Cummins ISX CM871 Technical discussion

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Rawze, Aug 13, 2013.

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  1. Rawze

    Rawze Medium Load Member

    Jun 29, 2013
    I am creating this thread so that those who know, own, and/or repair this particular engine can learn from each other. I have one of these engines in my truck and know much of its secrets. I have helped many, many people solve the elusive EGR, DPF, fuel mileage, and other problems that regularly plague this engine, and have learned much in return. So far, most of the problems I have seen O/o's have with this engine, stem from neglect of key components that need regular attention, so I will open this thread with a list of what I have found that should, by now, be considered common knowledge. First tho, I would like to share my personal opinion of this engine. When comparing it to other brands of similar age/style, I think that for the one-truck O/o, among these newer Post EGR/DPF egines, the CM871 is the easiest, least expensive engine to keep healthy with its EGR/DPF intact, while maintaining decent fuel mileage long term. There are many who will disagree, because there have been way too many unnecessary bad experiences by drivers and truck owners that speak otherwise. Hopefully, this thread will put a stop to some of this through shared experience and education, allowing us O/o's out here to keep more of our hard earned cash, rather than giving it to the now, way-overpriced dealers and engine shops that are all too eager to blame a turbo or other major component, when most often, its likely to be a dirty sensor or a pipe that has gotten clogged with soot. This bothers me greatly, because I think things like this have happened so often, that it has now become common knowledge to just assume the turbo's/dpf's/egr valves on this engine are just bad/junk, and are the likely cause, when in fact, very often they are not. I am not here to post about how great this engine is by any means, sure it has its flaws, like any other engine, but it definitely is not as bad as most would have you think. One of the biggest downsides I think, as a truck owner with one of these engines, is the fact that this engine likes to be worked on at least every 200-250k miles or so, to keep it healthy, especially if the EGR/DPF is in tact and operating. Why is this a downside?,...Many truck owners these days are NOT mechanically inclined at all, nor do they have the wish to become so. For these type of truck owners, this is definitely an expensive engine, because they will typically run to the nearest dealer/shop whenever something is not quite right. This, very often, lands them in an endless loop of problems that seem to have no end, where the shop will milk their wallets dry, throwing major components at the truck repeatedly.
    Truck owners who do this, after spending many thousands on what are typically 'ghost problems', will usually hate the engine and its egr/dpf systems, blaming their lemon truck, rather than taking the extra step to educate themselves on how to keep that truck out of the shop. Other O/o's, after having problems, will try to learn about these systems and their trucks to reduce shop-time, often are guided by those same shops that are milking them dry, where it ends up doing little to help them as a result. What you end up with, is a bunch of bad information, half truths, and a general flood of mis-information based on people's opinion. This is why I chose to specifically talk about a single model engine here instead of trying to cover all of one brand, because the wider the paintbrush used, the more blurred the image becomes.

    What should be Common knowledge of the EGR/DPF system on this engine (this, i have posted before, just putting it here to start the thread)...

    These are the steps (An EGR Tune-up) to perform every 200-250k miles on the CM871 ISX engine to prevent or stop some well known symptoms that will usually include one or more, but not all of the following symptoms...

    Reduced fuel mileage
    Lack of power
    Sluggish throttle response
    Little or no acceleration for several seconds
    Surging or power increases above 1400-1500 RPM.
    Rough idle / fluctuating idle

    Frequent Regen lights / alarms
    Frequent Regens / parked Regens
    DPF faceplug alarms
    DPF Inlet temperature alarms

    Slight oil pressure drop after only 15-20k miles after oil has been changed (clogging filters).
    High amounts of soot in the oil
    Crank case filters clogging too often

    Turbo hesitaion/lag
    Turbo coughing
    Turbo Actuator Alarms
    Turbo overspin
    Charge Pressure faults
    Turbo inlet temperature alarms

    EGR actuator alarms
    Delta-P alarms

    Here is some info along with what I usually recomend someone do to their truck concerning only an egr tune-up, asuming this has never bee done on thier truck, and there aren't more obvious problems like a bad CAC,etc. Its a re-post on what to do to a used truck after purchasing it...

    <> EGR cooler, Visual: Looking to see if it has ever been replaced. Replacements are typically silver in color, or show signs of being re-painted. If it HAS been replaced, this is a good sign. Failure rates on these are high during the truck's first 180-200k milage range, where the warranty will still cover it. They fail due to settling of the block during the engine break-in period, causing mechanical stress to the unit. Cummins Engineering, when I asked about this in 2010, informed me that it was an 80% failure rate, and that they did studies on loosening/re-tigtening the bolts to relieve stress with little results. Replacement is more effective. After that first failure, re-occurrences are not common unless the engine suffers conditions that cause the block to 'settle' again, like say changing its governed speed by a large amount and driving it hard at the new speed. Regardless, keep a close eye on coolant levels, marking the tank at a given known coolant temperature. A leaky EGR cooler will shorten the life of just about everything on the engine very quickly. White smoke from the exhaust and coolant loss are typical of a bad EGR cooler. It will also cause carbon and soot to cache up in the intake manafold, lowly choking the engine.

    <> DPF, Visual: Look for signs to see if it has been removed/replaced. If it HAS, this is a red flag. The DPF on a cummins is big enough to sustain a healthy exhaust flow for about 700k+ miles, where ASH, not soot or coolant, will finally cause it to read above 3.0hpa on a constant basis (above 3.0 costs fuel mileage). The only exception to this is if it gets cracked/damaged due to excess road stress or being impacted by road debris (not very common but can happen). Why then is it so common for it to fail or be replaced/cleaned before this mileage range?,...Outside problems, #1 being the after-treatment injector going bad, then second, a poorly running engine that produces a lot of excess soot, or a bad EGR cooler plugging it up with coolant. ALL of witch can be avoided, with good maintenence practices, long before it kills the DOC/DPF. If it has been replaced or cleaned at 380K miles or less, then it is highly likely there were, and are still problems with the engine/EGR system. Removing the DOC/DPF should only be a LAST-RESORT type item when everything else has been done to avoid it, and it is the only thing left, after replacing the injector/sensors with a new ones and force-regening it to determine its actual hpa.

    <>Determine/Remove the soot buildup in the EGR system: Remove the IMAP sensor from the intake manifold. Very easy to do, takes less than a minute. If it is buried in soot, and it will be, at 250k+ miles, it is, at the very least, costing you fuel mileage by now, or at its worst, causing turbo problems, power loss, hesitation in the acelerator, and/or excess soot problems. You will get turbo actuator alarms long before you get alarms for this sensor being cloged. Many mechanics are fooled by this, chasing ghost problems in the much more expensive components like the turbo, egr valve, etc. I have the Insite/ Fault tree software. On its best dsays, it is only about 30% acurate in dealing with these type of ptroblems. The IMAP sensor, most of the time, can siply be cleaned using a dry toothbrush and NO chemicals. This one sensor has actually put many O/o's out of buisness. I have witnessed trucks go from 4-mpg to 8-mpg, just from cleaning it.
    Assuming it was in fact covered in soot, you will need several cans of 'Carb and Choke' cleaner. NOT 'Brake cleaner'!!!. Brake cleaner turns everything into a soot magnet. You will have to remove the intake manifold, Venturi (egr mixer) pipe, and Delta-P crossover tubes, washing them out, to bring back the engine's full fuel mileage potential and New-running glory. The Delta-P (EGR Differential Pressure Sensor), if it is the origional from the factory (painted red), it will have to be replaced. It cannot be cleaned properly without it giving false readings afterards. As this sensor clogs up, it causes EGR valve and EGR actuator alarms and problems, power loss, fuel mileage loss, and 'turbo-coughig' problems, quite often without ever throwing a code for the sensor.

    <>Clean/Replace Exhaust Manifold Backpressure sensor: This sensor usually lasts 400-600+k miles before giving problems. It can usually be just simply cleaned, along with its feeder tube, comming off the exhaust manifold. If it is going bad, the turbo will act up. Symptoms can be of,...Turbo-coughing, turbo-lag, actuator alarms, turbo overspin alarms, and/or even turbo inlet temperature alarms. This sensor can actually kill a turbocharger over time, and/or can cause a cracked head or gaskets from excess head pressures generted by the turbo acting up. This sensor can be cheked with Insite to see if is reading correctly if it is in question, but its a cheap sensor, so just replace it if its suspect.

    <> The After-treatment injector (doser injector): It operates similar to a spray-can nozzle and is located at the turbo exhaust outlet. It is easy to inspect by simply removng the 2 exhaust clamps on either side of it and looking down into the pipe. They start clogging up at 250k+ miles like clockwork, even on engines that run well and have never been idled, causing many DPF and Regen problems when they do. They are easy to change, but only if your willing to drain your coolant into some buckets first (that kinda sucks). Yes it can be cleaned, and that helps the DPF a lot, but NO, most of the time, after cleaning it, will it last very long afterwards. It also costs you fuel and can leak coolant directly into your DPF as they go bad or fail. Not worth the risk of cleaning it if u ask me. The doser injector is also a money-maker for most of the dealers. They will almost always go straight for the DOC/DPF when you visit them, ignoring the injector because of the all-to-typical 'DOC/DPF Face-Pluged alarm' that is thrown by the engine, when there is little or nothing much wrong. The engine likes to throw this code waay too aesily, and many O/o's fall victim to it when they visit the repair shop, many times, repeatedly, before the actual, more minor problem is found.

    To sum all this up,...

    every 250-300k miles,...
    Remove and clean the IMAP sensor, Intake manifold, Venturi pipe, Delta-P crossover tubes, Exh. backpressure sensor and feeder tube, and EGR temp. sensor.

    Just replace the Delta-P sensor and After-Treatment injector. Then perform a DPF 'Forced Regen', ensuring the DPF is still below 3.0 hpa (it will almost always be below 2.0 hpa after a good cleaning by the regen with new after-treatment injector).

    cost?,...$300-400 for after-treatment inj., $150-200 for Delta-P, 3 five-gallon buckets for holding your coolant, and a day of downtime, while drinking beer and getting very dirty. If you can change a spark plug for your car or lawn mower, then you are very likely capable of these things as well.

    Can a shop do this for you?,...well,...possibly for a few thousand bucks. Not worth taking it to them if u ask me.

    Ignoring it,...Countless truck problems, downtime, and thousands uppon thousands in repair bills by the truck steeler(dealer) because they will blame the bigger ticket items either out of ignorance, or for extra profit. Most will laugh at you for mentioning simply cleaning these things instead of replacing them.

    Maybe this helps someone out there who is already having issues,...Rawze.
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  3. JPenn

    JPenn Road Train Member

    Mar 5, 2008
    Southern Tier NY
    Excellent info. Anyone who's got one of these engines, you owe this guy a beer. We've got a fleet full of them in oilfield service where they're idled or running the PTO constantly, and the 2 biggest things we hit (aside from an obnoxious appetite for EGR coolers, I swear Cummins makes them to fail after X hours) are the IMAP and Delta-P sensors causing trouble.
  4. Rawze

    Rawze Medium Load Member

    Jun 29, 2013
    I would like to also share in the thread, the chapter in the book I wrote called 'The First Time Class-8 Lease-Purchase Owner-Op Guide' for those who read these forums that are trying to learn about EGR, as drivers and/or truck owners. Most of it was in fact written around the CM871, but applies to other engines as well. Here it is...

    Understanding Your EGR and DPF as a Truck Owner

    If you have a truck that is newer than 2004, then the engine is most likely to be an EGR engine. Exhaust Gas Recirculation (EGR) is a fancy technical term used to describe the fact that some of the engine exhaust gas is returned back into the intake. To put this into perspective along with its effects, lets imagine for a moment that you are an athlete well trained in running marathons. One day, the California Resources Board (CARB) and the EPA decide they no longer like marathon runners because they breathe up too much oxygen and fart too much during races. To stop them from using up all the oxygen, they decide to make a law limiting the amount of fresh air all younger athletes are allowed to breathe. Now, for all new athletes, when they are in California, they must breathe through a paper bag with a small hole in the end of it at all times. Breathing through a paper bag with a tiny hole, definitely limits your oxygen intake, and trying to run a marathon like that will seriously slow you down, hopefully making you fart less as well. EGR to a diesel engine is what the 'Paper Bag' is to the athlete. It limits the amount of oxygen to the engine by starving it of clean air, making it re-breathe already used up air from the exhaust. The result is that the fuel cannot burn as hot, making it produce less harmful exhaust gases.

    Now that you know what EGR actually does, why would it be so important for an owner-op to know about it, its parts, and its technical details? Isn't that what a mechanic is for? Theoretically yes, that is what a mechanic is for, and theoretically yes, they are supposed to fully understand these systems and their effects, but realistically, when your truck ends up in a repair shop over these kinds of problems, the mechanic is only there to solve the problem that got you there, getting your truck back on the road.

    If you are very lucky, the mechanic will find the problem and correct it, but most of the time, what happens is that the truck ends up in the shop over and over, costing you thousands and thousands in repair bills, and thousands upon thousands in lost pay from all the downtime. The only way to prevent this is to either get really lucky and not have any problems (possible but highly unlikely), or to take a proactive stand to prevent it. This guide is not written to help you rely on luck. It is written to help you hang onto every last red cent that you work so hard for, instead of giving it away to some overpriced, under-qualified, repair shop unable to care about helping you be successful in what you do.

    The sad thing is that most shops do actually care, but either don't know how, don't have time, don't get paid enough for, and/or are just too expensive to take that extra effort. I highly recommend that you get directly involved, even if you have someone else do the work for you. The ideal thing to do, is learn how to do the easier things yourself, saving you literally thousands. Only pay someone to do the things that you cannot do yourself when it comes to repairs, or component replacement. The key to all of this, especially if you will need a shop to perform any EGR or DPF related work for you, is to know enough to be able to direct them toward finding and solving the actual problem(s). Also, you need to know enough to direct them toward continuing past the problem, performing relevant maintenance, so that repeat visits are prevented.

    Everyone benefits from shared knowledge, so if you do find yourself in a shop, getting repairs or service work done, EGR or not, knowing enough to oversee and discuss what the shop has to do for you will always have a huge impact on how well things go. After all, YOU ARE PAYING THEM, not the other way around.

    The purpose of EGR itself, no matter what type or brand of diesel engine, is there to make the fuel burn at sort of a 'sweet spot' temperature to minimize harmful exhaust gases, while still providing as much energy as possible. The exhaust gas temperature (EGT) should be 570 degrees Fahrenheit give or take about 50 degrees when this is happening. The Engine's computer (ECM) monitors the exhaust via a temp. sensor, making changes, opening or closing a valve that controls how much exhaust gas is sent back around to the intake. This valve is called the EGR valve.

    When the EGR valve is closed all the way, the engine will run on pure clean air provided by the turbo, and when it is open all the way, the engine will be re-breathing, depending on your engine, up to about 40% of exhaust instead of clean air. This mixture of clean and dirty air needs to be pretty accurate for your truck to get good fuel economy, so if something isn't operating quite right, then your wallet is the first thing to suffer, long before any actual faults occur. To sum it up, your EGR valve controls the dirty air, and your turbo controls the clean air going into your engine. If either system is leaking, restricted, or otherwise not working properly, fuel economy goes down, and if it gets bad enough, it could shut you down with a fault.

    Starting with the clean air side of things, clean air is sucked in through the engine air filter, then gets pressurized up to 30+ PSI by the turbo, where it also gets very hot and expands due to the heat. That pressurized, hot, expanded air is then sent through the air radiator (called a charge air cooler), cooling it off again, making it less expanded, then onward past the EGR mixing tube, where it mixes with dirty air, then into the engine.

    The ECM precisely controls this clean air system by altering the speed of the turbo, changing the air pressure. The air pressure itself is determined by several sensors that the ECM monitors. Some engines have more sensors than others, so I will just include them all. To pre-determine the oxygen content of the air, the ECM needs to know the current altitude, humidity, and temperature. This mini 3-sensor weather station can tell if you are on the beach, or if you are climbing Veil Pass. After all, the air is pretty thin at 12,000 feet. There is another temp sensor, just to verify that the 'weather station' is accurate mounted right at the turbo intake pipe.

    All those sensors are just to tell the ECM what the air quality is. From there, the ECM keeps an eye on the turbo itself through the use of a speed sensor (mounted on the turbo, having a slightly-thick green wire), just to make sure the turbo doesn't spin too fast.

    The ECM also uses 2 sensors mounted right where the air goes into the engine on the intake manifold, after the clean/dirty mixer pipe. They are air pressure, and temperature. These 2 are the most important for determining the correct pressure, and the rest are just compensation for climbing hills to help fuel economy slightly.

    The air sensor on the intake manifold is referred to as the 'IMAP sensor' or 'Intake Manifold Pressure Sensor'. This sensor is in the path of both the clean and dirty air exposing it to soot on a constant basis. It is going to get dirty, start reading incorrectly, and will eventually fail, even on trucks that never idle, were soot problems are less. It is very easy to remove and clean (or replace if needed), so I recommend that you learn to do it yourself. I have seen service shops rebuild and/or replace entire turbo's, spending thousands of dollars, trying to fix turbo-related fuel economy problems, never solving them, all because that sensor, along with others, are simply dirty.

    If you are ever faced with EGR related problems (Not DPF problems), where the turbo starts to act up as well, this could be a clean air related issue, but since the ECM relies on both clean and dirty air system to operate correctly, both should be looked at. Preventative maintenance to both these systems will almost always prevent major shutdown issues, so if you find, suddenly you are faced with one related directly to EGR, and you have to shut the truck down anyways, just go through both the entire systems as throughly as possible. If you are not afraid to get dirty (and you shouldn't be if you want to be profitable), then start by getting the engine codes if possible to verify it is in fact EGR related. Most trucks have a way to display fault codes in some form or another, so make some phone calls or look on the Internet on how to do this. It usually involves turning the ignition switch and holding some buttons, writing down flash codes, then looking them up in some manual or reference guide.

    Call a repair shop familiar with your model truck, and verify your codes, getting some basic opinion as well. Turbo actuator, turbo speed, and/or intake sensor errors are definitely clean air related. No matter what kind of EGR codes you get, the first thing you want to do is go through the basics as much as possible before resorting to putting it in a shop. This saves you a lot of money and reduces the possibilities of the problem greatly. Next, if you have to go to a shop, have the them perform the things you cannot do yourself as either a start, or as an addition to what needs to be done. Remember, you are paying them, make them work for their money in a way that ensures you get the most bang out of your dollars spent, so that your overall profitability, and fuel economy stays as high as possible.

    To troubleshoot and/or PM the clean air side of the system, start by doing the obvious. Replace the air cleaner for the engine if it is old, and check the piping between it, and the turbo for any cracks, gaps, and loose clamps or boots. If the engine will run at all, use a soapy water spray on all the intake piping, the turbo, the EGR piping, etc. looking for leaks while the truck is running. This helps eliminate the obvious like worn charge air cooler boots, and loose pipe connections.

    The next thing you can do, if you can do it yourself, will cost you no money, is to remove the EGR mixing pipe and ensure it is not partially clogged with soot. As soot builds up in this pipe, your fuel economy indirectly goes down. The ECM will try to overcome this restriction by increasing exhaust back-pressure using the turbo. It is fairly easy to remove on most trucks, so doing this yourself will save you a lot of money. Removing the boot coming from the charge air cooler and looking down into it will fool you because it will look clean. You usually have to remove the whole thing to actually see the soot inside it. If it is dirty with soot, then just clean it out with a dry brush, like a tooth brush or a brush for cleaning cups when you wash dishes. Chemicals or sprays should be avoided, because they will usually turn this pipe into a soot magnet afterwards. Next cheapest thing is to just go ahead and pull and replace the the 'Intake Manifold Pressure Sensor', keeping the old one. It is dirt cheap compared to the other parts of the clean air system and a hundred bucks later, you will not only eliminate it from the equation, but ensure it is not costing you fuel economy from incorrect readings. If replacing it does nothing, clean up the old one using a dry toothbrish, and keep is as a spare for testing.

    Really, the only thing left in the clean air side of things is the charge air cooler, and the turbo itself. If it has been more than 200k miles since the charge air cooler has been tested, while the truck is down, definitely test it for leaks actually determining its 'leak rate', instead of just doing a pass/fail test. The leak rate should not be worse than 15 PSI of loss in two minutes. If it is, then it is costing you fuel economy, and if it is really bad, then it is a good bet that it was the initial cause of your EGR problems, but I wouldn't stop there.

    The turbo can sometimes has actuator or bearing problems itself, but it can also have a seal problem that causes the clean air side of things to have lower than normal pressure, causing fuel economy loss, and/or occasional crank case pressure faults. This seal problem can be tested by doing a crank case pressure test. Excess crank case pressure in the engine is usually only caused by 2 things, a faulty turbo with bad seals, or excess cylinder wear. Too much crank case pressure from excess cylinder wear is always couped with how much oil your engine consumes. If you have high oil consumption, like say you have to put in a gallon of oil every 6 or 8 thousand miles, then it is probably not the turbo, but if you get high crank case pressure, and no oil consumption, the turbo is a good place to point your finger. That pretty much sums up what can be done to ensure the clean air side of your engine is able to operate properly, so the next thing related to EGR is to look at the dirty air side of the system.

    The Dirty air side of the system, otherwise known as the EGR system, is a system that will always require some routine maintenance if you want to keep your truck at its highest fuel efficiency and ensure it does not have EGR problems. It is a good idea to understand this side of the system well, so that you can keep an eye on, and prevent problems before they shut you down.

    As the engine runs and produces exhaust, the exhaust flows from the engine block through the exhaust manifold, then branches off into two directions. Most of the exhaust flows into the back of the turbo, keeping it spinning, then out, past a short section of pipe where the dosing (after-treatment) injector is located, then down to your DPF. If your truck has no DPF, then there will be no after-treatment injector, or DPF, but instead, an actual muffler. From there it goes out to the stack. Back at the exhaust manifold, where the exhaust goes two directions, the gas that isn't flowing into the back of the turbo, passes through several EGR components.

    Which device it passes through first, second etc. may be different on different trucks, but they all have the same basic components. The exhaust gas is 570 degrees plus, and is too hot to send back into the intake of the engine, so it is pushed through a small radiator called the EGR cooler to cool it off to about 200 degrees Fahrenheit. After that, it passes through the EGR valve, so that the ECM can control how much gets sent to the intake. After the EGR valve, it passes through a pipe that goes around the engine back to the intake, and along this pipe are 2 sensors. One is a temperature sensor, letting the ECM know that the gas isn't too hot for the intake, and the other is a sensor that detects how fast the gas is moving through the pipe. That sensor is called the 'EGR differential Pressure Sensor'. This sensor is what the ECM uses to control the EGR valve to help get the desired clean to dirty air mixture. From there, the gas flows into the EGR mixing pipe, then the mixed clean and dirty air that goes into the engine.

    The 'Dirty Air' (EGR) side of the system is just that. It is very hot and contains soot, possibly coolant, already burnt fuel, soot, carbon dioxide, soot, NOX gases, and more soot. Soot is the killer of the entire EGR and intake system. Second to that is the possibility of coolant. Yes, coolant. Those hot gases are cooled off by the EGR cooler, which uses coolant from the radiator to do its job. If there is any kind of leak in the EGR cooler, then coolant ends up in the dirty air system clogging and sticking to everything, gumming it up and making it a soot magnet. Coolant also ends up in your cylinders where it gets pushed past the piston rings getting it into your oil, destroying the oil's ability to lubricate your engine. An EGR cooler leak can destroy a lot of components fast, and can cause really big problems with every single exhaust related component including the turbo, all the sensors, the EGR valve, and the DPF.

    The signs of an EGR cooler leak are white smoke out the stack, a drop in coolant level where you can find no leaks, and/or failing a radiator pressure test where there is no leaks found. If the leak is small, then you can use 'Valvoline ZEREX Super Sealer for HD Applications ' to stop it, and is actually recommended by the engine makers for EGR cooler leaks. Using the super sealer is ok as long as you keep a close eye on your coolant levels to make sure it actually stopped the leak. If it is a bad leak (you are going through a gallon or more of coolant in a month), then get it fixed right away. That much coolant can kill your DPF, EGR valve, or turbo very quickly. A total EGR cooler failure with a massive leak can actually hydra-lock your engine, so if your EGR cooler starts leaking, Personally, I would just replace it.

    Soot is the slow silent killer of EGR system components. No matter how you drive your truck, soot will build up in all the EGR components making them operate incorrectly, eventually causing them to fail. Idling an EGR truck can accelerate this process greatly, so if you have to idle a lot, consider getting an APU.

    Isn't the DPF supposed to take care of the soot? Can't I just do a Parked Regen to fix it? NO, you cannot do a Parked Regen to fix your soot problems, because NO, the DPF does not filter the exhaust sent to your EGR system. The act of mixing clean air with dirty air itself produces soot. That soot is carried by the exhaust gases from your exhaust manifold directly into your EGR cooler, EGR valve, Differential Pressure Sensor, Mixing Pipe, the Intake Manifold Pressure Sensor, and the cylinders. It deposits slowly over time, clogging them up, causing delayed readings, and eventually false readings and/or a stuck EGR valve. How fast this happens is relevant to the year of your truck, how much you idle your truck, how healthy the engine and intake system itself is, and how hard you try to push your truck up hills in the wrong gear. For most 2005 – 2008 trucks, the symptoms of soot related problems usually start at around 450+k miles. On 2009 - 2011 engines that do not use Diesel Exhaust Fluid, the symptoms usually start showing up at around 250-300k miles because they use more EGR than previous year model trucks, because of newer emission standards.

    How does an EGR cooler get damaged and start leaking coolant? Well actually the EGR cooler itself has no moving parts. This means there is nothing to wear out, so how does it break? By excess coolant pressure, corrosion from the coolant itself, or mechanical stress. Excess coolant pressure can damage it easily. If your radiator pressure cap goes bad, and it allows too much pressure to build up in the radiator, then very easily, it can crack the EGR cooler causing it to fail. A pressure cap is ten bucks, so I recommend just replacing it at the first sign of an EGR cooler failure, or if the EGR cooler actually gets replaced, just as a safety measure. Corrosion from the coolant is less likely, but possible. Regular testing of the PH balance of the coolant will usually catch this long before damage is done. A radiator flush and the coolant replaced at 400 – 500k miles is not just a suggestion, but very important to help keep the corrosive properties down. Lastly, and usually the most likely cause of an EGR cooler failure is mechanical stress. Some coolers are pretty delicate in their design, so excess stress can kill one fast. Excess stress can come from several sources, so all must be looked at when replacing a cooler. Excess vibration from the crank shaft damper is one source. They start to go bad at roughly 500k miles, so there again, preventative maintenance can stop this from being the source.

    Any time the coolant or engine overheats, it can cause excess stress in the form of rapid expansion to the cooler. This can come from actual overheating issues, or also from simply turning the engine off before letting the heat settle down after a long hill climb, as discussed in the chapter 'Anti-Idling Methods and APU's'. If your EGR cooler is mounted directly to the engine block (most are), then any stress to the engine block itself, like rapid heating or cooling can cause the EGR cooler to crack under stress as well. The exhaust side of diesel engine blocks actually warp and distort slightly, settling over time. Most of this settling happens within the first 200k miles of the engine's life, but can happen again if the trucks operation is changed drastically. One example of this is a truck that has had its first 200+k miles spent governed at 63 mph, then suddenly it gets changed to 75 mph. The extra strain the engine is put through after suddenly changing its speed can, in fact, cause the engine components, including the block to have to 'settle' again. The engine is made of metal, not stone. Things settle, warp, and distort over time. The best way to avoid EGR cooler problems related to stress, is just simply to drive the truck in a reasonable manner, rather that to push it to its limits all the time.

    Why do EGR valves fail? Heat and/or soot mostly, but they can also fail from road salt intrusion. On many of the earlier EGR engines, and even on a few new ones, the exhaust gas from the manifold is sent into the EGR valve before it is cooled by the EGR cooler. This means that the EGR valve suffers the full 570+ degree heat from the exhaust. Poor design if you ask me, but I am not an engine maker. The engines where the heat is this high going into the EGR valve, generally suffer regular EGR valve failure problems, especially if they are driven hard. If you have one of these engines where the EGR valve is BEFORE the EGR cooler, then at first sign of EGR problems, have this valve re-tested, removed and cleaned, and/or replaced. The lifespan is usually about 200-400k miles. Secondly, on engines where the EGR valve is AFTER the EGR cooler, the exhaust gas temperature is only about 200 degrees or so. The biggest killer for EGR valves of this type of setup is actually soot and/or road salt intrusion. Soot will build up in the valve, eventually clogging it and making it stick. The problems with clogging and sticking are usually problems that produce no fault codes for the engine, unless they become very bad. What happens long before the fault codes, is that you get fuel economy loss, and/or turbo actuator problems. The turbo actuator problems are usually a ghost of the real problem, which is improper clean/dirty air mixture. Also, the turbo may get a symptom known as 'Turbo Coughing', where the turbo hesitates or spins up erratically. EGR valves that are sticky, can usually be cleaned instead of replaced, if done properly. Using chemicals to clean them is not a good idea, so a dry toothbrush, there again can solve some otherwise, pretty expensive problems. If you are unsure of your EGR and/or turbo problems, I recommend doing things from the cheapest and easiest, working toward the more expensive. The EGR differential pressure sensor, and the EGR mixing tube are going to get just as dirty, so start there. Replace the EGR differential pressure sensor and clean the EGR mixing pipe, and the EGR temperature sensor before even considering replacing the EGR valve. The next step is to clean the EGR valve to see if the problem changes or goes away. Replacing the EGR valve should only be done if it is actually the only thing left to blame for problems in the dirty side of the system (keeping in mind the clean air side). They are usually $800+ dollars or more to completely replace.

    So how can you prevent and/or predict EGR related failures? By performing preventative maintenance on the EGR components. Unfortunately, since no one wants to be bothered by pulling parts off your engine just to clean them, most will argue that you shouldn't bother until you get an actual problem. It is those same 'Most' that end up in the shop with several thousands in lost profit by being down and paying a shop to maybe, if they are lucky, find the problem. Learn to remove and clean the EGR and Clean air sensors, learn to remove, clean, and re-install your EGR valve. Learn how to replace the After-treatment injector yourself. Learn to remove and clean your EGR mixing pipe. All of these things combined, can be done in a few hours saving you literally thousands in prevented downtime and repair costs. Take your truck to a repair shop for things like an EGR cooler leak or turbo failure, Not for the minor things you can do yourself, especially if those things have to be done regularly. To put it all together, based on experience helping many truck owners improving their fuel economy and/or solving EGR problems that the shops just couldn't fix, you should perform what I call an 'EGR Tuneup' at regular intervals (every 250k miles), or if you start to see the symptoms of an EGR problem. This 'EGR Tuneup' should consist of the following...

    Remove, Clean, and Inspect These Components...
    Intake Manifold Pressure Sensor.
    Intake Manifold Temperature Sensor.
    Gas Recirculation Temperature Sensor (EGR temperature sensor).
    Exhaust Manifold Back Pressure Sensor.
    EGR Valve.
    EGR Mixing Pipe (Venturi Pipe).

    Perform These Tests...
    A coolant pressure test, checking for EGR cooler leaks.
    An oil analysis checking for excess soot and coolant intrusion.
    Charge Air Cooler Leak Test.

    Intake, Exhaust, and EGR Piping Leak Test (spray joints with soapy water during idling while pipes are not yet hot).
    Check turbo actuator for correct travel distance.
    Remove the exhaust pipe from front of the DPF, rev the engine, and check for excess soot from the engine during high idle and/or acceleration.
    A forced Regen verifying the temperatures and hpa readings.

    Replace These Components...
    EGR Differential Pressure Sensor.
    Clean or Replace the After-treatment Injector (If you have a DPF).

    What about the possibilities of removing or disabling the EGR? Well, it is illegal, and the EPA and/or CARB can fine you or shut you down. At some point, just like on cars, emission testing will get popular, as it will become another means of collecting money from the trucking industry. Keeping that in mind, the answer is Yes, but with possible consequences. Disabling your EGR on the newer engines can be done in 2 ways. Each of these two ways comes with its own set of complications and risks. Disabling it can be done by means of an 'EGR Delete', or by defeating it yourself.

    An 'EGR Delete' can be performed by a non-OEM shop costing you in the $8,000 - $15,000 price range. An EGR delete is the proper way to completely remove the EGR and DPF systems. Cover plates are installed where the components used to be, a muffler replaces the DPF, and the ECM is reprogrammed. The benefit is generally longer engine life, improved fuel mileage (by up to 1 mpg on some engines), and no more EGR related downtime, maintenance, or repairs. One of the downsides is that if the EPA or CARB sees that this has been done, you will face huge fines and be shut down until it is put back to OEM standards. Another downside is that you will never be able to take your truck to a dealer or OEM engine shop again. They are required by law to flash your ECM back to the factory settings, rendering the engine inoperable without the EGR components. Despite these downsides, there are many who take the risk and have it done, but those are are generally truck owners that had multiple EGR related failures with no solution. Understanding your EGR system well will avoid this completely, so the choice is really a matter of education.

    Defeating your EGR yourself can improve your fuel economy almost as much as an EGR Delete, and has much lower EPA and CARB consequences because it can be undone very easily. It usually involves performing some voodoo engine sequence along with disconnecting your EGR valve and/or some sensor(s). The benefit is improved engine life and fuel economy, amusing it does not cause your DPF to malfunction or stop its ability to Regen. If your truck does not have a DPF, or it does not effect your Regen or DPF system, then defeating it is definitely a viable option, but not without taking a few other serious precautions. Knowing how the ECM is going to react and monitoring your exhaust temperatures while driving is the key to actually getting the benefits without risking a serious turbo or EGR cooler failure. With the EGR disabled, that 570 degree 'sweet spot' exhaust temperature is no longer maintained. The engine will run on only clean air, allowing the fuel to burn very hot, improving its efficiency and reducing soot. Exhaust temps can easily reach 1300+ degrees, especially if you are climbing a hill. These much higher exhaust temps will have to be monitored while driving to prevent excess heat buildup on your EGR cooler and your turbo. It is not a difficult thing to do at all, but will require you to install a 'Pyro' gauge in your dash. I recommend putting the sensor right on the outside of exhaust manifold, near the turbo using a pipe or hose clamp rather than actually drilling a hole into your exhaust and putting it inside. What needs to be monitored is the heat buildup, not the actual exhaust temp. Just as a reference, Holset turbo specs say that the newer VGT turbochargers can withstand exhaust temps of 1350 Fahrenheit for a period of up to 3 minutes. This means that the casing and/or your exhaust manifold can get to roughly 850 degrees without damaging the turbo. The next thing you will need to know is how the ECM is going to react to all this. First, the ECM is going to complain by turning on your engine warning light. With the warning light on all the time, you will have to keep a close eye on your fluid levels and other things to ensure you don't get an unexpected engine shutdown alarm. Assuming your engine is not already derated by the disconnected components, since your exhaust temps can get so much higher, you need to know that your ECM will limit your torque if you try to climb a hill with your foot all the way on the floor and the exhaust gets upwards of 1400 degrees. This is to protect your turbo, and is counterproductive to saving you fuel. That is another reason why you need to keep your manifold temp below 850 degrees yourself, so that you do not run into this problem.

    Summing it up, Disconnecting your EGR will cost you the price of a Pyro gauge for monitoring the temp of the exhaust manifold. It will also force you to drive up hills in the correct gear for maximum fuel efficiency, keeping exhaust temps to a minimum. On really long gradual hills, you may on occasion, need to down shift a gear and use a higher rpm if your Pyro gauge reaches 850. Always, before shutting off your engine, you will need to glance at your Pyro gauge to ensure your manifold temp is below 500 degrees (400 is recommended). If it is not, then you will have to idle a few minutes to let it cool. This protects your turbo bearings and protects your EGR cooler. Like I say, not impossible to live with, but sometimes annoying. Is it worth it? Personally, I think so because even without the EGR disconnected, you should be driving efficiently and allowing your engine to cool before shutting it down anyways. It is up to you to decide, it is your truck.

    If your truck is 2007 or newer, it has a Diesel Particulate Filter (DPF), a Diesel Oxidation Catalyst (DOC), and a Dosing Injector (After-treatment Injector). All of it combined is referred to as the Exhaust Aftertreatment System. This system is in place to further reduce emissions and to catch all the soot produced by an EGR engine. The After-treatment system itself is NOT part of the EGR system, so this means that DPF and/or Regen alarms will usually only occur if the DPF system itself is unable to function properly due to, a problem within itself, coolant intrusion from a bad EGR cooler or a cracked head, or if it has been disabled by the ECM because of a safety related engine issue like excess engine temp, excess oil temp, excess fuel temperatures, or bad DPF sensor readings. Other EGR or engine related issues will not generally cause Regen problems if the After-treatment system is able to function normally. Excess soot caused by an engine problem can cause the DPF to clog up, but only if the problem is fairly significant. If you, or the repair shop suspects this, then it can easily be checked by simply disconnecting the exhaust pipe from the DPF and looking to see how much black smoke comes out when the engine is revved up high. A small to medium puff of soot is normal when the fuel pedal is pressed suddenly, but constant, or large amounts of soot can in fact cause problems. An oil sample from the engine can also reveal excess soot problems as well, so it is a good idea to do an oil analysis, checking for excess soot and coolant intrusion, when trying to solve DPF issues.

    The DPF itself is only part of that 'can' that looks like a big muffler under your truck. The front part of that can is actually the DOC. The DPF is nothing more than a ceramic 'soot catcher'. Yes, it is made of ceramic similar to the honey-comb of a bee hive. Smacking the outside of it with a hammer, or if road debris hits it, then it will crack that rather expensive, difficult to manufacture honey comb brick. Attached to each end of it are 2 small stainless tubes going to a sensor known as the DPF Differential Pressure Sensor. That sensor tells the ECM how clogged up this soot catcher is. Also, there are 2 or sometimes 3 Temperature sensors to monitor how hot the exhaust is going in and out.

    The Diesel Oxidation Catalyst (DOC) is attached to the front of the DPF inside the exhaust can. It is the diesel engine equivalent to a Catalytic Converter on a car. It converts harmful exhaust gases into less harmful ones and has an optimum or 'sweet spot' temperature that makes it work efficiently. Any more than 50 degrees above or below 570 Fahrenheit, and it doesn't function well, so this is exactly why the EGR system on your engine tries to regulate the exhaust temperature at 570 degrees. A temperature sensor is usually mounted on it (sometimes also used as the DPF inlet temp sensor) to let the ECM know if the EGR system is doing its job. A Regen cycle does not remove the soot from your DOC, so if your DPF ever has to be removed and cleaned, then the DOC needs to be removed and cleaned as well so that it doesn't create a loss in fuel economy or get packed with soot.

    The After-treatment Injector is mounted directly behind the turbo and is really the only active component in the After-treatment System. It isn't like the engine injectors, but rather more similar to the spray nozzle of a hair spray can. During a Regen cycle it activates, spraying fuel into the exhaust pipe as a fine mist. If everything is working properly, the fuel will igniting at the DPF and not inside the pipe, burning out the trapped soot that has accumulated. The soot is converted into Carbon Dioxide and gets pushed out the exhaust stack. This injector is the key to keeping the after-treatment system functioning properly, but unfortunately, it is exposed to all the soot and other bad things that can end up in your exhaust. It is not uncommon for this injector to start clogging up at around the 250-300k mileage on many trucks. After that, it is just a matter of time before you start to see those proverbial Regen Lights in your dash. Some of the engine makers suggest cleaning it every 200k miles, and this is good advice, but cleaning them involves shutting the truck down, draining the coolant, removing it, replacing the gasket(s), and if you are lucky, getting it clean enough to last another 200k miles. For a couple hundred bucks, I have always just recommended replacing them. Removing it and replacing it is actually not difficult. There is a small coolant line that connects to it, so if you are going to tackle replacing it yourself, you will need a couple 5 gallon buckets to drain your coolant into first. Since it will be replaced more than once during the trucks lifespan, I recommend some high temperature anti-seize on the screws and fittings as well.

    What exactly is a 'Regen'? A Regen cycle is a cleaning cycle performed on your DPF to get rid of the excess soot that builds up in it. There are actually 3 basic types of Regens. They are Passive, Active, and Forced. A passive Regen is performed by your truck about every 350 – 400 miles depending on the make and model truck you have, whenever you are driving. There is usually no indication whatsoever that it is happening, and if you are not one to idle your truck very much, this passive Regen should be enough to always keep your DPF cleaned. If you ever get a 'Parked Regen' light on your dash, and you don't idle your truck much, then it is a definite sign that it is time to take a close look or perhaps replace your after-treatment Injector. If that looks good, or is new, then you need to find out why the passive Regen cycle is being interrupted and/or delayed by your ECM. Not taking an active approach to this will definitely cause your truck to end up in a Derate, or worse, an engine shutdown, putting you in a shop for major repairs before it is over with. If you do idle your truck a lot, then an occasional Parked Regen light might be ok. In either case, I recommend holding off on actually doing a Parked Regen unless you have driven about 300 miles and it has not gone out. Your only short term solution if you are getting Parked Regen alarms that do not go away after you start driving, or if they return frequently, is to actually perform a Parked Regen, but to right away, have your after-treatment injector inspected and/or replaced as soon as you can. Shutting your truck down for this costs downtime, so to prevent repeating failures, you should do an 'EGR Tuneup' just to ensure you have all the basics covered. Since you now know that your truck will do a 'Passive Regen' every 350 miles or so, getting a Derate or DPF warning every 350 miles will clearly indicate there is a problem in your After-treatment system.

    A 'Parked Regen' is the truck's way of forcing you to manually Regen your after-treatment system to clean it because the Passive Regen in unable to keep up. If your Injector is good, and there are no cracks or gaps in the exhaust system, then a Passive Regen is more than enough to keep the system clean. This means that Parked Regen warnings or requests are actually your first sign that things aren't quite right. Also this means that you are loosing fuel economy from the restriction of soot in your DPF. A Parked Regen will usually take 20+ minutes to complete, even on a healthy DPF system. The reason is that the truck needs to raise the temperature of the DPF to above 500 degrees before fuel injection can take place. Then, it usually takes another 10 minutes of spraying fuel into the DPF to get it clean, raising its temperature above 1,000 degrees Fahrenheit. How long it takes to perform this Regen is totally dependent on how fast it can get the DPF to reach these temperatures. If your truck takes more than 1 hour, then there is definitely something wrong.

    A 'Forced Regen' can be done by the driver on some trucks, but not always. This type of Regen is a last resort effort to remove soot from the DPF when there are other things wrong. If your engine has disabled the Regen system because of another fault (like excess fuel temperature), then a Forced Regen may get you rolling again temporarily, but your problems will likely return in 300-400 miles when the Passive Regen fails again. It is quite often that repair shops will blame your truck problems on just simply the fact that your truck needed a 'Forced Regen'. NOTHING CAN BE FURTHER FROM THE TRUTH!. Don't be fooled by this. You ARE going to end up in the shop again in a very short order. If a Forced Regen has to be performed, then something else is very wrong. The entire EGR and DPF system will need a thorough looking at, starting with the after-treatment injector and/or EGR cooler. Your DPF can in fact get clogged with ash itself, but that usually takes 800+k miles or more to happen. Removing the DPF itself and having it cleaned should be as a last resort item only after performing a Forced Regen using a new injector. Simply removing the DPF can cause it to crack its ceramic interior, costing you thousands for a new one.

    Problems with SCR/DEF (Diesel Exhaust Fluid) systems are many.
    Personally, I have never owned a truck with one of these systems, so I cannot elaborate on them much. I do know that the fluid itself likes to crystallize and clog up the components, so keeping the DEF tank full, keeping the cap clean, and having the filters and/or injector cleaned regularly is probably a good idea. Using some common sense, thinking pro-actively will help you stay on top of these types of systems so they do not fail you when you need them the most. Understanding them thoroughly will definitely save you thousands upon thousands in repair bills and down time. Stay well informed, and get the correct information for your particular truck. Your extra efforts will be always rewarded in the money you save.
  5. Rawze

    Rawze Medium Load Member

    Jun 29, 2013
    I stopped mine from going bad. I run waterless coolant and vented my reservoir for a Zero Pressure system. I think this improved fuel mileage actually for me a tiny bit, but cannot prove it.
    Diesellee Thanks this.
  6. logtrucker25

    logtrucker25 Light Load Member

    Jul 27, 2009
    northern CA
    Thanks a lot for the information. I just got my first truck with egr/dpf (2009 ISX 550) and want to learn about them and this answered all my questions
    Rawze Thanks this.
  7. Blind Driver

    Blind Driver Road Train Member

    Aug 7, 2006
    New Albany, IN
    I'll bet some one is thinking "Where are all these sensors located and what do they look like" :biggrin_25521:

    A few pics may be helpful.
    UCM, Rawze and Charli Girl Thank this.
  8. Rawze

    Rawze Medium Load Member

    Jun 29, 2013
    I will be at the TA truck-stop outside Portland,OR today, tomorrow, and looks like maybe Saturday is anyone wants to stop by and say hello. Just PM me.
    MOGLAR and Diesellee Thank this.
  9. Big Lou

    Big Lou Light Load Member

    Aug 15, 2013
    Tampa, Florida
    I am burning 2 gallons of oil between oil changes of 15,000 miles? any help would be appreciated.I have a 2010 Peterbilt cummins 450 isx cm 871
  10. Markvfl

    Markvfl Road Train Member

    Nov 29, 2007
    Apopka, FL
    Hi Rawze, I replaced the Delta P and MAP sensors and cleaned the other one that looks like a pin on the intake side. It's amazing how much soot was on them! Cleaned the tubes from the Delta P to the manifold but didn't pull the manifold to clean it. I just got the truck back from putting 2 new cams in it at 377,000 miles and should have done this when it was apart. I did ask them to decarbon the intake but doubt that they did it and I went fishing for 3 days so... Hell, they didn't even change the oil after having the engine half apart! Had the ECM read and they said the ECM history says the DPF is regenning properly but I would like to run a forced regen just to be sure but don't know how. I have a 2009 Peterbilt. They also said that the lifetime idle % is 43%. I just bought it 3 months ago and try not to idle. It seems that no matter how I run the engine - in 12th at 1350 to 1400 (55 - 57mph) or in 13th at 1250 - 1300 (60 - 62) it runs and pulls the same and gets the same fuel mileage - high 5s to low 6s. I'll be in Denver on Monday. If you're passing that way going back east I'd love to meet up with you even if I have to wait a day or two. Thanks!
    Last edited by a moderator: Mar 5, 2014
    Rawze and Big Lou Thank this.
  11. Heavyd

    Heavyd Road Train Member

    Feb 4, 2009
    Big Lou, you may need to have this looked into. That kind of oil consumption is very serious. You should be having the blow-by checked. Low quality of oil will burn away naturally as it breaks down after that kind of mileage, so make sure you are using the proper grade and a respectable brand. Whatever has happened, the damage is likely already done. Usually the cross-hatch on the cylinder liner has been polished away, and/or the rings are seized to the pistons from carbon packing. We have seen this from improperly timed engines, or faulty injectors that are spraying fuel out onto the cylinder wall, turning to carbon and getting packed into the ring lands on the pistons jamming up the rings. Exceptionally dirty EGR systems could also be to blame. Engine dusting is another possibility, check the intake pipes for signs of dirt or dust ingestion. You will start to see a increase in fuel consumption and decrease in power, if you haven't already. It is likely you are looking at an overhaul. If it does get torn down and the cylinders are glazed over, I recommend to replace all 6 injectors and make sure they check the static injection timing. This is now the preferred way to set up the injector camshaft timing as the original timing wedges normally used are not precise enough.
    yb226, Rawze and cuya Thank this.
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