Cm870

[RDTAZ87]

Hello Everybody, I have a 2005 KW w900 with a de-man cm870 Isx. Its has a brand new overhaul and as soon as I start it up its good for about 30-60 seconds with very good throttle response. After those seconds pass by, throttle pedal seems to be kind of delayed and starts to miss but does not turn off. If I take it for a drive like that it soon misses more and eventually turns off. I turn it back on and no issues for the 30-60 seconds. As soon as I turn the key off again and turn back up i have noticed is good on each start up before the 60 seconds. Do you think its a electrical problem that it resets in each startup then detects a malfunction after the 30-60 seconds?

Ive overhauled it everything is new including mechanical fuel Pump, lift pump, injectors, fuel lines, ifsm is brand new,fuel solenoids, sensors, timing actuators are all new, I can’t thing of what might be wrong. I’ve even changed about 4ecms and was was calibrated 4 different times also. Im sure out of options now. Can somebody please help me figure out this issue?

[Rawze]

...

If it is dying randomly, .. it does not matter that you tried 4 different ecm's... it could still be an ecm issue. Engines that run a bit and then stumble and die, is a typical symptom for an ecm that is going bad due to excess vibration or age, and it can be easily checked for. Just crank it up and then smack the ecm hard.. hard enough to almost dent its casing.. and see if it stumbles or dies. If it does then it is a bad ecm. CM870 and CM871 ecm's are notorious for this as they get old or suffer too much vibration due to some moron never replacing the crank shaft damper every 500k miles or so like they should have.

Matter of fact, I saw someone go thru 6 ecm's (they kept taking them from other trucks or buying them from repair shops or other online paces instead of directly from cummins), and engine still dies on them. It was not until they purchased an official OEM ecm from cummins that they got one that did not have this issue when they smacked the top of it.
here is a picture of roughly where to smack it...



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Ruling out the ecm for a moment...

Last resort is to monitor all the data inside the ecm with a proper screen file in calterm and determine what is controlling the fueling, engine mode control, etc., live while it acts up. Your description of it 'changing after 60-seconds' points strongly towards it changing engine operating modes improperly for one reason or another.. and it should not do this .. especially if it were actually properly de-mandated, hence the bad delete statements above. This (due to pi$$ poor garbage programming) could very well could be what is happening.

here is a screen shot of what to monitor to see what that ecm is actually doing ...
ref: http://rawze.com/forums/showthread.php?t...3#pid58693

[RDTAZ87]

Thank you Rawze for your well detailed information! I will definitely try that ecm test and if it dies after it or stumbles, I will get with Cummins and order one. I’ll try and reach tbe forum member as well. It really should be some kind of electrical/ecm/programming issue for sure. Thank you sir!