Cm870 demandated hot egts

[Upnorth83]

I love this site. I read threads for fun on here. I know my problems are not original. I just feel like I pissed you off and I apologize.

[Upnorth83]

The 40 41 pounds of boost is abnormal that’s why I mentioned it as well. Usually 38 is normal pulling hard at around 1350 1400 rpm, much higher rpm and boost falls off a lil bit. I pull 105500 through the mountains daily.

[Rawze]

(11-11-2024 )Upnorth83 Wrote:  This is what I was referring to with the cold weather https://rawze.com/forums/showthread.php?...5#pid24825

- That is a known issue for -20c(extreme cold) temps and below only. /,.. so your assumption on that thread is a bit mis-guided.

- ALSO.. any decent de-mandate would have addressed that issue as well.

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Your boost issue (high EGT's and high oil temps) is IS MOST LIKELY bad programming ./.. its THIS>>>

Rawze Wrote:What you are describing is the most common derate that CM870 engines get. It is very well known.

If the CM870 goes into a boost derate then the boost will typically jump up to about 36+ psi(normal boost for a few moments) in a pull, then fall on its face back to 29, maybe 30-32 psi (much lower). It is the most common derate those things will do.

This can happen because someone unplugged the egr valve or has defeated the egr in some way. EGT's also will skyrocket when it happens, and this is very hard on the turbo.

Like I said.. It is a very well known condition with CM870's, and a person would think that after 15+ years of them being out there in trucks.. that even some of the complete morons who are half-arsse making de-mandate (delete) programs for them would know this by now.. but that is not the case at all.

-= Someone's half-arssed delete programming that mostly only hides the check engine lights from showing in the dash will not fix that derate. Bad programming like that only makes things worse+ significantly shortens the life of the engine and its turbocharger due to garbage settings.

The problem is in the ram memory of the ecm itself, and not even in the programming/flash file at all. CM870's are special that way, and very few people understand them properly.

- There are about 10-12 settings or so in the RAM MEMORY ONLY that need to be changed, and can only be done while connected to the ecm live. They are not part of any flash file. It is an auxiliary (silent derate) EMISSIONS LIMITER that kicks every time it boosts up to normal levels, making the boost fall back again TO LIMIT EMISSIONS. It kicks in automatically (as it is not part of any flash file) whenever someone puts a delete file into the ecm.

IT CAN BE FIXED AND THE AUX. EMISSIONS DERATE SHUT OFF PROPERLY.. BUT IT TAKES EDITING THE ECM LIVE!.

I have been trying to educate those godd$amn clowns who do custom engine tuning for CM870's for years about this exact and well known problem, but none of them seem to give a damn, past taking someone's moneys to simply hide fault codes, and them blaming all the problems on the engine or its turbo... mostly because they are so stupid, and it lends itself towards selling you after-garbage crap mods!.

ref: http://rawze.com/forums/showthread.php?t...2#pid72522


Your HIGH OIL TEMPS is this...
ref: http://rawze.com/forums/showthread.php?t...6#pid78036
BAD PROGRAMMING!!!.

AND YOU PUTTING ON AN AFTER-GARBAGE COOLER mods on it HIDES THE HIGH OIL TEMPS ISSUE, SO NOW YOU CANNOT TELL, AND WILL NOT KNOW WHEN THE ISSUES GETS FIXED PROPERLY!!!.

[Upnorth83]

I want to give an update on this. Rawze was correct as usual. I had a horrible tune. They had timing way advanced and they had tons of faults blocked!! None of the ROM derates were done either. Bengy has been helping me figure it out like a champ. Once the crap was removed I found that I also had other problems. I kept getting faults for low voltage to vgt controller and fan actuator. I replaced oem harness to ecm because that’s where the fan circuit was ran and after doing diagnostics tree in insite I got some strange results. I also replaced fan actuator. After this it was suggested to splice power and ground in to the engine harness in the vgt circuit. After doing all this codes still kept coming back but only when the rpm’s hit 1800 rpm’s out the engine was cold. Also I kept getting voltage high or shorted to high source to Jake solenoids. The Jake fault would hit hundreds of times just glad on and off. I took the entire engine harness apart looking for rubs and shorts and found nothing. Finally I borrowed a test ecm and installed it. I went for a test drive and could not get one fault to hit, where as before I could trip the faults like a light switch I knew exactly hope to set them off. I have since installed a new reman ecm from cummins and am waiting for a flash will update after. Also want to thank Rawze and Bengy88 for all your help and smarts. This whole experience has sparked an interest of learning more about these engine systems and programming. You guys are amazing!!! Thank you.

[Mr Hagg]

I also see that alot of these 870's will have the cam timing wrong aswell. Some of them ran a 6/6 timing and some 4/6... And when someone flashes a file set up for the 4/6 in a 6/6 truck it will cause temps to be higher and smoke more...

[Upnorth83]

Yeah my cam timing is set at 4 6 when I rebuilt it and put new cams in it.

[Upnorth83]

Yeah mine I set to 4 and 6 when I rebuilt it and put new cams in it.

[Rawze]

(12-26-2024 )Upnorth83 Wrote:  Yeah mine I set to 4 and 6 when I rebuilt it and put new cams in it.

For the CM870's, it goes by your engine CPL. The program in the ecm must match the profile as well.

.. here is an old post with the official CPL vs. Wedge numbers...
ref: http://rawze.com/forums/showthread.php?t...6#pid29926