trying to address a "parasitic drain" (also called a “parasitic draw” or just a “draw”). The problem is usually that the vehicle’s battery has gone dead with no reason, within an unreasonable amount of time.
This may be that day!
In the “old days,” to diagnose a parasitic draw — on a vehicle with the key off — we would disconnect a battery cable and put a non-powered test light in “series” or in other words, between the cable end and the battery terminal. If the light lit, we knew we had a draw. If the light didn't, either the problem was intermittently occurring or we knew that something was probably left on and has now been turned off. Once sure there was a draw, we would disconnect one fuse at a time until the test light didn’t shine anymore. A long time ago the fuse blocks were fairly simple and usually identified the whole circuit each fuse protected so we knew which system was affected and would start working towards the component at fault – isolating items that fuse fed.
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| Sometimes there are more tools than engine in the engine compartment! |
After electrical systems became more complex it became imperative we had to have accurate service information that included electrical wiring diagrams. With the advent of “Maxi” fuses providing many smaller fuses with protection then came the time when multiple circuits could be protected by one larger-capacity fuse. We would begin the tests the same way (test light attached at the battery), but then we’d disconnect the high amperage rated fuses one at a time. Once we identified which of the higher amperage fuses were carrying the parasitic load (draw) then we’d pull those lower amperage fuses that were protected by it one at a time.
Some of the more nerdy among us folks would install an ammeter in series instead of a test light. I found knowing how many amps draw I had helped me eliminate some circuits that could have been suspect. For example, a draw higher than one amp could not be caused by a glove box light staying on. However, do you know what problem I found when employing an ammeter into a circuit with an unknown amount of amperage flow? Yes, sometimes my meter’s fuse would blow and those weren’t cheap! Alas, I learned to use an inductive ammeter I repurposed from a farm tractor, attaching it to one of the battery cables prior to disconnecting it, and then I had a good idea how many amps I was probably dealing with before attaching my ammeter. I blew far fewer meter fuses when I did that!
Drain caused by computers?
In addition to the higher number of circuits being added to the vehicles were also computers. The “standard procedure” we were following to diagnose parasitic drains at that time was found to sometimes result in us having to write on the work orders “NPF” (which stood for “No Problem Found”). Unfortunately, very soon thereafter we had to recheck the same vehicles again and again. What was happening was a module or component was causing a draw until the battery was disconnected! They would “reset” and work as designed for a while. As soon as we placed our test lights in series, the problem was gone. Sometimes we were fortunate enough that the problem causing the draw could be recreated while the test light was still connected, most times we couldn’t.
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| Every now and then the DVOM would momentarily display a higher current draw than usual. Such a reading helped me decide to use a scope instead of a DVOM for this diagnosis. |
This phenomenon was the reason we had to change our method. From that time until today, anyone that's got to address a vehicle that has a parasitic drain would typically grab a DVOM (Digital Volt and Ohm Meter) and an inductive Low Current Probe (LCP). The probe is used so that a battery cable doesn’t have to be disconnected and fuses do not need to be removed to find an affected circuit. If an excessive current draw is detected at a battery cable on a modern vehicle the combination of DVOM and LCP greatly reduces the potential for a circuit to be disturbed, thereby ensuring if the draw is caused by a module, it will continue to do so until we isolate it. We can use the LCP on circuits protected by any size fuse and work our way from the battery to the component just like we did in the “old days” using a test light.
The Halloween Honda story
I was recently called into a mechanical repair shop because a vehicle's battery was unintentionally discharging so quickly that the vehicle would not restart if it sat overnight without a charger. The vehicle owner did not correlate this problem to the collision shop repair because that had been done several months prior without any problems occurring like this since.
As if it were timed for Halloween, this 2015 Honda Civic with a Rice Burner 2.0L L4 DOHC engine and manual five-speed transmission had been repainted the “perfect” color. Several months prior to seeing the vehicle for my first time this vehicle had been in a collision resulting in extensive body work. At first I was unaware why it had been repainted that color, thinking to myself it may have been a combination of things — that the owner must be color blind and the body shop doing the job wanted to get rid of a bad purchase (lol). Turns out that “Pumpkin Orange” was the color the owner actually wanted! Well, as the saying goes, to each his own.
Anyway, I begin all of my parasitic draw diagnostic routines by checking the state of health of the vehicle's battery first. I have been burned in the past by testing systems that were acting unusual only to find their voltage was right at the border of being acceptable. Modules have a way of acting unusual without proper voltage or ground.
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| Figure 1 |
Having confirmed the battery state of health (Figure 1) was at 80 percent, I deemed it acceptable for further testing so long as a battery charger was attached. I proceeded to connect my DVOM and LCP to check for the draw. Seeing a 200 milliamp draw made me start considering things like a small light and other small draws. I stared at my DVOM display long enough to see a momentary display of close to 500 milliamps. It was that momentarily higher display that caused me to use the min-max function to see whether or not there was something surging in the circuit. And, yes there was.
I thought it best for me to use the Pico scope to graphically depict the amperage in order to help me analyze this parasitic draw. I'm very thankful that I did. The image captured (Figure 2) looked almost like an injector voltage waveform!
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| Figure 2 |
The image displayed made me somewhat confused at first. Realizing I was up against some sort of a controlled circuit, I decided to sit inside the vehicle and just observe. I was expecting something to turn on or give me a sign. Initially, none of the courtesy or dome lights were turning on, none of the gauges were flickering and the instrumentation was not displaying anything unusual as.
The thought occurred to me to cover the windshield to stop the outside light from coming in. That was the key in diagnosing this vehicle's problem. I was able to see flashes of dim light displayed on the driver information center/navigation system! It was then I decided to head for the radio fuse and put my low current probe on that circuit. That was exactly the same image as what was displayed at the battery. I’d found the culprit. Now what?
I found in the Service Information a procedure for a “Self-Test” that could be run on the Infotainment system. Surprisingly, every part of all the very extensive tests passed!
I felt it was time for a visual inspection of the unit and removed it from the vehicle. On the bench it was evident – water damage! Once the problem was identified, the customer acknowledged the windshield had been broken in the crash several months ago, and the vehicle was left exposed to the elements for many days with that condition present. We concluded the navigation audio/infotainment system had been subjected to water damage after the windshield had been broken during the collision but wasn’t showing signs of damage until rust had set in and affected certain circuits internally. A replacement unit resolved the parasitic draw. After the navigation audio/infotainment system had been replaced with a used unit, the Security light is the only draw (Figure 3).
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| Figure 3 |
So, in this case, as happened to me several decades earlier, I learned of a new way to help me diagnose a parasitic draw. Using a DVOM I was only supplied a digital representation of the fault, which proved to be woefully inadequate. Using a scope instead of a DVOM, I graphically displayed the circuit condition, which completely changed the direction in which my diagnosis was headed.
Again, I cannot stress enough the importance of having accurate service information when attempting to diagnose this condition (parasitic draw). A wiring diagram and sometimes a wire routing diagram as well as component location information, can make diagnosing a parasitic draw much easier!
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Is there a writer in you?
You may have heard me say before how thankful I am to be able to do what I do. After spending most of my working life turning a wrench, the opportunity to now help those still in the bays is something I never take for granted. Along the way, I've met hundreds, if not thousands of techs, shop owners and educators from every corner of the globe.
I like to think I'm on a first-name basis with all of you.
And I also like to think that the relationship I have with our readers is one thing that makes Motor Age unique among automotive trade magazines. No matter where I go, what event I attend or presentation I make, there are always a number of you that take the time to say "Hello" and share your stories with me. In addition to hearing from you in person, I also receive your emails, social media messages and YouTube comments. I am humbled whenever a reader shares that something he (or she) saw in the magazine, our YouTube channel or in one of our webinars has provided a means to perform a job easier, tackle a diagnosis more productively and, in the bigger picture, make a better living for themselves and their families.
So how did you get started?
A common question I'm asked is how I got started writing for Motor Age and many of you have followed up by asking how you could follow a similar path. Let me start off this month's column by addressing the first question.
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| My job with the magazine allows me to travel quite a bit and take part in projects I otherwise would never have the opportunity to participate in — like this A/C training I hosted for the servicemen at MacDill AFB in Tampa. |
It all started with a Lexus EVAP fault that was kicking my backside while still working in a shop for a living. Even then, I believed in continuing my education and attended training classes in my local area as the time and opportunity allowed. I also kept up with the industry online by participating in the International Automotive Technicians Network (iATN) and reading the trades.
For some reason, I just couldn't make any sense out of the system operation description the shop's service information system had on the Lexus. Using the resources I had, I put together a tool box reference that outlined the operation of the four different EVAP systems Toyota/Lexus were using through that time. I also made notes about known issues and their fixes, all with the idea of throwing it in my toolbox.
My wife, God bless her, had other ideas. She suggested I take what I'd spent all that time at the dining room table assembling and submit it to "one of those magazines you're always reading". So I did!
That first article was published but not by Motor Age. As I've since learned, the content you're reading today was planned nearly a year prior and there were no open slots for an EVAP article. However, both the managing editor and technical editor of the time thought enough of my writing style to ask me to write for MA, starting with case studies and lessons learned that would be shared in the "Garage" column.
The rest, as they say, is history. As time with the magazine grew and opportunities became available, I began to do more and more on a freelance basis. And from there, the chance came to join the group fulltime and here I am.
But, as I share every chance I get, I always try to stay grounded and remember where I came from. I go to work every day with the primary goal of finding new ways that I, and the magazine, can help you succeed and grow in this ever-challenging profession.
Can I write for Motor Age?
I am thankful and proud of the contributors that grace the pages of this magazine every month. Every one of them is an accomplished technician and most are nationally recognized trainers. Even so, I am always on the lookout for the "next generation" — those that will grow to lead this industry long after I, and others, have closed our toolboxes for the last time. And I've found a few. Talented technicians like Brandon Steckler, Mike Miller, and Mike Reynolds — just to name a few.
Some that still write for me and some have moved on to bigger and better things. And some that have yet to be introduced in these pages. But not to worry — you'll get to meet them in 2020!
Are you one of those next generation leaders?
Writing for a national trade publication requires more than being a competent technician. You also have to be a competent researcher, decent writer and storyteller.
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| Even though I don't wrench fulltime anymore, I still try to "stay dirty" so I can keep up with all of you! |
Most importantly, your desire to write for us should be based on helping others. Writing and teaching others because you want them to succeed is a trait shared by every contributor on our team and it is obvious when you see and talk to them in person. Writing just to see your name in print will be obvious in the content you submit.
Be warned! Mentally prepare yourself to have your articles dissected by nearly half a million technicians who will read that article in these pages or online. Make a mistake in your theory or process and you can be assured you'll be hearing about it in your email!
I don't look for perfect writers. I do expect submissions to the magazine, though, to at least be spellchecked and formatted somewhat properly before I get it, just to cut down the workload on my end!
I start every new writer out with "Garage." This monthly feature is a cornerstone of our magazine and a feature I used to look forward to every month. It's more than just a case study - it's a story of a challenge faced and overcome, and the lessons learned in the process. One of my personal favorites is a challenge faced and nearly lost, but the lessons learned in the process were invaluable.
We all have those kinds of stories. The ones we share with our fellow techs over a cold beer at the end of the day. The ones that start with "that (fill in the OEM of your choice here) nearly kicked my a--!" I'm betting you have one or two of your own, don't you?
If you'd like to submit a story idea, here's a few tips for you.
1. The submission, for our print issue, has to be between 2,000 and 2,500 words. The Word program tracks this for you in the lower left of the open document window.
2. Avoid reusing common phrases. Reading "as well" at the end of every other sentence is a bit tiring to the reader and especially tiresome to the editor!
3. Write it like you'd speak it. Don't try to be too formal — be yourself!
4. Illustrations have to be more than screenshots and MUST be high resolution. This is one that trips up even experienced contributors. Low resolution images work fine online but will not reproduce well in print. Illustrations should be 300 DPI OR a larger image size (like cranking up your phone or camera to record the highest file size image it is capable of). Each story requires 6 to 8 illustrations that are independent of the story and the more, the better.
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| See! I did work as a fulltime tech once upon a time! |
Oh, and if you include a photo or image that you, yourself, did not create be sure you have permission to use it!
If you do decide to send me a submission, send it to pete.meier@ubm.com. Be prepared for it to take a bit of time for me to read it over and send you my critique. And don't take offense if your first few tries don't make the cut. I'm betting your first few oil changes or brake jobs weren't perfect either.
Who knows? You may be invited to contribute regularly to America's oldest trade publication — Motor Age!
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Repeat ignition coil failures: A lesson in troubleshooting
Every now and then an interesting diagnostic problem comes into the shop. Many of these problem vehicles come from other shops and many of the vehicles have been backed up to the parts store and loaded up with everything in sight. This 2001 VW Cabrio was one of those vehicles.
You might think a car this old would be a car that nobody would invest any money in, but please keep in mind, beauty is in the eye of the beholder and when a person loves their car, takes great care of it and keeps up on the maintenance, the vehicle will last a long time. While I had this car apart, the lady owner walked into the shop and loudly exclaimed, “MY BABY.” I think she had a love affair with this car.
"Baby" has a problem
The story of the problem started out about 6 months earlier. The lady owner was on her way home from work on Friday evening. Her commute was 134 miles. She was 50 miles from home when the engine lost power and died. The car was loaded on a flatbed and hauled to a shop that specialized in VW, Mercedes Benz and Volvo vehicles. The shop found the problem was caused by a bad ignition coil, so a new coil was installed. The engine started and ran OK and was driven about two weeks before the engine stalled again.
The vehicle was hauled back to the European shop, only to find the shop had closed its doors so the vehicle was hauled to another shop for the needed repairs. At shop #2, they replaced the ignition coil, put in a used ECM, installed a new distributor and put on a new MAF. The vehicle was driven for two weeks and stalled again. The car was taken back to the shop where they found the ignition coil had failed yet again. A new OE coil from the dealer was installed. This repair also lasted about 2 weeks, then the stalling problem reoccurred. At this point, the car was brought to my shop to be fixed.
Each time the engine stalled, the problem has been the ignition coil quit making spark, and installing a new ignition coil got the engine running again. Any time I hear something like this, my mind always wonders if the problem is really an ignition coil or is the defective ignition coil a product of something else that is causing the ignition coil to fail.
Let's take a look
With the Cabrio at my shop, I found the engine could be started and it would run about 15 minutes and then stall. The engine could be restarted and it would run, and then stall again. Each time the running time would get shorter until it would not run at all.
On any problem like this, my first step is to always take a look at anything stored in the computer’s memory. A scan tool was hooked up and all modules scanned for any clues that might have been stored in memory. There are a few codes stored in the ABS module and two codes stored in the PCM. Code P0341 (Camshaft Position Sensor circuit range/performance) and P0102 (MAF flow too low). The P0341 code is set by the CMP and the CKP signal correlation being wrong. My gut feeling is the P0102 code is set by the engine not breathing properly. Clearing the codes, starting the engine and running a few seconds until it will stall will cause both codes to come back. At times, the codes must be cleared before the engine will restart. This engine will run with the CMP sensor unplugged so the P0341 code is not an issue with the stalling problem.
My first question was, “What is going away, spark or fuel? To answer this question, I used two current probes and my lab scope. One current probe went to the ignition coil power feed while the second went to the #4 fuel injector power feed. I also hooked a voltage probe to the CKP and CMP sensors. The engine was started and allowed to run until it stalled. At this point, I have my first test results to find a direction.
What has changed?
In Figure 1, the waveform shows a problem with the ignition coil current. Something has caused the coil on time to suddenly increase to the point that would overheat an ignition coil. My next question is, “What is causing this problem? Is it the ignition coil itself, is it an input to the PCM or is it the PCM that is causing the destruction of the ignition coils?"
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| Figure 1 - Scope capture of the CMP voltage, ignition coil current & fuel injector current. I found the reason for the engine stall when the ignition coil control was lost. |
The ignition system on this engine is a distributor ignition system with the CMP (Camshaft Position Sensor) housed inside of the distributor. The ignition is triggered from a CKP (Crankshaft Position Sensor) that reads from the reluctor on the crankshaft. The CMP has no effect on the ignition system and is used only to identify cylinder 1 position. Let’s take a look at a wiring diagram to see how this circuit is designed.
The wiring diagram in Figure 2 shows the single ignition with a built in driver housed in the ignition coil. There are only three wires to the ignition coil; power, ground and the trigger from the PCM. The haunting question is what is causing this car to destroy its ignition coils? So far in the repair history, it has had three different coils installed. The first two were an aftermarket part and the last coil was purchased from a VW dealer. All coils failed in the same manner.
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| Figure 2 - Wiring diagram showing the design of the ignition coil & its control circuit. |
Any time I am confronted with a problem like this, I will ask myself what has changed? After all, this vehicle is over 10 years old. I can understand it having one ignition coil failure, but not three. What has changed to cause this problem?
When it comes to an ignition coil failure there are only three things that come to my mind; 1.) something is causing the ignition coil to work too hard; 2.) something is causing the ignition coil to be turned on too long resulting in overheating; or 3.) the ignition coil has worn out from a long life. Since there have been multiple coil failures, we can rule out No. 3.
Nailing down the cause
Since I have verified the stalling problem is ignition related and is caused by the ignition coil failing when it gets hot, the next step is to find out why. We have two diagnostic trouble codes that might help give us a direction. Over my years in this business, I have seen a low flow MAF DTC stored by an engine breathing problem, so that is where I want to start my quest for information.
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| Figure 3 - Photo of the TDC mark on the flywheel & the distributor not in the correct position. |
Since this engine has had some work done to it, I want to verify a few things. I have a cam timing code so I want to address this first but I feel that I might be able to fix both the low MAF flow code and the CKP/CMP code at the same time. This engine has timing marks on both the crankshaft harmonic balancer and the flywheel. The flywheel inspection plug is already missing so it is easy to turn the engine and line up this mark. In Figure 3 you can see the mark on the flywheel is in the correct position. I have taken the hold down clamp off the distributor and the aligning pins are not in the correct position.
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| Figure 4 - The camshaft is 1-1/2 teeth out of time. Strangely, the engine ran smooth, although it was lacking in power. I have no idea how long it had been driven in this condition. |
Since the timing belt cover is already loose, let’s have a look at the marks on the camshaft sprocket. With the crankshaft mark at TDC I found the mark on the cam sprocket is 1-1/2 teeth advanced (Figure 4). Removing the clamp from the distributor, I found the distributor had been installed in the wrong position, possibly in an attempt to eliminate the P0341 code. I feel that the cam is out of time (which lowers the volumetric efficiency of the engine) and this might be the cause of the MAF code.
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| Figure 5 - Crankshaft timing belt sprocket with the locating lug broken. According to the vehicle owner, the timing belt had never been changed and this part had never been taken off the engine. |
At this point, the engine was in need of a timing belt so a new belt was installed. During the belt installation process, I removed the crankshaft sprocket. The bolt holding the sprocket on was very tight. After talking to the vehicle owner, I learned that the belt had never been changed but when I removed the sprocket I found the locating lug was broken in the gear. (Figure 5). Finding this explained why the timing belt was 1-1/2 teeth out of time.
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| Figure 6 - The scope capture shows the ignition coil current is following the coil control from the PCM. |
With the new timing belt installed and the distributor properly installed, the P0341 DTC is gone. The vehicle was test driven for a few miles; the engine runs good, although it seems to lack power especially at high RPM. With the vehicle at the shop, the engine was run at 1500 RPM for about half an hour when the engine stalled and this waveform was captured (Figure 6).
Better, but not fixed yet
The waveform shows the ignition coil current following the command from the PCM. I had to ask myself is the PCM supplying a pulsed signal to trigger the driver in the ignition coil or is the PCM pulling the 12V output from the coil driver low to trigger the coil? To answer this question, I unplugged the ignition coil and put a power and ground to the coil. I then had 12V on the signal wire from the ignition coil, so the PCM is in charge of pulling the circuit low to trigger the coil. My next question was what is causing the PCM to suddenly increase the on time of the coil, causing it to self-destruct?
In researching this coil driver, I found it is a “smart driver” and has the ability to report back to the PCM things like misfires and KV demand so the PCM can make adjustments to the control of the ignition coil. In this case, the ignition coil is overheating, and then the coil driver goes and loses its mind and turns the coil on way too long, resulting ultimately in the engine stall.
When it comes to an ignition coil being over worked, there are three things that come to mind: 1.) the resistance in the secondary is too high; 2.) the air fuel ratio is too lean; or 3.) the coil driver is leaving the coil on too long. I think I can rule out the problem of the coil driver, since there are no problems with the coil on time until the coil overheats. That leaves only fuel mixture and secondary ignition.
In going over some of my scope captures of the secondary ignition, I noticed the engine would idle with a KV spike from 9KV-15KV, depending on engine RPM. This is a little higher than normal although this in itself shouldn’t cause coil failure. The only thing left is air/fuel ratio. This makes me kick myself in the back side, since I did not take a look at the fuel trim at all. In fact, it totally slipped my mind.
Fuel trim provides the clue
Going back to the stored diagnostic trouble codes, the P0341 has been fixed with the new timing belt. I thought the P0102 DTC would also go away when I got the engine to breathe properly but now it’s time to address this problem. With my Ross-Tech scan tool hooked up, I noticed some data that didn’t look right. In Figure 7 data block 2, the last two fields, injection timing and mass air flow sensor data should both be very close to each other. This is something I have paid attention to on VW vehicles over the years, it’s just one of those quirky things I look at when working on VW MAF problems. The next thing is in data block 31, field 1 and 2. VW does a great job of giving many PIDs of actual and specified. Any time you see those two together, pay close attention. In this case, the actual and specified are not even close.
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| Figure 7 - Scan data of the MAF data and fuel trim data. This data plainly shows the MAF is not reporting the proper amount of air going into the engine. |
The last data block, 32 tells the final story. Field 1 is showing fuel correction at idle from the oxygen sensor. This fuel trim is not like generic long term and short term — it is the actual correction at idle in field 1 and the actual trim off idle in field 2. Trying to relate this to long term and short term in OBD2 generic will cause you to age very quickly. When this data was taken, the engine was at idle, and is reporting 10% correction on the scan tool. To compare that to OBD II generic trim, that would be close to a 20 percent correction.
Now, without having to get out of the driver’s seat, you can watch these three data blocks, run the engine at different speeds and get a very good idea how the MAF is reporting the air being inhaled by the engine. In this case, the MAF is out on vacation, The MAF on the vehicle is a brand new part. In this case the NEW means Never - Ever - Worked.
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| Figure 8 - Scan data with the new MAF installed. Now the data looks correct and then engine is running like it is supposed to run. |
A new MAF sensor was installed and the engine started and test driven. The data is Figure 8 tells the rest of the story. Data block 2, fields 3 and 4 are very close to each other. Data block 31, fields 1 and 2 are very close to each other and data block 32 fields 1 and2 are right where they are supposed to be. The problem of the coil failures is now fixed. Since these repairs were made, the vehicle has been back several times for service and has had no problems with the ignition coil.
Vehicles with problems like this, I call “sandwich vehicles” since there are so many problems all sandwiched one on top of each other and the only way you get to the bottom of the problem is by persistence and following a logical testing plan.
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A collection of shop experiences with European makes
Let’s start our trip across the pond with a BMW that is one of the most commonly sold Euro vehicles in our country. A 2012 BMW X5 came into our shop from a recommendation from another one of our customers. The lady that owners this BMW had taken the vehicle to the BMW dealer already and was not satisfied with the repair that was performed.
The problem on this X5 was that the vehicle’s battery would go dead in a couple of days. Now if you’re thinking that this dead battery was caused by something that they missed such as a parasitic draw, you're correct. Take a look at the dash display warning messages (Figures 1 and 2) that were displayed as a result of the problem.
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| Figure 1 |
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| Figure 2 |
The dealer had recommended that the battery and alternator be replaced in order to solve the problem and performed the repairs. Unfortunately, after the repairs were performed the vehicle still had the same problem it had prior. She brought the vehicle back to them a couple of times but they were, for some reason, unable to resolve her concern.
We started our diagnosis at the most important electrical power component in any vehicle, the battery. We found that the battery was low after performing a battery, starter and alternator test. The Midtronic battery test results stated the battery needed to be charged and retested. Our next move was to attach our Associated battery charger and set it to the AGM setting to charge the battery up to specifications. After the battery was fully charged, we repeated the battery test, but the battery failed once again. We charged the battery one more time before we condemned it.
But before we called the vehicle owner, we installed one of our new AGM batteries so we could continue our check of the starter and alternator. There is nothing worse than calling a customer multiple times and telling them each time you found something else wrong. My lead tech Bill had also performed a vehicle scan to check for codes and battery registration. Since there were no codes and the battery was properly registered, the problem had to be elsewhere. With a new battery installed, Bill proceeded to retest and continued to look for the problem. The issue he found was not with the alternator but rather a problem with the negative battery cable current sensor. Now we felt comfortable calling the customer and recommending that the battery and the battery cable current sensor both be replaced.
The BMW owner refused to provide the information for the battery warranty and told us just to replace the battery since she no longer wanted to deal with the BMW dealership. We followed her request and installed a new battery and negative current cable before starting to test for a parasitic draw.
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| Figure 3 |
Bill proceeded to test for the parasitic draw by installing the shop's (Figure 3) Fluke 233/A meter along with our Fluke i30s amp clamp. The amp clamp has a big enough jaw opening to fit around all battery cables that we have encountered so far. The Fluke i30s amp clamp is our tool of choice for parasitic draw since it can accurately measure current with a resolution of 1 mA / 5 mA up to 30 A. Since the amp clamp sensitivity range is 100 mV/A (100 millivolts equal 1 amp) our reading on the meter (Figure 4) is not interpreted by using the decimal point but rather by just reading the 3 digits. This is a very confusing problem for technicians when they use an amp clamp on a meter. I have seen this confusion for years both in seminars and hands on classes, so in both my electrical and scope books I make sure to highlight the use of an amp clamp on a meter.
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| Figure 4 |
On this vehicle Bill selected to use the millivolts scale on the meter since it’s the most accurate and can read up to 600 mV (6 amps). If the meter’s display reads OL, the limit has been exceeded. Then all that needs to be done is to move the meter dial to the voltage position and read the display. On our X5, the maximum milliamps reading is 40 mA, anything over that indicates a problem. The reading that our meter displayed on this X5 was 26.5 (Figure 5).
Remember what you just read above? The 26.5 is NOT 26.5 milliamps but rather 2 amps 650 milliamps - that is way over the 40 milliamp maximum tolerance! Can you see why the new battery that the BMW dealership installed was draining down and went bad? Our next step was to find out where the problem was coming from. We could have started our diagnosis by disconnecting the alternator since a shorted diode can cause a draw, or voltage drop each fuse, or last but not least disconnect one fuse at a time. All those methods have been used for years but take time to perform. We found a better method allowing us to be more proficient was by using our thermal imager on a cold vehicle.
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| Figure 5 |
We checked all around the vehicle until we found a bright color on the thermal imager screen. Take a look at the short video that we shot on the X5 to get a better idea on how helpful using a thermal imager can be. Go to our YouTube (tstseminars) channel by plugging this link into your browser of choice: https://www.youtube.com/watch?v=j5utqUC1xhw&t=4s.
Using the thermal imager, we were able to check the alternator and fuse boxes, followed up by looking all around the vehicle. We found the driver rear door handle was causing the thermal imager to glow a bright yellow (Figure 6), indicating a draw. If you’re not familiar with the Passive Entry door handles on a BMW, I will explain.
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| Figure 6 |
BMW uses special door handles on some of their high line trim models called the Comfort Access System or CAS for short. The first vehicles that used this system was the BMW 7 series. The system uses a Passive Entry that allows the driver to open up the trunk or door without using the vehicle transmitter/fob. Passive Go is another part of the system that allows the driver to start the engine without using the transmitter and Passive Exit, closes in some cases and locks the vehicle, without using the transmitter. The door handle has a sensor that sends a signal to the CAS, allowing the door to be unlocked when the handle is touched. The CAS has many other functions on this vehicle but the one we were concerned with is the door handle.
We proceeded to remove the door panel, followed by removing the wires from the load - the door handle actuator/sensor. With the wires disconnected from the door handle we rechecked the current draw on the meter. The draw was now under 40 milliamps, indicating that we found the source of the draw that caused the battery to go dead. We had to wait to use the thermal imager to check the door handle since the handle was still hot as the result of a shorted actuator/sensor in the handle.
When we returned to recheck the door handle the imager displayed no draw by matching a blueish color on the screen that was equal to the other 3 door handles. We called the vehicle owner to explain what we had found, unfortunately she decided to have us just leave the door handle disconnected since it would still function normally except for touch open and auto lock. We released the X5 to a happy customer that no longer had to deal with a dead battery or the stress of hoping the vehicle would start.
A BMW MIL
Next is a 2004 BMW 745i N62 that came in with a Check Engine light illuminated along with a few other issues. Even though this Bimmer had 172K miles on it, the vehicle owner still wanted to repair it. He had already tried Seafoam, a chemical carbon cleaner, and then taken his vehicle to an aftermarket BMW shop. The BMW shop tried to resolve the problem by using other professional carbon cleaners to clear the clogged Secondary Air passages in the cylinder heads. The results were not what the 745i owner wanted to hear or for that matter see, the codes came right back and illuminated the Check Engine Light. The shop recommended removing the cylinder heads to properly clean the passages and keep the MIL off. The Bimmer owner did not like what he was told and went for a second opinion. The second opinion was given by the BMW dealer who also recommended the same course of repair. Since we had worked on his BMW in the past, Robert decided to give us a call and see what we thought. After speaking and emailing us a few times he had decided to drive from Ohio and have us diagnosis and repair his 745i.
We did not want to let this customer down and knew that if we could not properly clean the air passages the Check Engine light would once again illuminate and we would look bad and have an unhappy customer. When the vehicle arrived, we connected our scan tool and performed a full vehicle scan that came up with the following DTCs 170 10080 (P0491) and 171 10081 (P0492) - Secondary Air Injection Insufficient Flow Bank 1 and Bank 2. This was the same information the other shop and BMW dealer had diagnosed. We had already done some research on this BMW Secondary Air problem and came up with a different solution that we found on the AGA tool website. Since we had used AGA tools on other BMW problems with great success, we thought that it was worth a try.
We explained the option to our customer, Robert, and asked him to review the AGA video. The video had a good explanation of the problem and the solution on cleaning the air ports on a 745i N62 motor. We explained to the owner that this was a less expensive way to clean the sixteen air injection ports without removing the cylinder head. Even though this is a time consuming job it is way easier and cheaper than removing the cylinder heads.
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| Figure 7 |
The first step of the procedure is to install the AGA BMW Secondary Air N62 tool and funnel (Figure 7) followed by pouring a carbon cleaner down into the secondary air tubes. The cleaner we chose to use, Run-Rite, was the same one that we have been using for years on carbon issues and has always yielded us good results. We started by removing the air tube on Bank 1 first (right/ passenger side) and proceeded to pour the cleaner down. We then followed this by performing the same process on Bank 2. We ran the engine and then let it sit a bit before restarting it then drove the vehicle. There was a load of smoke on our test drive that exited the exhaust system that meant it must have cleaned up some of the carbon. This is the first step of the AGA suggested cleaning process but may not be the last.
If this procedure does not break up all the carbon and the MIL illuminates for the same DTC, then phase two must be performed. As luck would have it, the procedure did not fully work even though the MIL stayed off for a few test drives. We informed the owner that we recommended a repeat of step 1 for the next course of action to see if the results were any better. Unfortunately, the results did not solve the problem so that meant step two of the cleaning process needed to be performed. Since Robert has been a very good customer over the years, we provided him with our shop loaner vehicle so he could drive back to Ohio.
We knew that we had our work cut out for us since our two upper secondary air port cleaning only made a small difference. The carbon was going to be extremely hard and difficult to remove. AGA makes two different cutting hooks that can be used to break the carbon from the passages. One of the hook tools is more rounded at the tip and the other is more squarish and looks more aggressive.
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| Figure 8 |
The next step was to secure the engine, remove the exhaust, drop the engine cradle and exhaust manifolds so we would have enough room and access to properly clean the air ports. As you can see from the picture (Figure 8) the air ports were clogged with carbon. This was a time consuming job that took hours of hand cleaning one port at a time. I started by selecting what I though was the worst looking port so I could gauge the time it would take to clean the other fifteen ports.
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| Figure 9 |
As I proceeded to clean the first port, I encountered heavy resistance so I decided to spray an intake cleaner as I was digging (Figure 9) and poking the tool into the port. After some time and much effort, I had success in cleaning the first port (Figure 10). Now I knew what I was in for cleaning the other ports. In the process of cleaning the other ports I wore out and broke a few of the hook ends. We called AGA and they overnighted a few more replacements just to make sure we would have enough to finish the job. While we had the vehicle apart, we noticed there was an oil leak from the rear main seal and others from the oil pan. We suggested to Robert that since we had access to the pan, we remove the transmission and replace the rear main oil seal and oil pan gasket. Our customer is a mechanical engineer who is super fussy and likes everything replaced. Robert had us order new oil pan bolts, new control arm cradle bushings and bolts, front transmission seal, transmission pan gasket and pan bolts and so on. It looked like Bill and I were going to replace everything from the starter to oil lines and just about everything else. As an engineer Robert understands the stress that each component has to go through with hot and cold, never mind the mileage that was on his 745i.
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| Figure 10 |
After waiting for three weeks or more, the bolts finally arrived from BMW and the time had come to reinstall everything we had taken apart. This vehicle was now in Bill’s bay for over a month, we thought that Robert was going to have us replace just about everything we touched. Now we had to make sure the Secondary Air Ports were flowing freely. We connected our Power Probe Hook since we needed amperage capability to run the Secondary Air pump. With the Hook connected we operated the pump to make sure all the air ports were able to blow a good stream of air. Check out these videos of the air pump and ports: https://www.youtube.com/watch?v=qEBlcNTjiVU, https://www.youtube.com/watch?v=mx5WpqPEEss.
After our successful test of the air ports we were able to install the exhaust manifold, starter, engine cradle, exhaust system and suspension components along with all new hardware. We started the BMW up and drove the vehicle for a week to make sure that the MIL would no longer illuminate. The 745i was now fixed and running well without the MIL illuminating.
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Living in a vacuum: Crankcase ventilation system testing
In this article, I will be talking about a subject that does not get much respect or attention amongst most automotive technicians and that is engine crankcase ventilation systems. Many technicians consider these systems to be pretty simple and trouble free but they are often overlooked in their importance as well as their ability to cause rather confusing problems on modern powertrain platforms. It is my goal to show you the importance of considering the crankcase ventilation system in your diagnostic routine and how to test crankcase pressure to determine if the system is working correctly.
Understanding crankcase ventilation
Crankcase ventilation is as old as internal combustion engines and has to be addressed in any modern, emission-controlled powertrain. Prior to federal emission control standards, the crankcase of an engine was vented to atmosphere through a component called a road draft tube. The tube was connected to the side of the engine block or valve cover and routed down to slightly below the bottom of the engine in the vehicle's slipstream. When the car was moving, air rushing past the tube would create a low-pressure area and fresh air would enter the engine through a breather that was usually the oil filler cap. This would allow the engine blow-by gases to be drawn out of the crankcase and vented to the outside.
While simple, there were problems. When the vehicle is not moving, there is no crankcase ventilation and when driven at high speeds, the system is too efficient and oil was drawn out of the engine along with blow-by gases creating a black, oily stripe down the center of the highway. But the main problem with this type of system is the release of unburned hydrocarbons into the atmosphere.
Crankcase emissions were considered one of the main causes of smog in the Los Angeles basin in the 1950s and ’60s. In 1961, Positive Crankcase Ventilation systems became mandatory in California and in 1964 all new cars were equipped with this system. PCV systems allow the combustion blow-by gases to be rerouted into the engine intake manifold to be burned with the incoming air/fuel mixture. These systems are basically vacuum controlled so there is less flow at low engine loads when blow-by would be less and greater flow under road load conditions when blow-by increases.
Many modern powerplants have done away with the common PCV valve and now utilize fixed orifice systems or an integrated flow control valve and oil separator. So much for the theory and history lesson, let’s see what goes wrong with these systems and how to test them.
Testing crankcase ventilation system function
The first indication that something may be amiss with crankcase ventilation is an excessive amount of condensation in the crankcase and this is commonly seen during an oil change by milky deposits found on the oil fill cap or seen inside the oil fill hole.
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| Figure 1 - Excessive condensation deposits from poor crankcase ventilation. |
The problems I am more concerned with is when crankcase ventilation problems create a “Check Engine” light concern which most often shows up as fuel trim codes. One particular vehicle comes to mind that was sent to me from another shop. The 2001 Chevy S-10 Blazer with a 4.3 VIN W engine had lean fuel trim codes set for both banks. There was a disconnected vacuum hose found but even after plugging the hose, the fuel trim numbers were very high at idle — each bank was positive 24 percent.
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| Figure 2 - Troubles codes stored on the Chevy S-10 Blazer. |
A new replacement mass airflow sensor had already been tried with no change in fuel trim values. Knowing that false air or unmeasured air can skew fuel trim, it was decided to disconnect the crankcase air inlet hose to see if the trim values changed at idle. They did not.
Crankcase air supply is provided after the mass airflow sensor so that this air is measured. If air is being drawn into the crankcase from a leak then this air cannot be measured and the system will be lean.
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| Figure 3 - PCV fresh air inlet hose can be seen connected to the throttle body snorkel after the mass airflow sensor. Disconnecting this hose at the valve cover caused no change in fuel trim values. |
One final check was made. A vacuum gauge was connected to the dipstick tube and the PCV fresh air inlet at the valve cover was blocked with the engine idling. The vacuum reading is shown in figure 4. Almost no vacuum was present indicating there is an air leak into the crankcase. When smoke from a smoke machine was added to the crankcase, the problem became evident. There was an improperly installed valve cover gasket on the passenger side of the engine. Replacing the gasket corrected the high fuel trim values.
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| Figure 4 - Crankcase vacuum reading with leaking valve cover gasket. |
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| Figure 5 - Leaking valve cover gasket on right bank of engine causing air leak into crankcase. |
This issue has played itself out many times on different vehicles and has caused a large amount of unnecessary parts replacement because many technicians do not look at crankcase leaks as a possible cause of fuel trim codes and do not measure crankcase pressure
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| Figure 6 - This is the vacuum reading after replacing the valve cover gasket, quite a difference! |
Pressure, vacuum or both?
While I have been mentioning measuring crankcase pressure what is normally seen is a negative pressure or partial vacuum. This is because a regulated vacuum is applied to the crankcase in order to draw out combustion blow-by gases. Keep in mind when taking crankcase vacuum measurements that the fresh air intake should be blocked off and that it will take a few moments for vacuum to build in the crankcase.
Do not let the engine run for more than a short time once the vacuum gauge settles to a stable reading as excess under-pressure or over-pressure may damage some seals or gaskets!
This brings to mind some more theory on crankcase pressure. I remember purchasing a tool long ago from my Snap-on supplier called a MT-383 Blow-by tester. This tool measured the amount of blow-by gas flow leaving the crankcase. The PCV valve was removed from the valve cover and the flow meter installed in its place. The fresh air inlet was plugged and the engine ran at both idle and high speed. The clear, graduated flow meter measured flow in standard liters per minute.
The theory is as an engine wears out, especially from piston ring and cylinder wear, there will be an increase in crankcase pressure due to greater blow-by and this can be measured to determine wear. This leads to the issue that there can be both a crankcase over-pressure condition as well as an under-pressure condition. If engine wear causes too much crankcase pressure it will overwhelm the PCV system and lead to excessive oil leaks. Excess crankcase pressure may also occur if the PCV system vacuum supply becomes restricted. Excessive crankcase under-pressure, (vacuum) can occur if the fresh air inlet becomes restricted or the wrong PCV valve is used.
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| Figure 7 - Snap-on blow by meter connected to a Chevy V8 engine. |
Turbos and crankcase ventilation
When a turbocharger is added to the engine the crankcase ventilation system becomes somewhat more complicated due to the fact that the routing of crankcase blow-by gases has to change when the engine is under boost pressure due to a lack of intake vacuum. I will use a case study from a turbocharged BWM to illustrate this issue.
Speaking of BMWs, these vehicles clearly display the need to measure crankcase pressures when driveability problems arise. Unlike many vehicles, late model BMW’s with Valvetronic intake valve lift control have a regulated intake manifold vacuum. The target vacuum level on any BMW Valvetronic engine is only 50 millibar or about 1.5 inches of mercury. With this small amount of vacuum available, crankcase pressure is closely regulated and can have a major impact on how these engines run at idle.
I use a Dwyer series 475 digital handheld manometer to measure crankcase pressure on most European cars and any BMW vehicles. The tool measures pressure in inches of water column but this is easily converted to millibar which is the spec given by BMW. The adaptor seen in the picture is available from a company called AGA tools, or you can make a test adaptor from and old oil cap. There is a service bulletin, #11 05 98, which details testing crankcase pressure on BMW vehicles. I highly recommend printing this out and keeping it handy if you work on these vehicles.
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| Figure 8 - Crankcase pressure measurement on a BMW X-3, N52 engine |
Not only can you measure crankcase pressure with a vacuum gauge or manometer, you can also use an accurate pressure transducer such as a Pico WPS500 to measure crankcase pressure with a scope. A scope and pressure transducer may also be able to show pressure pulses inside the crankcase that can be caused by excessive cylinder wall to piston compression leakage that escapes into the crankcase.
Figures 9 and 10 show a crankcase pressure test performed on a 2016 BMW X-5 with the N55 turbo-charged six-cylinder engine. The bottom waveform is crankcase pressure and the upper waveform is cylinder #1 ignition coil firing so you can see when the engine was started and shut off. The time-base is quite slow at 10 seconds per division. When the engine is shut off it takes an amazing 75 seconds for the pressure to return to atmospheric in the crankcase. That is a tightly sealed crankcase!
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| Figure 9 - Using a Pico scope and pressure transducer to measure crankcase pressure on a 2016 BMW X-5 with the N55 engine. |
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| Figure 10 - Scope capture of crankcase pressure pulling into a vacuum after the engine is started. When turned off there is a slow rise back to atmospheric pressure. |
I must also mention here that while the BMW TSB is mostly concerned with too much pressure, or a lack of vacuum in the crankcase that indicates a leak, there is also the problem of too much vacuum! Many engine faults on a BMW Valvetronic engine can put the engine in throttle control mode and the intake manifold vacuum will be very high, like a conventional engine. The crankcase ventilation system is not designed for high manifold vacuum so the crankcase negative pressure will be very high as well. If you encounter an oil fill cap that is nearly impossible to remove with the engine running, or a high-pitched whistle while the engine is running check for faults that are preventing normal Valvetronic operation.
A few BMW case studies
An interesting problem vehicle was brought to the shop that clearly illustrates the need to check crankcase pressure. The vehicle was a 2007 BMW X-3 with the N52 six-cylinder, Valvetronic equipped engine. The complaint was a severe idle surge that would also cause the engine to stall at idle randomly.
The engine would run alright when driven at cruising speeds. When first checked there were 14 engine control related codes. All four oxygen sensor heaters set codes, there was a Valvetronic servomotor sluggish movement code, all six cylinders set misfire codes and there was an air mass system code and a cold start idle speed plausibility code. With so many codes it is difficult to determine where to start. Codes were cleared and a Valvetronic limit learn procedure performed and then the engine was allowed to idle for several minutes. There was no change in engine idle and codes reset quickly and can be seen in Figure 11.
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| Figure 11 - Screenshot of codes that reset on the X-3 after running several minutes. |
After looking at Valvetronic eccentric shaft data it was noticed that the eccentric shaft position was wandering back and forth and this will most certainly cause the engine speed to surge. The question is why can’t the DME control idle speed properly?
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| Figure 12 - This is the crankcase pressure measurement on the surging BMW X-3. |
An air leak can certainly have an effect on idle speed control but before pulling out a smoke machine to check for intake system leaks, a crankcase pressure measurement is performed first. The result is a failed test - the crankcase pressure wanders between -2.5 to 4 inches of water column. This is a range of -7 to 10 millibar, well below the specification for this engine which is -30 millibar, plus or minus 5 millibar. If there is less vacuum in the crankcase, this would be an over-pressure condition which means air is leaking into the crankcase.
This false air is not measured by the mass airflow sensor. A smoke machine was connected to the same test fitting used to measure crankcase pressure and smoke began to pour out from behind the engine crankshaft pulley. Upon pulley removal, the damaged front crankshaft seal was obvious. The seal was damaged due to a serpentine drive belt failure which is a common problem on these platforms but nobody bothered to tell us the belt had recently failed. After replacing the crankshaft seal the engine ran normally even though the oxygen sensor heater issue was not repaired! The customer simply had enough and was told the engine may suffer catastrophic failure if there is more drive belt material still inside the engine. Of course, they stated they were trading the vehicle in.
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| Figure 13 - Old drive belt material being pulled from behind the damaged crankshaft seal. |
A very interesting problem was seen on another BMW car that was diagnosed for another shop who stated the 2011 BMW 335xi was brought into their shop due to a failed OBD state emission test. The shop was chasing down a generic code P112F, or a BMW code 28A0. The BMW code is for intake pipe absolute pressure, plausibility, pressure too high, the generic code description is a throttle angle to manifold pressure correlation problem.
These code descriptions do not lend themselves to a quick understanding of what is wrong with this vehicle. After changing the throttle body and intake pressure sensor the codes remained. A tech hotline told the shop to perform a re-learn by running the engine at idle for 15 minutes with the vapor canister purge valve disconnected. This did not cure the issue. At this point I was asked to come take a look at the vehicle.
The factory ISTA scan tool description for a 28A0 code stated an interesting bit of information that had so far been overlooked and is shown in figure 14.
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| Figure 14 - BMW 28A0 code description information found in the factory scan tool |
The statement underlined mentions that the fault is recognized when the monitored mass flow rate rises above a limit value. This means that there is too much airflow being measured for the commanded throttle position. This statement effectively rules out any false air leaks into the intake system such as a leak in the intake manifold or any turbocharger plumbing. If there is too much airflow the mass airflow sensor has to be able to measure it so I am looking for how this could be possible. As you should suspect by now, I decide to perform a crankcase pressure test.
The pressure measures -7 IWC or -17 millibar. This pressure is too high and indicates a leak into the crankcase. The arrow in figure 15 points to a crankcase ventilation hose that connects to the turbocharger inlet pipe. This is downstream from the mass airflow sensor and airflow through this pipe can be measured by the MAF. The scan tool test plan for this code mentions to check for air leaks first and check the crankcase ventilation system next, see figure 16.
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| Figure 15 - Crankcase pressure test on 2011 BMW 335xi with code 28A0. Reading is equal to 17 mb, too much pressure in crankcase meaning a leak is present. |
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| Figure 16 - Scan tool test plan screenshot listing items to test for code 28A0. Number 2 is a crankcase ventilation check. |
After carefully removing the breather hose at the valve cover and plugging the hole with my thumb the crankcase pressure drops significantly. The pressure can be seen in figure 17.
This hose connection is used to vent crankcase vapors into the incoming airstream when the engine is operating under boosted conditions. There should be no airflow through this tube at idle. A look at the crankcase ventilation diagram found in a BMW training book shows how the system operates in normal load and boost conditions when pressure is present in the intake manifold instead of vacuum. Item number 12 in the diagram is a non-return valve that opens during turbo boost operation. This is a normally closed valve but it is stuck open on this BMW.
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| Figure 17 - Plugging off crankcase breather hose used when car is under boost conditions. |
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| Figure 18 - Crankcase ventilation system diagram for this BMW N55 engine. Courtesy BMW. |
The repair on this BMW was replacing the valve cover with a new part, the valve cover contains most of the components of the crankcase ventilation system. One last item to mention about this issue can be seen from the test plan information about this code seen in figure 19.
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| Figure 19 - Screen capture from BMW listing the “Action in Service” items and the fact that the effect of the fault is “none.” Note that the “Driver Information” is the illumination of the emissions warning light. |
The bottom two items mention replacing parts, this is what will draw the attention of most technicians. The top item states to check for air leaks in the intake system and crankcase. If you do not have a means to test the crankcase for leaks, this step is most certainly overlooked or bypassed entirely. I hope this discussion of crankcase pressure measuring helps you to diagnose some troublesome drive-ability issues and adds another test to your diagnostic toolbox.
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PEAK launches new high-performance extended life antifreeze and coolant
Old World Industries, a leader in the manufacturing and distribution of high-quality automotive and heavy duty fluids, announced the launch of its new PEAK® Antifreeze + Coolant, designed with an advanced formula that guarantees superior lifetime protection.*†
The introduction of the new PEAK marks Old World Industries’ first major launch in the extended life antifreeze/coolant segment in more than a decade and is the result of extensive research to understand the Do-It-For-Yourself (DIY) consumers’ needs and purchase decision process.
“Our new PEAK meets the needs of consumers that desire a high-performance antifreeze/coolant,” said Charles Culverhouse, CEO of Old World Industries. “Our advanced formula guarantees superior lifetime protection, giving consumers peace of mind.”
The new PEAK Antifreeze + Coolant is specially engineered with an advanced proprietary formula which includes a combination of scale-fighting inhibitors and organic acid corrosion inhibitors that guarantees Superior Lifetime Protection†* against scale and corrosion. Scale can form in the cooling system from poor quality water or from corrosion products forming on surfaces. These deposits can reduce coolant flow in the radiator and other parts of the cooling system, significantly reducing heat transfer and leading to the engine overheating. A build-up of only 1/16-inch of scale can reduce heat transfer by up to 40%.‡ New PEAK Antifreeze + Coolant contains ten times the scale-fighting inhibitors* and provides more than two times the warranty coverage** for a minimum of 10 years/300,000 miles of maximum cooling system performance.†*
The launch of new PEAK Antifreeze + Coolant coincides with a recent expansion of PEAK Original Equipment Technology Antifreeze + Coolant availability, which is now carried in over 30 retailers including AutoZone, Advance Auto and Pep Boys.
New PEAK Antifreeze + Coolant is designed for use in all North American, Asian and European passenger cars, SUVs, motorcycles and light/medium duty trucks, regardless of make, model or year. Its universal formula is compatible for use with any type of antifreeze/coolant and its amber-yellow color will not change the color of the coolant in the system. To learn more about the new PEAK Antifreeze + Coolant and other PEAK products, visit peakauto.com.
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Ingersoll Rand introduces new subfreezing dryer with breakthrough refrigeration technology
Ingersoll Rand®, a global leader in compressed air and gas systems and services, has introduced its new breakthrough dryer technology, the Subfreezing Dryer.
By incorporating its 146 years of engineering expertise and heritage, Ingersoll Rand has designed a dryer that is the first of its kind. The Subfreezing Dryer is the world’s first dryer that provides -4 degrees Fahrenheit pressure dew point at 70 percent lower energy costs and 40% smaller footprint than that of traditional desiccant dryers. Ingersoll Rand’s new Subfreezing Dryer is compatible with oil-flooded rotary compressors, oil-free rotary compressors, centrifugal compressors and reciprocating compressors.
“The new Subfreezing Dryer achieves class leading air quality, previously only attainable with far costlier drum or desiccant dryer technology. We have developed new technology that provides our customers with high quality, -4 degrees Fahrenheit dew point air, from a high performance regenerative refrigerant dryer in an efficient and economical package,” said Nathan Blasingame, Global Portfolio Leader for Air Treatment and System Components for Compression Technologies and Services at Ingersoll Rand. “This breakthrough technology provides very dry air without wasting energy or purging compressed air; customers have the full capacity of their compressor.”
The Subfreezing Dryer supplies a constant ISO Class 3 -4 degrees Fahrenheit pressure dew point air, regardless of changes in demand or ambient temperatures. This allows customers to dependably meet the compressed air needs of their operation.
“Whether customer’s needs are general purpose, or they are manufacturing critical products such as pharmaceuticals, the Subfreezing Dryer delivers the air quality they need,” Blasingame said. “The high-efficiency, superior operating cost alternative – Ingersoll Rand’s groundbreaking Subfreezing Dryer – provides real customer value.”
The Subfreezing Dryer has a lower total cost of ownership than traditional regenerative desiccant dryers and has an 80% lower maintenance cost than drum dryers. Unlike drum and desiccant dryers, there is no costly periodic desiccant replacement, and with no desiccant required, downstream particulate filtering is not needed.
For more information on the Subfreezing Dryer, visit IngersollRandCompressor.com or contact your local service representative.
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When the automotive classroom spans the Atlantic
I have a lot of people to thank for being in my corner. My entire life consists of memories where people have been supportive of me, every step of the way. Whether it was from family, friends, co-workers or even personal mentors of mine; I’ve always had a guiding hand. Many doors have opened, as a result of efforts from people like the ones mentioned. My very first class (written on my own) was written to demonstrate the implementation of an unconventional testing method. One that many have found to be helpful to efficiently diagnose engine mechanical faults without expensive/time-consuming disassembly. The class has gained traction and popularity around the world and has brought me to the United Kingdom. That is where an opportunity of a lifetime had opened for all of us diagnosticians and will forever change the way we train in the automotive industry.
A flame has been ignited
It all started a few months ago (if you’ll recall) when I assisted a young, talented technician in the UK named Ryan Colley (see this article). I applied the techniques I teach in class and helped Ryan condemn the timing components of an engine without the need to disassemble. He thought this could be beneficial to his peers in the UK and invited me to deliver the class in person. Tremendously excited, I agreed to do so and the plans began to fall in place. Little did I know, we would be making history. We traveled the country, beginning in the south in the village of Taunton, Somerset, UK. There is where I met one of the UK’s finest instructors, Mr. James Dillon, who was kind enough to offer his phenomenal training facility (known as Tech Topics Head Quarters) to host my debut class. The class was a great success and I was very much looking forward to our tour of this fine country as well as the two other classes, scheduled for the remainder of the week. I also must take a moment to publicly thank James for the wonderful hand-made cheese, whiskey and beer he sent me home with, as a token of memory. It was very much enjoyed!
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| What an honor meeting two of the UK's best: Frank Massey (left) and his son, David (right). |
Establishing brotherhoods and future gatherings
Now, as exciting as the classroom was for me, I simply can’t discount how much fun we have had behind the scenes. Traveling with me and accompanying me the entire time were my newest brothers (“me Mates”) Ryan Colley and Steve Scott of Simply Diagnostics (check out his channel on YouTube), one of the UK’s finest mobile diagnosticians and popular YouTube contributor. I’d compare him to the likes of our own John Anello (Auto Tech On Wheels). Equally as clever and even more hysterical! These guys were an absolute necessity to the success of the trip and it simply could not have occurred without their hard work and dedication to our industry.
Before hitting the open road, we enjoyed some food and beer with some phenomenally talented technicians. It’s little places, like the pub we chose, where I met techs like Adam Critchley, (better known as “The Critch”) where I witnessed him eat his own bodyweight in burgers and fries. He is a real sharp guy underneath his layers of muscle and body mass. Likely one of the most colorful characters I encountered on the whole expedition. I met his best friend, Neil Curry who, like “Critch,” holds the coveted title for "UK’s Top Automotive Technician!" What an honor!
We had a day’s rest and enjoyed visiting places like The Tower in Blackpool where we stood about 400 feet above the ground, standing on a clear-glass floor. Of course, Steve had to test the limitations of its integrity by jumping up and down, with us all on it! We also celebrated “Chippy-Friday,” a bit too soon (but how can you visit UK and not have a proper “Fish-n’-Chips with Mushy-Peas?”). All in great fun, Steve even sent me home with a souvenir for my little girl, Makenna (a.k.a “The Bop”). We made our way up the western coast of England to the central part of the country, where the next venue was located and had a fantastic time with some of the attendees that would be present tomorrow. This is where I learned to properly drink a Guinness! From the first initial sip, the surface of the beer must then rest between the word “Guinness” and the crest etched into the glass. That was a blast!
Star struck
On the day of my second presentation, we set up class in a beautiful shop in Preston, Lancashire. Automotive Diagnostic Solutions (A.D.S) was the venue and home to (and where I was greeted by) one of my heroes and his son, world renowned diagnosticians Frank and David Massey of AutoInform Magazine. The shop was fully prepared and specialized in the performance tuning of exotic machines from all over Europe. The place was extremely impressive. Frank even cut his Alps motorcycling tour vacation short, just to rush home and be a part of class. What an honor it was to be in the presence of such greatness and be treated like a peer. That was easily one of the greatest experiences of the entire trip. Not only was class a huge success but the downtime at the local pub left my face in pain (from laughter) and some brilliant lasting memories. David has since become like a brother to me; and I can’t forget to mention his darling assistant, Annette Parkinson (the true boss). What a tremendous asset she is and so willing to help. I’m a huge fan of hers.
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| Nothing like applying what you learned! And with brothers from "across the pond!" |
On the third and final venue, we finished the tour in Glasgow, Scotland where class was held in the BOSCH training center. I met the likes of so many talented individuals, including some of my favorite mates, Craig Overfinch (and his lovely wife), Tommy Forrest, Stephen Marshall (and his cute little daughter) and “Joey Vauxhall” (you guessed it, a Vauxhall specialist). Joey took us all out to dinner to a restaurant owned by one of his closest friends. He wanted my first trip to UK to include healthy helping of Haggis, prepared as many ways as you can imagine. Honestly, it was quite nice! Another wonderful class experience was carried out and the following day, spent the afternoon applying what we’d learned in class, hosted by Craig in his workshop called Phillips Garage. There I experienced a live, diesel-powered Vauxhall, where we successfully diagnosed a valve seating issue using some unconventional methods. Not one day goes by that I don’t miss each one of those fellas.
The classroom has spanned the Atlantic
As important as this experience in the UK was to me, regarding the brotherhoods formed and the experience of how things are done on that side of the great Atlantic; the most important part would be the fact that we have successfully bridged the gap between the U.S. and UK. A kinship has been established and some very important phone/email conversations have occurred. I’ve been in exchange with some of the United States’ best instructors and all are excited to carry their knowledge across the ocean in the near future, as I have. On the flip side, both Frank Massey and James Dillon have both given me their blessing and agreed to teach here in the U.S. as well! Most impressively, this month, ASA is hosting an event in the Philadelphia-area of Pennsylvania called Super Saturday and I am happy and proud to say that SEVEN of our UK counterparts are scheduled to arrive and attend the one-day event.
We have started a new culture of exchanging the way we do things over here (in the U.S.) and the way they do things over there (in the UK). With my short 20 years’ experience in the industry, I can tell you that these UK technicians are some of the most talented and intelligent I’ve ever encountered. The training and certification they implement “over there” is extremely impressive and all of us here can stand to learn a lot from them. It’s all thanks of the incredible efforts made by that brave young man, Ryan Colley, who put a lot on the line to take a chance on me. As a result of his efforts, we have him to thank for what has occurred between these two great countries of ours. From this point forward, I will always refer to Ryan as “The Gatekeeper.” I truly hope the nickname sticks, because that is exactly who he is. We’ve made it to the UK…where will it lead us from here? The world is the limit!
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A PID-o-full diagnosis on a 2008 Ford F-250
Those of you that have come to know me are aware that my experience with diesel drivability concerns is extremely limited. For good reason though. I’m not properly equipped to take on the job efficiently and don’t see a need to take myself in that direction. With that being said, when an opportunity arises to get involved with a job like that, I’m happy to provide a set of eyes for evaluation. I’m always in mindset to learn something new, to broaden my skillset and to allow me to aid and support others. For years, I’ve had the attitude that if I have fundamental knowledge of how a component is designed to work, information supporting how a system strategizes to carry out a goal and a thorough understand of the limitations my tools/test procedures provide, I can solve any issue.
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| 2008 Ford F-250 |
The unfamiliar adversary
This case comes to us from a great friend and co-instructor of mine (with CarQuest Technical Institute) Brent Delfel, of Advanced Diagnostic Consulting in Snohomish, Wash. Brent was called to a jobsite with the complaint originating from a 2008 Ford F-250, equipped with a 6.4L diesel engine. It seems upon initial start-up, there is a noticeable hesitation upon acceleration. This fault vanishes shortly thereafter but symptoms will return each time the engine is shut-down and re-started. Brent gathered some data, first with a basic scan tool and then the result of the PIDs led him to pinpointed scope testing. Brent had a theory and asked for my input. He sent the captures to me for evaluation and well…. here we are.
The elementary approach
For me, it always starts at the beginning. Particularly, when I’m dealing with the unfamiliar. This is what I’ve learned about this common rail diesel fuel system:
Diesel fuel is carried from the fuel tank through a fuel conditioning module where fuel is filtered and pressurized (to about 3-8 psi). It is then sent to the engine compartment where it is once again filtered before entering a camshaft-driven, high pressure fuel pump assembly. The HP fuel pump is capable of outputting pressures exceeding 24,000 psi! Some of the diesel is used to simply cool and lubricate the pump assembly. The pressure is sent from the pump to parallel standing injector rails (one per bank of the engine). The pump’s pressure output is grossly controlled by a fuel volume control solenoid and curtailed further with a fuel pressure control solenoid. Both are controlled by the PCM to maintain swift and accurate control of the pressure within the fuel rails. When pressurized diesel leaves the pump, i'ts routed to the injectors. Pressure in the injectors is equal on either side of a nozzle needle. When the injector is commanded to fire, a pressure differential takes place within the injector and a control piston initiates delivery of a highly vaporized/atomized mist of diesel to the combustion chamber. The small dose of fuel being displaced to generate the pressure differential is referred to as “return fuel”. This is because this volume of diesel is recirculated back through the low-side fuel system to start the process over again.
I apologize as that system description/operation was a bit lengthy but there is a method to my madness, and it will all come together in the end.
Let the games begin
Now, having a brief overview of how the system is constructed and what components are operated as a strategy to control the diesel injection system; It’s time to come up with a game plan. This game plan will vary on any vehicle or problem you are encountering but the object of the game plan is ALWAYS the same. How can I test most efficiently to give me as much information with as little time invested as possible? This depends a lot on how accessible components are for testing, what tools I have at my disposal, and how capable my available scan tool is, along with the robustness of the PCM’s software (what information is it willing to give up in a PID list).
So, recalling that I’m viewing this from the other side of the country, I’m limited to viewing only what data has been captured. Let’s begin at what I call “the low hanging fruit.” Information like this is very easy to obtain, usually right from the DLC and answers a few basic questions for me. In this case:
-What am I “feeling” from the driver’s seat (the symptom/ customer-concern)?
-What is causing the concern (incorrect fuel delivery)?
-Is the problem being seen and compensated for by the PCM (control issue or mechanical fault)?
The significance? The answers to those questions can be seen easily in the PID list on even a basic professional scan tool. More importantly, the answers to those questions will point me in the direction of testing in which to deploy. Every step taken from this point forward will be justified and will lead to yet another conclusive answer on which component or part of a system to test next. The PIDs chosen to monitor were:
-Desired Fuel Rail Pressure
-Actual Fuel Rail Pressure
-Fuel-Volume Control Solenoid
-Fuel Pressure Control Solenoid
As mentioned above, these PIDs will tell me if what I’m feeling as a symptom is due to a fuel delivery issue and why. It will also tell me if the PCM is seeing what I feel and trying to fix the issue. Looking at PIDs in a graphed format offers some distinct advantages over numerical forms of data analysis. The graphs not only allow the viewer to see a history of the PID but also allows for a comparison of multiple PIDs simultaneously. This provides for the action/reaction point of view. A means to see a fault present itself and a PCM’s response to the fault. Unfortunately, the available scan tool chosen isn’t capable of graphical formatting; meaning, we can only look a numerical value at a single moment in time. This provides for a disadvantage. But all is not lost.
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| Figure A |
“Excel” to excel
Although the scan tool isn’t capable of graphing, Brent simply took the data from each individual frame captured. He then uploaded these PIDs over time into a Microsoft Excel graph program. If you refer to Figure A, the fault as well as the computer’s reaction is visible. The graph clearly displays a severe lack of fuel pressure along with the PCM’s command to increase fuel volume to the rail and boost pressure. This means the rail lost pressure and the PCM tried to fix it.
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| Figure B |
So, referring to Figure B, we can see the lay of the land regarding the entire HP fuel system. HP pump assembly, I have surrounded by a red square. Within that is the pressure control valve, surrounded in the green square and the volume control valve surrounded by the blue square. Both these components are self-contained within the pump assembly. The highly pressurized diesel leaving the pump travels in Red through the rails and to each injector. Pictured in Figure C is the return fuel system. Light blue represents the lube/cooling fuel from the HP pump, the return fuel from the left cylinder head and the return fuel for the right cylinder head. They join together in a “T” and enter a return fuel cooler. This cooler has a test port making pressure samples available to us.
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| Figure C |
After analyzing the graphed PIDs, it’s time to pinpoint the location of the fault. We should all understand that the HP system can only function properly if it receives a healthy supply of low-pressure fuel from the low-pressure pump and filter assemblies. This was verified by Brent with a pressure test under load when the fault occurred. Brent “tee’d-in” to the low-side supply line leading from the fuel conditioning module to the filter module. There was no decay (exceeding specification) of low-pressure fuel during the exhibited symptom. So, logic will tell you that we can eliminate the low-side fuel system as a contributor to this fault. The focus will be on the HP side of the fueling system only…and the only test we performed was by placing a gauge on the low-pressure side. Not a lot of time/energy invested at this point. Eluding to the fault being on the HP side left a few items as potential failure-points. The pump itself could surely be at fault, but so too could it be any of the injectors. Now, the nature of the HP leak would tell us if an injector was over delivering, as we should see this reflected in the smoke bellowing from the tailpipe. This vehicle DID NOT experience this fault. If the injector was leaking to the crankcase, we should be seeing evidence of that in the oil but that too revealed no evidence of diesel contamination. However, the injectors could be leaking excessive fuel back to the return-side of the system. How could we tell? Even if there was no specification found for this type of test?
Let’s scope it out
I’ve mentioned many times before that having a thorough understanding of the tools you use makes that tool an extension of your mind. It allows you to make inquiries of the components you desire and offer you the ability to evaluate an entire system dynamically. With that notion in mind, Brent deployed the scope to monitor the action/reaction display of the system when it is malfunctioning. Looking at Figure D, In RED is the signal from the fuel rail pressure sensor. In green is a pressure transducer connected to low-side fuel supply system. The black trace is a math-channel on the scope. It is a derivative of fuel volume control solenoid command and is displayed in “duty-cycle percentage.” It represents the PCM commanding more fuel pressure generation. The story told by the capture is that under high demand situations that we placed the vehicle under, the PCM commanded a high amount of fuel volume to the HP pump. This allowed the HP pump to produce a steep increase in pressure, as it should. The lack of performance from the engine could be felt, meaning the fuel never made it to the cylinders. Now, the loss of low-side supply typically causes a loss in HP output. It did not do so in this case. (Further explanation to follow). Clearly the HP pump could produce the pressure so why didn’t it make it to the cylinders? This is the question that will be answered in the next justified test.
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| Figure D |
Look at Figure E. In blue is the injector current trace from injector #1 only. It is used simply as a point of reference along with the firing order. This will indicate which injector was firing at any given point in the engine cycle. You can see I’ve annotated the top of the capture to show the firing order and partitioned the capture eight different ways, to represent each of the eight injectors firing. In red is a pressure transducer on the fuel cooler test port to represent pressure on the return-fuel side of the system. This is a zoom capture to represent one engine cycle and is displays a variation in pressure, on the return fuel side, comparing each injector’s firing to the other seven. What isn’t important is the actual pressure value (not that we found a documented specification, anyway). What is important is the fact that the injectors don’t return the same amount of fuel when they de-energize.
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| Figure E |
It’s the combination of the captures that tells the entire story. The PIDs reflected a lack of fuel pressure when it was commanded and that the PCM was trying to compensate. A test of the low-pressure system was carried out and displayed the ability to delivery pressure under high-demand situations, allowing the HP pump to do its job. Although the low-pressure side of the system dissipated under load, it stayed within specification. The big increase in HP pump output (to pressurize the rail adequately and overcome a leak to the return-side was like turning on a faucet) caused the depletion in low-pressure supply. A lack of performance proved the fuel never made it to the combustion chambers and the final capture told us why. Under high demand situations (when the symptom occurred) the return fuel pressure increased for all injectors except for two of them (#3 and #8). The HP pump made the pressure but instead of delivering to the combustion chambers, six (of the eight) injectors dumped the fuel to the return-fuel system, condemning the injectors as being mechanically faulty. A specification for return-fuel pressure wasn’t needed. The process of elimination determined where the fault lay.
Waiting to exhale
Now, it is almost unheard of, for me to make a claim like the above without having concrete-proof of a fix. Unfortunately, the customer chose not to invest the money in the suggested replacement of the all eight injectors. There is still some take-away from this case-study. The story never changes, just the characters…have a thorough understanding of components/system’s functionality, understand the basic-fundamentals and the limitations of the tools/test you implement and there are very few tough-to-find faults you won’t make quick work of.
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Troubleshooting exhaust restrictions
A few years back I had a customer that parked their car in a barn for almost a year. This particular customer stored his vehicle because he was deployed to Afghanistan with the U.S. Army. Being an Army veteran myself, I felt the need to help this individual out. The Ford Focus that I had to deal with exhibited a crank no start condition. It is not uncommon if a vehicle stored in a barn, for those of us that are used to rodent damage, to exhibit this complaint chewed wires. Some initial checks were made including checking DTC’s and a quick visual inspection. No obvious faults, including nesting material or damaged wires, were found. After pumping the last few gallons of old gasoline out of the fuel tank and adding some fresh gasoline, the engine started to sound like it was trying to fire. After some additional cranking and exercising the throttle, a weird “pop” was heard and the engine roared to life. However, it still did not have the most desirable acceleration even in the shop. I found out what the “pop” was when I walked around the back of the vehicle and saw a shotgun blast of four or five mouse carcasses scattered about three feet behind the tail pipe. Who knows how many more mice, nesting material, feces and food stash still remained in the muffler? I really didn’t want to run the vehicle for too long and smell what was left cooking in there. My guess is that would have been an unpleasant odor that might not leave the shop for a week. The decision was made to replace the muffler, which was quite heavy by the way, and the car ran fine.
The Focus did not have a typical exhaust restriction. The most common cause of a restricted exhaust is a failed catalytic converter. However, the testing techniques covered in this article will identify the issue regardless of what the restriction is. In most exhaust restriction cases the vehicle will still run but exhibit low power complaints and, if the restriction becomes bad enough, the vehicle may also exhibit misfires.
In order to diagnose a restricted exhaust, I follow a logical process that consists of basically two steps. The first step is to perform a test drive while recording some data for analysis. If a restriction is suspected, the second step is to confirm the restriction using one of a few possible physical testing methods. Let us attack these two steps individually.
The test drive
Before performing any intrusive testing, a scan tool (preferably one with good graphing capabilities) is connected and the vehicle is taken for a test drive that includes some normal driving and a wide-open-throttle portion. A handful of data PID’s are chosen and recorded. These PIDs include: RPM, MAF, O2 sensors, short term fuel trim and long term fuel trim. If you are familiar with how the particular vehicle displays its Load PID then it can be used as well. Upon return to the shop the data that was recorded can now be analyzed.
The first thing to check is the volumetric efficiency, or VE, of the engine. This is basically a measure of how well an engine can breathe. This topic has been covered in previous Motor Age articles but can be summarized as follows: MAF and RPM are noted near the peak of the wide-open-throttle portion of the test drive. These two numbers are entered into a VE calculator, along with engine displacement, and a VE number is calculated. For naturally aspirated applications we would expect somewhere around 80% or higher if the engine can breathe efficiently. A VE number in this range indicates that the exhaust is not restricted because the engine can effectively “exhale.” On the other hand, if our VE is low, then more of the recorded data PIDs need to be observed. Note: This is also where a LOAD PID can be used if you know what is known good for the vehicle being tested. If you don’t know what a good LOAD number is for the specific vehicle, the VE will still work the same for almost all naturally aspirated applications equipped with a MAF sensor.
Next, provided we have a low VE number, the oxygen sensors are observed during the wide-open-throttle portion of the drive. With a restricted exhaust the oxygen sensors go rich when the vehicle is floored. The amount of air flowing through the engine is less than it should be but is still being measured accurately. The PCM is still injecting the appropriate amount of fuel for the given air mass measurement and the oxygen sensors report accordingly… rich. If the oxygen sensors report a very lean condition then the fault is most likely not a restricted exhaust. In that case we would suspect another culprit such as a MAF sensor or other air metering fault.
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| Figure 1 - Scan data recording while test driving a vehicle with a restricted converter |
Figure 1 is a scan data recording of a 3.5 liter General Motors vehicle that exhibits low power due to a restricted exhaust. Engine RPM (red) is shown so we can see where the wide-open-throttle acceleration occurred. The oxygen sensor (green) does in fact go rich under load. Figure 2 shows a VE calculation, from the same test drive, of 60 percent which indicates the engine cannot breathe.
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| Figure 2 - Exhaust restriction causing poor Volumetric Efficiency |
Finally, as a bonus, fuel trim numbers are observed when the vehicle is operating in closed loop. Exhaust restrictions have little effect on fuel trim numbers unless there are two banks with two catalytic converters. In that case, if one converter was restricted, the fuel trim numbers from bank to bank will move in opposite directions from one another. If the low power complaint were to be caused by a failed MAF sensor, or weak fuel delivery, then our trim numbers would climb higher and higher into the positive range. In the previous example fuel trim numbers were slightly negative but still within an acceptable range.
To summarize the data analysis: if the VE measurement is low, the oxygen sensors display rich and fuel trim numbers are not ridiculously positive then a restricted exhaust is suspect. Once we have analyzed the data, and our conclusions strongly suggest a restricted exhaust, it’s time to get dirty and confirm our hypothesis.
Physical testing
There are quite a few methods used to test for exhaust restrictions. Some are better than others. They will be covered one by one.
Drop the exhaust and drive the car
This method to me is pretty “shade tree” to say it politely. It involves disconnecting the exhaust before the catalytic converter and test driving the vehicle again to see if power returns. Although this technique is somewhat effective, it can be labor intensive and will definitely be very loud during the drive. I think there are better options.
Vacuum testing method
This method involves connecting a vacuum gage to the intake manifold and revving the engine up while observing the gage. I believe this test is flawed because an exhaust would have to be extremely restricted to see any discernable change in manifold vacuum. Again, I feel there are better, and more accurate, methods of proving our hypothesis.
Backpressure at the O2
This technique is the most common test that has been used by technicians for many years. It requires either a dedicated backpressure tester or some creative connections with tooling you may already have. This creative tooling includes a compression gage hose and a standard vacuum pressure gage. If present, the Schrader valve should be removed from the compression hose and the gage can be connected to the end of the hose with a piece of vacuum line or similar tubing. Effectively you are building your own backpressure gage.
The backpressure tester, dedicated (Figure 3) or homemade, is designed to be screwed into the oxygen sensor mounting bung just before the converter. The vehicle is started and the throttle is snapped. A good vehicle should have little or no backpressure which indicates that the exhaust is freely exiting the engine and exhaust system. If the backpressure gage spikes 4 psi…10 psi…or sometimes even worse, then an exhaust restriction is present.
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| Figure 3 - A backpressure gage installed in place of an oxygen sensor to perform a backpressure test |
There are some problems with this test. First, access to oxygen sensors on some vehicles can be very difficult and time consuming. Second, if you live in an area that is prone to rust, removing the sensor can be even more difficult and can result in thread damage of the mounting bung, oxygen sensor or both. Again, more time consumption.
However, this test does have an advantage over some of the testing that will be covered shortly. If this test is repeated with the gage connected to the downstream oxygen sensor location and the results indicate high pressure then the restriction is further back in the system and not the catalytic converter.
Backpressure with a drill
This technique works exactly the same as the previous method but requires the technician to drill a hole in the exhaust ahead of the converter, install an adapter and connect the backpressure gage. Although this test allows easier access, it requires damaging the exhaust and then an additional repair after the test is complete.
In-cylinder
This test is by far the easiest to perform in my opinion. It does require the use of an oscilloscope and a pressure transducer. It also has an advantage that I believe is extremely valuable: ease of access to a test point. The only component we need to access on the vehicle is a spark plug. I know that some spark plugs can be located in some difficult spots, but it has been my experience that it is almost always easier to get to ONE of the spark plugs opposed to an oxygen sensor. In addition, unlike oxygen sensors, spark plugs almost always come out. Unless you are working on a 5.4 liter 3 valve Ford… but I digress.
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| Figure 4 - A pressure transducer installed in place of a spark plug to measure the pressure in the cylinder. |
To perform the test a pressure transducer is installed in one of the spark plug holes as shown in Figure 4. Either disable the spark for that cylinder or install a spark tester and be very careful not to expose the pressure transducer to the resulting secondary voltage. Some of the transducers on the market do not like to take a 60 KV hit and I would hate to damage a potentially expensive piece of diagnostic equipment. Next, the engine is started, a throttle snap is performed and the resulting pressures are observed on an oscilloscope. In order to explain how a restricted exhaust behaves we should know what good is first.
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| Figure 5 - Pressure during the exhaust stroke at idle should be about 0 psi |
Figure 5 shows a known good engine running at idle. All four strokes of the cylinder are visible in the capture. The red box is calling attention to the pressure in the cylinder during the exhaust stroke. At this point in the four stroke cycle the exhaust valve is open the cylinder is directly connected to the exhaust system. Therefore, the pressure in the cylinder is the same as the pressure in the exhaust. In this case I placed the horizontal cursor at 0 psi and no exhaust backpressure can be seen.
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| Figure 6 - A known good vehicle with a throttle snap should also have near 0 psi during the exhaust stroke |
Figure 6 is the same vehicle as figure 5 when the throttle is snapped. In the capture we can also see 0 psi during the exhaust stroke. This confirms the vehicle does not have an exhaust restriction.
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| Figure 7 - A restricted exhaust will show positive pressure during the exhaust stroke when the throttle is snapped |
Now that we know what known good looks like, let’s take a look at how a restriction behaves. The subject vehicle is a 2006 Buick Rendezvous with a 3.5 liter engine. The customer’s complaint was low power on acceleration. The test drive and VE calculation mentioned earlier in this article (Figure 1 and Figure 2) were performed. Scan data indicated poor VE, rich oxygen sensor readings and relatively normal fuel trim numbers. This was enough to warrant testing exhaust back pressure. Figure 7 is an in-cylinder capture that was obtained when the throttle was snapped in the bay. The labeling of the image is the same as the previous two images. However, I added a second horizontal cursor to measure the pressure in the cylinder. In this case the vehicle was generating in excess of 32 psi on the exhaust stroke. This would be the same measurement we would obtain if we had installed a backpressure gage in the exhaust system. This vehicle had a very restricted exhaust system. Replacing the catalytic converter resolved the issue and restored the vehicle’s acceleration. Access to a spark plug, scope connections and obtaining the capture were extremely quick and easy. I hope this helps illustrate the value of using a pressure transducer and oscilloscope over the older, but still effective, exhaust backpressure testing methods.
Catalyst efficiency side note
I know that catalyst efficiency DTCs do not exactly fit this article, but I wanted to take a moment to address a question that has been asked many times while I have been teaching around the country. The question: Why does a restricted catalyst usually not set a P0420 or P0430? The two most common reasons for this are: the catalyst efficiency monitor is suspended or the enable criteria to run the catalyst monitor have not been met. First, if there is a current misfire, or even a history misfire DTC stored, then the catalyst monitor will be suspended. There is a strong possibility that the misfire was the cause of the catalyst failure to begin with and the PCM will not even attempt to run the monitor in these cases. Second, if a catalyst becomes restricted for whatever reason, the engine load PID (or other possible data) can be out of the range of the enable criteria for the catalyst monitor to run. If this is the case, the vehicle will continue to operate while the converter continues to degrade and the PCM will not execute the monitor and set a catalyst efficiency DTC.
Remember, a catalytic converter can fail in two ways: efficiency or restriction. This article covered the restriction aspect. Efficiency issues require a different logical diagnostic approach.
Summary
When an exhaust restriction is suspected analyze some scan data to back up your theory, choose your physical testing method to prove the restriction, make the repair and perform a repair verification test drive (with a scan tool) to confirm success!
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Advanced diagnostics using the five gas analyzer
The internal combustion engine has been around for over 200 years. In this time, there have been many changes to the engine, the fuel, and the automobile. We attribute the modern engine to Nikolaus Otto. Nikolaus was a German engineer who developed the compression charge internal combustion engine that ran on liquid petroleum gas. Nikolaus’ engineering marvel is still used to power the modern vehicle.
First, some theory
The fuel stock and the internal combustion engine have undergone some changes in the past years, but the basics are still the same. The fuel stock that we will cover is a liquid petroleum product that we refer to as gasoline. Modern gasoline is a mixture of different chemical components with varying vapor points and varying auto-ignition temperatures. Basically when these components are mixed together and form gasoline, they have an approximate flash point of -45°F and an approximate auto-ignition point of 536°F.
It will be necessary to understand that liquid gasoline cannot burn in this state (liquids do not burn). In order to burn gasoline it must be heated so that it makes a phase transition and turns into a vapor (vapors can be burned). The compression within the cylinder accomplishes the heating of the fuel. When air is compressed rapidly the molecules are accelerated off of the moving piston where they hit one another. The kinetic energy from the piston is turned into thermal energy in the air charge. This occurs from the atoms hitting one another which in turn starts the atoms vibrating, causing a heating effect. This process is called Adiabatic Compression. The Adiabatic processes are characterized by zero heat transfer with the surroundings, such as the piston, cylinder and cylinder head. In the case of rapid compression, the process occurs too quickly for any heat transfer to occur to these components. Heat transfer is a slow process. This rapid compression of the air creates a rapid heat increase within the air charge. Thus this heat increase is put into the fuel that is suspended within the air. When this air/fuel charge is heated it turns the fuel into a vapor that can be burned.
Now that the fuel is in a vapor format and is ready to burn, a spark takes place across the sparkplug electrode. The spark ionizes the spark plug electrodes producing a state of plasma which takes the fuel well past the auto-ignition temperature of the fuel; setting up the ignition phase of the fuel. This is where the temperature in a localized area around the sparkplug starts to burn. The next stage is the combustion phase. This is where the charge changes from chemical energy to thermal energy. The heat released is then driven into the next layer of the charge thus igniting it. This is referred to as deflagration. Deflagration is the combustion that propagates at subsonic speeds through the gas that is driven by the transfer of heat. This heat transfer heats the working fluid (nitrogen) which in turn puts pressure on the piston, thus pushing the piston down the cylinder.
Stoichiometry
In the spark ignition method the charge prior to ignition is that of a homogenous charge. This means that the air/fuel charge is evenly mixed throughout the cylinder volume. In order to completely burn an evenly distributed mixture within the cylinder, the air/fuel ratio must be very close to that of stoichiometry. Stoichiometry refers to the weights of the chemicals that will react. In an internal combustion engine the fuel is the reactant and the air is the oxidant. Air is comprised of approximately 78.09 percent nitrogen, which is used as the working fluid, and 20.95 percent oxygen which is used as the oxidant. The reaction will occur between the fuel, which is hydrocarbon based, and the oxidant, which is the oxygen. The stoichiometric ratio between the fuel and air is one where the hydrocarbons and oxygen are at a weight ratio that, once they react with one another, will no longer be present. This means that the hydrocarbons break apart becoming hydrogen and carbon. In the presence of oxygen, the hydrogen combines with the oxygen forming a new chemical; dihydrogen monoxide (H2O water). The carbon attaches to the oxygen forming a new chemical; carbon dioxide (CO2). If the hydrocarbons and oxygen are at a stoichiometric ratio and react with one another then neither of these chemicals will remain present within the combustion gases, see Figure 1. The chemical weight will be the same but the new chemicals formed during a complete reaction will be water and carbon dioxide. Although the mixture is at a stoichiometric ratio, in the real world a complete reaction between all of the chemicals does not occur so there will always be some hydrocarbons and oxygen left after the combustion process. This is due to the flame front being unable to get into the crevasses around the spark plug, valve pockets, and piston rings.
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| Figure 1 |
If the cylinder compression is present, the fuel was vaporized, the air/fuel ratio was that of stoichiometric, the cylinder was homogeneous and the spark occurred correctly, the vast majority of fuel and air will react with one another. When this occurs the tailpipe gas charge will have high CO2 (> 14 percent), low O2 (< 1 percent), low CO (< 1 percent), and low HC (< 100 Parts Per Million (PPM)), as seen in Figure 2.
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| Figure 2 |
Analyzing that comes out
Figure 2 also shows an engine with no problems on start and run. Since the hydrocarbons react with the oxygen then the hydrocarbon level will drop, the oxygen level will start at atmospheric condition at about 21 percent and drop sharply, the carbon dioxide will rise sharply and the carbon monoxide will drop as well. At this point the catalyst (catalytic converter) is not hot enough to further the reaction of the fuel. There will be more on this later.
Carbon monoxide forms when the air/fuel mixture does not have enough oxygen to fully oxidize the carbon. The chemical reaction will always drive to that of carbon dioxide. Note the difference is that carbon dioxide has one carbon atom and two oxygen atoms, where carbon monoxide has one carbon atom and one oxygen atom. If there is oxygen present around the carbon during the combustion process then two oxygen atoms will always stay together and will bond to a single carbon atom. Thus, when CO levels rise this is usually created by a rich condition as seen in Figure 3. CO and CO2 are very good combustion indicators; CO is produced by incomplete combustion where CO2 is produced by complete combustion. Therefore the presence of high CO2 gases of 14 percent to 16 percent represents good combustion has occurred within the cylinders.
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| Figure 3 |
A rich mixture condition is one that has more hydrocarbons than oxygen. When this occurs there is not enough oxygen to oxidize the carbon and hydrocarbons. Thus, there are extra hydrocarbons left after the reaction and each carbon only has one oxygen atom bound to it making carbon monoxide, as seen in Figure 3.
A lean mixture condition is one that has more oxygen than hydrocarbons. When this occurs there is not enough hydrocarbons for the amount of oxygen atoms, so the reaction leaves additional oxygen atoms as well as extra hydrogen, as seen in Figure 3. One may ask: why did the additional oxygen not oxidize the hydrogen during the reaction? This is due to the air/fuel charge not being that of a stoichiometric ratio. In this condition the air/fuel charge has too much space between the hydrocarbons. Therefore as the flame front starts to propagate across the combustion chamber these large areas between the hydrocarbons create impedance to the flame front movement. This in turn slows the flame front allowing only a partial burn of the gasoline. This will leave oxygen, hydrocarbons and hydrogen.
In order to have complete combustion in a spark ignition gasoline based engine the air/fuel charge must be that of a homogeneous charge. A substance is homogeneous if its composition is identical wherever you sample it. This means that the charge mixture (air and fuel) has a uniform composition throughout the cylinder. Additionally the air/fuel charge must be that of a stoichiometric ratio.
A stoichiometric ratio, as discussed above, is where the two reactants that started the reaction are no longer present at the end of the reaction. Different chemicals will have different chemical weights, so these chemical weights will change the stoichiometric ratio. For example, methanol has a stoichiometric ratio of 6.45:1. Ethanol has a stoichiometric ratio of 9:1. Where gasoline, being comprised of various chemical components, has a stoichiometric ratio of 14.5:1 to 14.7:1. If ethanol is blended with the gasoline the stoichiometric ratio will drop depending on how much ethanol is used in the blend.
Lambda and NOx
A reading given for stoichiometry on a gas analyzer is that of Lambda. Lambda is a calculation that is based on all of the gas traces that are read by the exhaust gas analyzer. This equation takes the gases that are coming out the tailpipe and calculates the amount of oxygen and fuel that went in. Make no mistake — what goes in must come out. The weight of the atoms does not change. The molecules are structured differently after the combustion process, however the weight is the same. By taking the exhaust gas weights one can calculate what gases went in. It is extremely important that there are no exhaust leaks in the exhaust system. This allows oxygen to enter into the exhaust system, however this oxygen was not part of the combustion gases. This false oxygen will move the Lambda equation to the lean side when it is not really lean. If there is an exhaust leak Lambda cannot be used.
A Lambda reading of 1.0 is that of a stoichiometric ratio. A Lambda greater than 1 indicates a lean condition. So a Lambda of 1.2 indicates the air/fuel ratio is 20 percent lean of a stoichiometric ratio. A lambda less than one indicates a rich condition. So a Lambda of .8 indicates the air/fuel ratio is 20 percent rich of a stoichiometric ratio.
Nitrogen Oxide (NOx) is a gas that is produced during the combustion process. This is where oxygen bonds to nitrogen. These chemicals do not want to bond with one another so they will stay separated until they are force together. This force will be provided by temperatures greater than 2500°F during the combustion event or extreme pressure conditions during the combustion event.
Applying to drivability
Now that we have set the parameters to combust a gasoline based fuel stock in the cylinder, let’s analysis some data from different engine problems. The first engine problem is a no start condition as seen in Figure 4. The blue cursor at the top of the graph marks the position that all of the gases are measured at. The gases are then read as a digital number on the right hand side of the graph next to the specific gas trace such as; HC, CO, CO2, O2, NOx, and the calculation of Lambda. We will discuss what the gas traces indicate and what is happening within the engine. First we will take note that; the HC is reading 2937 PPM, the CO is reading .025, the CO2 is reading 2.98 percent, the oxygen is reading 16.75 percent, the NOx is reading 140.6 PPM, and the Lambda is at 3.05 percent.
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| Figure 4 |
The HC at 2937 PPM seems like a lot but, when taken with the other gas data, really is not. Since there is CO2 present at 2.98 percent and the oxygen fell from 21 percent to 16.75 percent, we know that some of the hydrocarbons reacted with oxygen. This would indicate that fuel and oxygen are in the cylinder and a spark has occurred. Since the engine is cold the spark is present due to the CO2 reading of 2.98 percent. If there was no spark present then the reaction could not occur, therefore there would not be any production of CO2 gas. The CO is also very low at .025 percent. This indicates that there is more than enough oxygen in the cylinder for the combustion process. The NOx gas at 140.6 PPM also indicates that there was some combustion within the cylinder. The key here is the Lambda reading of 3.05 percent. This indicates that the air/fuel ratio is three times too lean. With a lean air/fuel ratio the flame front is impeded and cannot propagate through the cylinder. So the spark starts the ignition event and creates enough heat for the point of ignition. This then starts the combustion event, however, the combustion event starts but is stopped due to the lean air/fuel ratio. This engine has a lack of gasoline causing the no start problem. This vehicle’s problem was a bad fuel pump.
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| Figure 5 |
Now let’s analyze Figure 5. This is also a no start condition. We will discuss what the gas traces indicate and what is happening within the engine. First, we will take note that; the HC is reading 20200 PPM, the CO is reading .006 percent the CO2 is reading .1619 percent, the oxygen is reading 19.73 percent, the NOx is reading 14.09 PPM, and the Lambda is at 1.14 percent.
The HC reading of 20200 PPM is the correct amount of gasoline to combust within the cylinder. The CO at .006 percent also shows there is not a lack of oxygen within the cylinder. The CO2 at .1619 indicates that there is no, or very little, reaction between the hydrocarbons and the oxygen. The oxygen at 19.73 confirms no, or very little, reaction took place. The lambda at 1.14 percent indicates that the air fuel ratio is 14 percent lean of stoichiometric. However this is a combustible air/fuel mixture. The lack of a reaction is not based on the air/fuel ratio, but on the spark. If there is no spark event to bring the temperature above the auto-ignition point of the gasoline, there will be no reaction between the hydrocarbons (fuel) and the oxidant (oxygen). It is important to understand that if the engine is hot and compression took place then some of the hydrocarbons can react with some of the oxygen without a spark present. However, this will still represent a small amount of CO2. If combustion is established the CO2 will rise sharply. This vehicle’s problem was a bad ignition coil, causing a no spark condition.
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| Figure 6 |
Next, let’s analyze Figure 6. This is a long hard start condition. We will discuss what the gas traces indicate and what is happening within the engine. First we will take note that; the HC is reading 26710 PPM, the CO is reading 3.24 percent, the CO2 is reading 1.164 percent, the oxygen is reading 14.54 percent, the NOx is reading 29.67 PPM, and the Lambda is at .63 percent.
The HC reading of 26710 PPM indicates there is sufficient gasoline within the cylinder. The CO at 3.24 percent indicates that there is a lack of oxygen in the cylinder for the amount of hydrocarbons, additionally a spark has started a reaction to occur. The CO2 at 1.64 percent indicates that a reaction occurred but was incomplete. The oxygen starting at 21 percent and dropping to 14.54 percent indicates a reaction took place with the carbon producing high CO gas traces and low CO2 gas traces. The NOx at 29.67 indicates that combustion occurred. The Lambda at .63 indicates the air/fuel mixture is 37 percent rich of stoichiometric. The air/fuel mixture at the beginning of the starting process is too rich for the starting conditions of the engine. Thus a long hard start condition is present. This vehicles problem was a misreading Engine Coolant Temperature (ECT) sensor which allowed the cold start enrichment to be active, thus creating a rich start condition.
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| Figure 7 |
On to Figure 7. This is a hard start condition with poor engine running. We will discuss what the gas traces indicate and what is happening within the engine. First we will take note that; the HC is reading 7198 PPM, the CO is reading 7.159 percent, the CO2 is reading 5.063 percent, the oxygen is reading 8.199 percent the NOx is reading 217.6 PPM, and the Lambda is at .89 percent .
The HC reading of 7163 PPM indicates that the hydrocarbons are not burning completely. The CO at 7.159 percent indicates a poor combustion process, but indicates that a spark event occurred. The CO2 at 5.063 percent confirms poor combustion of the gasoline. The oxygen starting at 21 percent and falling to only 8.199 percent shows that the combustion event happened but is incomplete. There are leftover hydrocarbons and leftover oxygen that should have been combusted in the reaction. The NOx is at 217.6 showing a reaction occurred. The Lambda at .89 percent is 11 percent rich of stoichiometric. However this should be a combustible mixture that is just slightly rich. This is caused by either a weak spark or the ignition timing is off. This vehicle’s problem is a late ignition timing event.
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| Figure 8 |
Figure 8 is a rough running idle condition. We will discuss what the gas traces indicate and what is happening within the engine. First we will take note that; the HC is reading 1663 PPM, the CO is reading 2.27 percent, the CO2 is reading 12.52 percent, the oxygen is reading 2.71 percent, the NOx is reading 13.2 PPM, and the Lambda is at .99 percent.
The HC reading of 1663 PPM indicates that the hydrocarbons are not burning correctly. The CO at 2.27 percent indicates that there is poor combustion within the cylinders, but a spark event did occur. The CO2 at 12.53 is a little low indicating that the combustion is poor. The oxygen at 2.71 percent is a little high indicating that the combustion event is incomplete. The NOx is quite low at 13.2 PPM. The Lambda is .99 percent, indicating that the engine is running at a stoichiometric ratio. Since the air/fuel ratio is correct at a Lambda of 1 the air/fuel charge is definitely combustible. However the combustion event is incomplete. Additionally, just off idle the combustion gases are good. So the problem occurs just at idle. This vehicle’s problem is the Exhaust Gas Recirculation (EGR) valve is intermediately sticking open at cruise and when it returns to idle dilutes the air/fuel charge. This puts too much space between the hydrocarbons creating an impediment to the flame front and, thus, incomplete combustion.
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| Figure 9 |
Now let’s analyze Figure 9, a vehicle with a DTC P0420 (Catalytic Converter Efficiency). We will discuss what the gas traces indicate and what is happening within the engine. First we will take note that the HC is reading 166 PPM, the CO is reading 1.26 percent, the CO2 is reading 13.81 percent, the oxygen is reading .426 percent, the NOx is reading 1183 PPM, and the Lambda is at .979 percent.
The HC reading of 166 PPM indicates that the hydrocarbons are slightly high. The CO at 2.27 percent indicates that there is poor combustion within the cylinders, but a spark event did occur. The CO2 at 13.81 is a little low indicating that the combustion is incomplete. The oxygen at 2.71 percent is slightly high indicating that the combustion event is not complete. The NOx is quite high at 1183 PPM. The Lambda is .979 percent indicating that the engine is running 2 percent rich of a stoichiometric. Since the air/fuel ratio is correct at a Lambda of close to 1 the air/fuel charge is definitely combustible, however, the combustion event seems incomplete. This exhaust gas data was taken while driving under load. These exhaust gas traces are correct for the condition that they were under. The problem is that the catalytic converter is not functioning properly and can no longer react the exhaust gases, further combusting these gases.
The catalytic converter is a device that further combusts the exhaust gases through catalysis. This is where heated metals drive a chemical reaction to a different chemical species. All metals will drive catalysis, but the chemical species at the end will vary depending on which metal was used. Automotive three-way catalytic converters use platinum, palladium, and rhodium. These rare earth metals are used because they drive the catalysis to a desired chemical species. These metals will need to be hotter than 700°F in order to function correctly. This means on cold start the catalytic converter is not working for the first 20 seconds to one minute. Once the catalytic converter has obtained operational temperature it will further combust the exhaust gas through catalysis. So any exhaust gas analysis must take this into account. For example, if the engine is misfiring one would expect to see incomplete combustion gases at the tailpipe such as high HC readings with high oxygen readings. However the modern catalytic converter, when at operating temperature, can continue to combust the gases where there are no signs of incomplete combustion.
It is clear that the exhaust gases can be used for advanced engine diagnostics. We have seen just a few examples presented in this text. Be aware that you can use these gases to do far more than what has been presented in this article. With a little knowledge and a little practice you will be diagnosing engine problems that use to take hours, in just minutes.
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