Cummins X15 after treatment issues

[Envirotec]

Hi Everyone,

Where do I begin… I’ve been having issues with the after treatment systems on 4 of my tractors. (21, 22, 24, 25).

21 has 426k miles. I figured to have DOC and DPF baked because of the mileage. Did that about a month ago and then threw a code for too much soot in DPF (several quarts worth). Prior to me baking them out, there were no issues or codes with DPF or DOC. Also when I brought DOC and DPF to shop they said filters were in great shape prior to cleaning. They also gave me the sheet with all the tests they did before and after baking. Also, the truck seems to always be in the operating state of after treatment regeneration. No lights on dash but when I plug in with INSITE it shows the turbo running at roughly 60,000 rpm and engine “idling” at 750 when supposed to be 650rpm. I took DPF and DOC off and blew everything out with shop air just to get it going as I had a total of three trucks down (I know I’m throwing a band aid on the issue which I never do). Then about a week later one of my drivers lost oil pressure and I find out there’s 28 gallons of “oil” in the oil pan. Supposed to be 11. Have it at a shop now putting all new injectors and high pressure fuel pump. I don’t think the aftertreatment issue is related, so when I get the truck back, I think I’m going to have to still deal with After Treatment Issues.


22 has 270k miles. Truck for over a year sounded like it was always regenerating. Turbo always spooled high just like 21 above. So I bring to my local dealer which is an absolute nightmare to say the least. The day I bring to the dealer, the radiator leaked coolant so they replaced that along with “fixing” the turbo being spooled all the time when sitting at “idle” 750rpm. They told me the reason for this was due to a worn camshaft. So they replaced camshaft and adjusted valves. Get the truck back, just for it to shutdown on the road due to clogged DPF. So I get DPF and DOC baked. And it runs good for about 2 weeks until I get a code for aftertreatment system. Differential pressure least severe level. I clear the code knowing I’m going to have a bigger problem in my hands in the next few days.


24 has about 300k miles. Truck had a MIL light on for about 6months for DPF differential pressure. Finally brought to a shop and they told me they had to replace the DPF and DOC. This was about 6 months ago. The truck ran for a week or so until the whole “idle” thing like 21 and 22 happened with this tractor too. Take the DPF and DOC off to find tremendous amount of soot like 21. Blow it all out with shop air and code comes back which I was expecting. But the code was for the SCR. I cleared it. It came back. I cleared it again. Then a different code came back for DEF doser voltage. Cleared that. Then came back also. All bandaids I know..

25 has about 325k and had a MIL light on similar to 24 for DPF. A couple weeks ago the truck shutdown while driving (unrelated to After Treatment. Tranny issue). Had to tow back to our yard. While it was down in the shop I took DPF and DOC to shop to bake. I reinstalled (just like other trucks above). Put everything back and light is still on. Also reset filter and DOC in INSITE.


Overall, getting hit all at once here and it’s strange how it is all happening after the DPF and DOC was either cleaned or replaced. I’ve been doing research after research trying to figure it out. Especially, that I’m fairly new to the whole after treatment process. I can’t bring trucks to dealer anymore which forced me to buy INSITE, Quickserve, and Service Ranger. I also have a full time mechanic but he is old school and not tech savvy.

After discovering Rawze and watching all the EGR videos yesterday, I think I might be able to find the solution with the help of everyone on this forum. Just trying to keep our fleet and plants running but this after treatment crap is getting way out of hand. Any feedback is greatly appreciated!!!

Thank you,
Derek

[hookliftpete]

Have any of the trucks had the egr system cleaned and all egr sensors replaced up to this point? That likely would have prevented much of your issues.

[Rawze]

The aftertreatment systems collects soot.. not generates it.

Attacking clogged up filters (The DOC and DPF) only temporarily reduces the accumulation, and does not solve the problems of the engine making excessive soot.

An EGR/engine tune-up needs to happen to bring the truck, its engine, and its emissions systems to their former glory.. and no repair shop is going to do that.

Its like your calling the fire department because the whole forest behind your house is on fire, and all they do is put out the one tree next to your house, and tell you to call them back over and over (so they can milk you for all the moneys you are worth, charging you a fee each time), instead of taking care of the bigger picture.

Sad part is that it is not their fault. They are not trained to deal with an engine that is causing the excessive soot, yet has no immediate faults for it. They are only trained to attack the cans under the truck over and over and sell you expensive parts when you complain.


ALSO: If your old-school mechanic does not have the skills to actually troubleshoot modern equipment + use modern diag. tools on engines that have now been the norm for 15+ years these days ... then that person needs to GO!!> FIRE THEM, or tell them to get with the times and bring themselves up to speed REAL FAST!. or find someone else that actually knows how to use a computer and troubleshoot.

==============


START by performing EGR tune-up work.

STOP GUESSING AND TAKING YOUR TRUCKS to the typical repair shops that have the training and brains of a squirrel.

I also noticed that you are accusing the engine of revving up its turbo at idle. THIS IS ACTUALLY SUPPOSED TO HAPPEN for rapid warm-up of the DPF, DOC canisters ... although it is not supposed to be excessive. Again .. if it is excessive.. then that points right back to the ENGINE having issues with its EGR system due to excessive soot buildup in the egr cooler, piping, sensors, etc.. covered and clogged with soot, and not reading right. -> and NOT the cans under the truck.

HOW OFTEN is the engine's EGR system taken apart and cleaned all out?.... HOW OFTEN is the IMAP and other egr sensors cleaned or replaced?. -- Again, that is almost always where the culprit is and not those exhaust cans alone.

There are exceptions to this. If the engine is bleeding fuel, coolant, and/or oil into its exhaust, it will clog the systems quickly. However this is easily observed by taking pictures of the clogged faces of the components + posting them here.. and analyzing any buildup to see if it is coolant, oil, etc. ... this will tell someone this right away.

Your descriptions so far however, seem to point towards engine neglect most of all though.

AND: When is the last time the guts of the fuel pump were replaced on the engine with more than 400k miles?. - The fuel pump guts need replacing (plungers, rollers, tappets) every 400,000 miles or 8,000 run hours.. regardless of condition to prevent catastrophic engine failures and metal shavings (without warning) getting into the oil and eating everything up.

Also, if you had a premature overhead cam failure.. THAT IS YET ANOTHER SIGN ON NEGLECT!. perhaps your guru old-school mechanic has no idea how to do all of the preventative maintenance, required tune-up work, etc. on modern engines?.. this sounds to me like your biggest issue at this point. #1 cause of overhead cam failures is neglect of the crank case filter.. allowing too much crank case pressure to build up in the engine for one reason or another. Another is overhead valve adjustments not done every 2 years or 250k miles. = neglect.

more info on EGR tune-up;;;
http://rawze.com/forums/showthread.php?tid=7&pid=9#pid9

Checking the fuel rail and the injectors to ensure they are not bleeding excessive fuel and making excessive soot...
: http://rawze.com/forums/showthread.php?t...3#pid75483

Then following this up with CAC leak tests, EGR system leak tests.. DPF, SCR, DOC sensors cleaning, inspections, and replacement as needed,. etc.etc.etc.

followed by checking the DEF system and the decomp tube to ensure it is not clogging up too...
ref: http://rawze.com/forums/showthread.php?t...07#pid1807

Last but not least.. also posting the regen history on here, + maybe the graph of engine usage etc. from one of the trucks,. etc. for further discussions on how healthy the systems really are. Maybe some history on how much these things are idled, what type of truck operations & how much stop/go driving, etc.etc. rear end ratios and rpm's typically driven, etc., too.

[JimT]

Well, I had a reply with some of the same stuff as Rawze, so instead of repeating I'll just add a couple things.

Many people overlook the role of the SCR components/system. A lot of that turbo spooling you say is regen related, it's actually more likely the warmup/keep warm function of the SCR system. Especially when you hear it kick in when sitting idle of traffic lights during stop and go city driving. It does this to keep the SCR temp high enough to allow more efficient NOx conversion. If the outlet NOx sensor is faulty or just reading higher then targeted NOx emissions or maybe the SCR temp sensor, then the ECM will adjust operation of the engine/turbo and EGR to compensate. Blockages or DEF buildup in the SCR system can also cause exhaust restriction issues further up the line in the DPF/DOC, the turbo and of course the engine itself.

One of the most important things to learn is that ALL of these systems need to function 100% correctly and work together by sending data back to the ECM which will adjust various aspects of operation.

A lot of the modern engine operation is dictated not by soot and DPF operation but instead by stricter and stricter NOx emission standards. The DOC/DPF and soot collection requirements really haven't changed much since their introduction, other than maybe shrinking in size and increased operational efficiency. I mention this because many of the design and operational choices for these newer engines reflect the NOx emissions requirements. The push for lower RPM engine operation is bad for engine longevity, but helps reduce NOx production (and the manufacturers don't care, it helps them hit the government targets and they just get to sell you more parts and engines as a result). But lower RPM operation (more torque, less HP) also tends to yield more soot, therefore more work for the DPF. --- Now add taller gear ratios and drivers that have been brainwashed (or actually forced due to RPM limiters) to lug the engine and you get faster engine wear. That engine wear leads to increased oil consumption, which adds even more soot to the exhaust.

The point here is that due to stricter emissions standards the systems are hyper sensitive and are constantly adjusting to try to stay in balance, even shiny new from the factory. But they can only react to the data they have and with the programming built into the ECM. You can't ignore warning signs, such as the MIL coming on (especially not for 6-12 months!). You also need to be proactive to ensure optimal operation of the entire system, both mechanically and electronically. You also need to train your drivers on the best way to operate these trucks, otherwise their driving habits will be at odds with the ECM's attempted operation and will directly contribute to repeated breakdowns.

Oh, and don't buy into that extended oil drain crap. Having a worn camshaft at 270k mi is directly related to excessive soot buildup in the oil. A bypass oil filter will help reduce the soot, but the oil itself breaks down over time and loses it's helpful additives. You need to stay with normal drain intervals, 8-15k miles, dependent on fuel mileage.

[Envirotec]

Unfortunately the answer to every question is NEVER!

In regards to fuel pump, I am looking for someone to test if the pump is actually bad and maybe repair? From what I’ve been told, these newer pumps can’t be tested?? The oldest truck is a 2018 and newest is a 2024. Anyways, super appreciative of the feedback!!!! Been pulling my hair out for the last 2 years with mechanic issues!! I will also try and take some photos off INSITE when I can. Any particular screens you would like to see? Again, I’m no expert myself so pretty new to INSITE and other programs.

[JimT]

Also, DON'T blow out the DOC/DPF/SCR cans with shop air! It damages the filters. They are not just straight through passages. Blowing shop air through them can cause blowouts in the narrow passages and turns used to collect the soot. Basically rendering them useless.

[Envirotec]

We change oil and all filters every 12k. I actually have old cam shaft in shop from that one truck. Also to add to the list the we’ve never done a valve adjustment….. I was told every 100k??

[Rawze]

(05-06-2024 )Envirotec Wrote:  We change oil and all filters every 12k. I actually have old cam shaft in shop from that one truck. Also to add to the list the we’ve never done a valve adjustment….. I was told every 100k??

The red engine maker says 500k for an ISX ... but this has been proven time and again to be WAAAY too long of an interval.

Its every 250k or 2 years.

[Envirotec]

(05-06-2024 )JimT Wrote:  Also, DON'T blow out the DOC/DPF/SCR cans with shop air! It damages the filters. They are not just straight through passages. Blowing shop air through them can cause blowouts in the narrow passages and turns used to collect the soot. Basically rendering them useless.