Tuned CM2250 chuffing/missing/popping
07-20-2021, (Subject: Tuned CM2250 chuffing/missing/popping ) 
Post: #1
Tuned CM2250 chuffing/missing/popping
So I've got a cm2250 that I'm trying to figure out whats going on. It has been de-mandated for a few years now. A few months ago the high pressure pump was about ready to fall off, i replaced it with cummins reman. 2 weeks later the turbo started chuffing intermittently with lots of black smoke when pulling over 50% throttle and under 1500rpm. Shortly after this started the ecm was throwing boost pressure sensor codes, checked it all out and the ecm was bad. Installed a freshly tuned used one, that fixed the boost code but not the chuffing. Shortly after that the turbo actuator and vanes in the turbo went bad so it got a Cummins reman turbo. The chuffing was still happening so we checked out the air to air, it was cracked, got it replaced and ran an overhead. Kind of running out of ideas at this point. Any thoughts???

Parts replaced:
high pressure fuel pump
turbo and actuator
#3 injector
air to air and all boots
throttle position sensor
exhaust backpressure sensor
07-20-2021, (Subject: Tuned CM2250 chuffing/missing/popping ) 
Post: #2
RE: Tuned CM2250 chuffing/missing/popping
the de-mandate and its 90+% likely horrible programming is a far bigger problem to start looking into immediately more-so than the turbo acting up.

ref: http://rawze.com/forums/showthread.php?t...5#pid13255

What is the turbo position at idle?... and the turbo position while its "chuffing"? ... HECK... What engine mode is it trying to operate in?, as a chuffing turbo is a sign that its in the wrong mode, considering its de-mandated, and TRYING TO WARM-UP THE SCR SYSTEM!

- How much boost does it make under max engine loads? ... What are oil temps doing ?.. who de-mandated it ?... what was done to the hardware? -- Is the SCR can gutted all the way to the metal 100%? (common mistake from a lot of half-arssed delete shops not to hollow it out 100% all the way).. the DPF?.. the DOC... is there block plate installed somewhere?... and where?

Anyone bothered to pressurize the whole engine up at 30 PSI and check the whole system instead of just the CAC?

Anyone bother to replace the IMAP and exhaust gas pressure sensors?.. and ensure the exhaust pressure sensor circuit thru the thermostat housing is not clogged up?

It sounds to me like there is some kind of serious lack of understanding of how these newer engines work, how to troubleshoot them, etc. on the part of the person working on that thing.

First thing is to pull a copy of the program out of that ecm (using CT) and e-mail it to me for a proper review.. That is the first place to start. Without knowing exactly what is in the ECM.. you will have no idea what that engine is trying to do to itself. YOur post so far shows all signs pointing towards bad de-mandate programming that has finally caught up to the fact from your descriptions so far. Replacing the ECM does not help if the program that went back in was just as bad as the one that came out of it. For all you know, it could have jumped into one of the engines SCR warm-up modes and is now stuck there permanently.

Most of those garbage-can bad deletes do not re-map the engine mode control logic at all and then a year or 2 later.. the damn engine is confused as f$uck and trying to wamr up a DPf that is no longer underneath the thing once one of the disabled (or unplugged) sensors start giving ghost feedback / reading incorrectly into the ECM due to lack of use.

Here is what it takes to properly de-mandate one: http://rawze.com/forums/showthread.php?t...7#pid58347

Garbage-can, engine killing deletes at their best!. See it on a daily basis around here.

here is also a pic of a screen-file for CT that anyone can make themselves that will tell you what engine mode, etc. and all the other important data that is telling the engine what to do... http://rawze.com/forums/showthread.php?t...6#pid28636


There are proper procedures and methods for the ISX... learn them well... follow them to the letter ... and there will not be any more blind-man mysteries and guessing at s$it in the dark.

User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.

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