Fixing your DPF Problems in a nutshell...

[Rawze]

Cummns ISX CM871: The solution to most EGR problems in a nut shell (by Rawze)...


How does one prevent the endless cycle of EGR/DPF problems, and to keep their fuel mileage at its peak?,...


Well, actually, both go hand-in hand believe it or not. If there is something on your engine that has lowered your fuel mileage, then that same something is causing your engine to produce excess soot. Any time there is excess soot, it accelerates all the problems that are seen with the EGR and DPF systems. The CM871, even if it is running perfectly healthy, is in a constant state of slowly degrading these systems because of its EGR design. What I mean by this, is that the EGR itself chokes the engine from burning the fuel clean, which results in soot. This soot builds up quickly in the oil, causing excess wear and buildup in a lot of components. Hot, sooty exhaust gas is recirculated (EGR = Exhaust Gas Recirculation) back into the intake of the engine. It runs through through several pipes, components and sensors, and soot builds up in them, causing the engine to eventually loose performance and fuel mileage. This drop in performance then creates even more soot, witch builds up in the components even faster, choking these systems even more. it becomes a sort-of runaway train effect. The more soot build-up, the more soot produced, the higher soot produced, the more soot build-up. Its an endless cycle that causes tons of EGR, DPF, and fuel mileage problems.

Unfortunately, the only solution to this non-stop problem in this motor is to take apart all these systems and clean them out regularly. Most repair shops do not want to be bothered with such things as removing a pipe just to clean it, and others do not understand that this is major problem. It will almost always be them blaming the big ticket items like a bad turbo, or something else expensive to replace.

Here is a video i made with someone that is a prime example of this...







This problem is so bad, that even on a brand new engine running perfectly well, it only takes about 150 - 200k miles before the soot build-up in all the components start to take their toll. This means that at about every 200k miles or so, if something isn't done about it, then all of the problems typically seen with this motor start to show their ugly head. Some of the symptoms include unexplained low fuel mileage, DPF and regen issues, Repeating EGR or other Component failures, Power loss, hesitation in acceleration, and/or many other problems and ghosts. This problem of soot buildup extends all the way from the exhaust, back around to the intake manifold itself, where the air needed to run the engine itself is slowly choked off. Its like someone trying to run a marathon while they are being choked and can hardly breath. So how does a truck owner deal with this?,...and What needs to be done?,...

Just about the only way to prevent this is to do a regular 'EGR Tune-up'. It is something nit not recognized officially by the engine makers, and therefore not preformed by the trained professionals of most shops. This leaves the problem to the truck owner to perform.

Is it the answer to ALL EGR/DPF related problems?,...NO,...but it IS THE PREVENTION OF SUCH PROBLEMS FROM HAPPENING... As well, if it hasn't been done at all, and the engine has many tens of thousands of miles on it, then it can definitely be the root cause of repeating other problems with the EGR/DPF.

Here are the youtube videos I made showing how to do this EGR Tune-up with some explination. Maybe it helps someone out there with fuel mileage and/or DPF problems...

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Do a thourough EGR Tune-up!,.. Don't just replace a couple sensors and assume that's all it was!!!,... ALL OF IT NEEDS TO BE DONE TO GET THE ENGINE RUNNING RIGHT!!!.. It is VERY important you get those pipes and intake manifold cleaned out!!!. It chokes the system down and causes the engine to loose fuel mileage and perform poor regens.



Here is the video on how to do the Doser Injector...











-- If your truck has more then 400k miles on it,..... Don't Forget about the EGR Valve!!! It clogs up as well, and you need to either replace it or clean it out...







After you have done an 'EGR Tune-up', replacing the after-treatment injector, EGR deferential pressure sensor, Cleaned or replaced the Doser Injector, the EGR Valve, and cleaned/replaced the IMAP sensor and/or Exhaust gas pressure sensor, it is a very good idea to go ahead and perform a 'Forced Regen' on the truck using the Cummins Insite Software. Here is a video on how it should be done PROPERLY!,...

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Take note of the Kpa reading after the Regen is complete. It should be less than 2.5 with a new injector, and certainly less than 3.0 overall. A Brand new DPF will read 1.0-1.5, so if your getting readings below 2.0 at all, its a very good sign that your DPF is in good shape.


Perform a thorough Cylinder Cut-Out Test....


Make sure your engine and injectors are in good health!. If the engine itself is running like crap, then the Tune-up will not completely cure your problems. Perform a thorough cylinder cut-out test to see the health of the injectors and cylinders. If they are producing too much soot, then it will cause endless DPF/DOC face-plug problems as well. Here is the best procedure using Insite...

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The Infamous DOC Face-plug (cry-baby) alarm!...

Code:

FAULT CODE 2637
After-treatment Diesel Oxidation Catalyst Face Plugged - Root Cause Not Known

This is truly a 'Cry-Baby' Alarm!. The 871 loves to throw this alarm whenever ANYTHING on the engine could be wrong. Once it throws this alarm, as well, The passive regen system will shut down, and 250 engine hours later, your engine will derate/shut down with a DPF plugged alarm, because it is no longer performing regens. If you perform a thorough EGR tune-up, and replace all the sensors, Doser injector, etc. like recommended, ensured all your cylinders are healthy, and the rest of the engine is running good, then this alarm should go away. If it keeps coming back, then it could actually be a legitimate alarm. Usually, though, it is on trucks that have with more than 450k+ miles. The DOC does NOT last forever, and does in fact need cleaning once in a while too. Unfortunately, you have to remove it and take it to a shop for cleaning (best done together with the DPF). It also does not last more than 450-600k miles before just simply starting to go bad. The reason why, is that the more oil your engine burns because of engine wear, the faster it makes the DOC go bad. The platinum inside the DOC gets eaten away by engine oil additives, and coated over by any coolant leaks that might you might have had. Also, If your turbo is leaking oil, or your engine is consuming oil by any more than about 1 gallon every 5000 miles or so, then you will see regular DOC face-plug alarms. Does this mean you need to replace it?,... Well, if it is old, then likely yes, but replacing it is NOT going to make the alarms go away completely if your engine consumes oil. It is more likely, you will have to do a forced regen cycle on your truck once a week to keep the alarms at bay. This means that owning an Inline-5 adapter and a copy of Insite is the likely the only way to keep the system healthy long term if your engine is aged and consuming a bit of oil.


Other causes of EGR problems...

-- Not as common, but just as important,.... You ALSO Have a Differential Pressure Sensor at the DPF can. It is fed by two (roughly 1/4 inch dia.) stainless-looking tubes, on either end of the DPF, with short rubber hoses at the ends, under the sensor. This Sensor CAN and DOES go bad too. I recommend replacing it about every 400 - 500k miles at the most. As well, make sure the tubes are not broken, or the rubber ends at the sensor are n good shape and NOT LEAKING. In any event, You should probably inspect it very well (remove and look inside it for soot, buildup, etc.) if your still having frequent regen problems.


-- Leaking exhaust piping is one of the more common causes of regular DPF/DOC alarms when the rest of the engine is healthy. Performing a forced Regen, then going outside the truck while the Doser injector is 'ON' is a good time to spot exhaust leaks that effect regens. When fuel from the After-treatment injector is spraying into the exhaust sytem, if there are any leaks, you will see them as puffs of white smoke coming from your exhaust flex pipe or joints. If you see this, then the regen cycle is NOT going to perform correctly. You cannot have leaks in your exhaust system if you want your DPF to stay clean.

Most of the time, an EGR Tune-up will cure your DPF/EGR problems, but there are other things in the engine that can cause problems as well. Usually they are the more obvious kind like a leaky/cracked charge air (Air-to-Air) cooler, failed injector, or perhaps damaged exhaust or EGR piping. Many mechanics are quick to blame the turbo as well, but it usually has to be pretty bad before it actually causes EGR/DPF problems. Most of the time, its a sticky EGR valve, or a leaky EGR cooler instead. Lastly, the injector cam itself, if it has slipped (it isn't keyed), can be the cause of EGR/DPF problems, but it is combined with excess soot problems in the engine as well.