CM870 ghost derate

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This is my first time on here, so I hope I don’t screw up too bad. I have a 2005 Pete 378 with a 475 ISX CM870. I’ve been fighting this truck for a long time and I’m at an impass. Truck loses power not long after taking off. It is derating although there is no CEL. I can pull over and restart the truck and she runs great with good power for a mile or so and then same thing, it just loses power like a derate. I’ve heard of a “ghost” derate but don’t know where to start. I just bought this truck and have no history, but someone has been fighting it before me. I’ve found and repaired numerous issues, but can’t get to the source of what it’s doing now. Nearly every setting in the ECM had been messed with and was wrong. I’ve even sent the ECM out to be repaired and they said it’s good. Is there anyone here willing to point me in the right direction, I’ve not seen this before.

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Update: I’ve acquired Insite and it’s showing me something I could not see with my generic scanner. Turbo compressor Inlet Air Temp is at 59 degrees F and I replaced the sensor and same thing. Also, turbo compressor outlet air temp (calculated) shows 406 degrees F even when truck is cold. Does anyone know what could cause this? Is it possible someone has “egr deleted” this truck? I can perform a egr test and the valve opens and closes fine.

[Rawze]

(09-21-2022 )ads1 Wrote:  Update: I’ve acquired Insite and it’s showing me something I could not see with my generic scanner. Turbo compressor Inlet Air Temp is at 59 degrees F and I replaced the sensor and same thing. Also, turbo compressor outlet air temp (calculated) shows 406 degrees F even when truck is cold. Does anyone know what could cause this? Is it possible someone has “egr deleted” this truck? I can perform a egr test and the valve opens and closes fine.

those sound like symptoms of a typical bad delete perhaps.

Start by taking the truck to the OEM stealers$it and have the correct program flashed into it that belongs to the engine according to its ser#. A CM870 will not shut down if it has been deleted.. it will only have a CEL light on + a boost derate but not a power derate.



Also.. you may simply be chasing a ghost any ways. There may actually be noting wrong, as some programs for the ISX are set to only give you full power/torque for a short period of time (30 seconds to 1 minute).. and then back itself off. It is called the 'Smart Torque" feature, and many engines came with this setting permanently turned on.

if there is an actual derate then you need to watch the life fuel flow (mg/stroke) in Insite + the engine state parameter, plus the turbo rpm + boost pressure and see how it fairs out as it starts falling off.

Also: the ISX will hold fuel back if the boost is wonky .. and those CM870's are notorious for wonky boost .. especially if it has a bad delete program in it.. or if the boost controller is starting to go bad.. or if the turbo arm is starting to hang up on it.

Also, If the EGR is still active on it then it could be the EGR valve acting up, causing power loss.


Also, if the truck is old then the exhaust back-pressure sensor siccuit might be clogged up that runs thru the thermostat housing. They are notorious for this and it makes the turbo act wonky... leading to efficiency losses and power issues.


-=== Ie.. take you pick and start working thru the list.

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I’ll go down your list and get back to you. I appreciate your help. To be more explanatory about the lack of power it won’t hold high gear bobtail. If you pull over and shut it off it will run very good a mile or two maybe then like you flip a switch it loses power to a point I can’t maintain highway speed. No check engine light. No codes in ecm. What are your thoughts about the turbo air temperatures not changing and where would those values come from? This is what made me wonder if a egr delete had been done. That, and the fact that every setting in the computer was messed up (I mean like the a/c controlling the engine fan was disabled as was the manual switch and all kinds of other incorrect settings. I’ve cleaned the exhaust pressure port and sensor, I’ve replaced the intake manifold pressure sensor and turbo inlet pressure sensor both with Cummins parts, I’ve resealed the injectors due to dark fuel, after doing the bubble test hand cranking and with the starter, ran the overhead and that helped too, but this instant power derate is puzzling me.
I’ve flushed out the old fuel and refilled, I’ve used manual fuel pressure gauge, all good. I’m probably going to have to pull the ecm and take it to Cummins like you said unless you know how I can use Insite to somehow download a known good program. Again, thanks for your help, and I saw a post where you have been ill. I hope you recover and prosper in good health.

[Bengy88]

If you don’t know anything about insite it’s too risky for someone to just give you the file and tell you how to flash it….. if you follow rawze’ steps then you will probably find your issue. Do you have a boost guage installed? If it’s got a half ass demandate in it whos to say the egr wasn’t blocked properly and you aren’t loosing boost through the valve opening under pressure? You may want to make sure your egr has been blocked properly as well. That is assuming the egr is deleted

[Bengy88]

If you want I can remotely hook to your truck if you have a way to be connected to internet and I’ll monitor some things and see if I see something obvious. It will be a few days before I can though. Got some personal things going on and haven’t been able to help people like I like to… at least for a couple more days

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(09-21-2022 )Bengy88 Wrote:  If you don’t know anything about insite it’s too risky for someone to just give you the file and tell you how to flash it….. if you follow rawze’ steps then you will probably find your issue. Do you have a boost guage installed? If it’s got a half ass demandate in it whos to say the egr wasn’t blocked properly and you aren’t loosing boost through the valve opening under pressure? You may want to make sure your egr has been blocked properly as well. That is assuming the egr is deleted

I am new to Insite, but have been working on trucks many years. I’ve been using a Texa program for the last couple of years which lets me modify any parameters, but it has no provision to deal with software. I’d like to learn about how to do more with Insite at some point. As far as the EGR valve goes, all I can say is I removed it and cleaned it and while it was off I used Texa to open and close it. Worked good. The problem I’m having happens suddenly. Like you flip a switch. It will stay like that from then on. I go from good power to probably 1/2 power instantly. If I pull over and cycle the ignition I instantly have full power again. Lasts maybe a mile or two max and back to low power. Can do that over and over. No check engine light, no codes. The only thing I’m seeing that’s not right is the turbo como intake temp stays at 59 degrees no matter what, and I replaced the sensor, no effect, and the turbo compressor out temp calculated is like 400 and something degrees no matter what even when the truck is ice cold. I’m guessing I have a software issue. I’m going to either find someone to help me try something with Insite, or I’m going to pull the ECM and go to Cummins for a new download file.

[Rawze]

when is the last time it had the egr circuits replaced?.. the Delta-P sensor and feed tubes for it?... that can cause it too, if it in fact not deleted.

try driving it with the EGR temperature sensor unplugged and see if some of its issues clear up. The CEL will be on, but the entire EGR system will switch itself off.

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(09-21-2022 )Rawze Wrote:  when is the last time it had the egr circuits replaced?.. the Delta-P sensor and feed tubes for it?... that can cause it too, if it in fact not deleted.

try driving it with the EGR temperature sensor unplugged and see if some of its issues clear up. The CEL will be on, but the entire EGR system will switch itself off.

I’ll try that tomorrow if I have time. Shop is full right now. It’s so aggravating when you know it’s something that is electrical but it won’t throw a check engine light. Any thoughts on why my turbo inlet temp is stuck at 59 degrees and turbo outlet (calculated) stuck at 400 and something? Cold or hot that’s what they show, never move. Inlet sensor is new genuine Cummins.