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+--- Thread: Cummins ism cm875 weird running (/showthread.php?tid=10757)
Cummins ism cm875 weird running - Celticsevad - 09-19-2026
Ism 2005 egr deleted
Valve lash and injector replaced 2 weeks ago
First start in the morning after the valve job i had no boost until air tank are full, then i shut the engine off and start it is ok
1 week later, sudden loss of boost , egt skyrocking and cant get the boost back , or only after 15 start stop of the engine
Then i quit and come home to look at it
Found Cummins / Holset air control valve connector with bad connections,
My question is : does that failed air control valve can make the engine crank weird (like no compression sometimes) and when it start , white smoke all around the turbo exhaust side, and will want to die on first fuel pedal press.
I usually see intake pressure 0.78 at key on, then 1.44 on start, now i have 0 on both.
Replaced intake pressure sensor ,and barometric sensor, at idle it have suction in the hole of intake sensor(normal or not?) Can it be caused by the Cummins / Holset air control valve not working?
Should i look somewhere else like fuel lines under the truck... all help would be a lot appreciated
3 mechanics had a look at it and cant help me at all
RE: Cummins ism cm875 weird running - Celticsevad - 09-19-2026
Update i found the little metal hose that goes from exhaust manifold to exhaust gas pressure sensor to be loose and broken on the thread adapter inside the manifold , can it be a cause?
RE: Cummins ism cm875 weird running - Celticsevad - 09-19-2026
Found fuel pump shutoff valve not clicking on key on...might be the issue, will check tomorrow
RE: Cummins ism cm875 weird running - Rawze - 09-20-2026
80% of all de-mandate programming is problematic and/or harmful to the engine over time...
maybe put factory programming back in it and fix its issues first. Get it running well again. ... then, for old engines like that prior to 2007, seek out forum member 'running rough' to have a proper de-mandate program made for it again. He is set up to do the really old (pre 2007 era) stuffs around here.
RE: Cummins ism cm875 weird running - Celticsevad - 09-20-2026
(09-20-2026 )Rawze Wrote: 80% of all de-mandate programming is problematic and/or harmful to the engine over time...
maybe put factory programming back in it and fix its issues first. Get it running well again. ... then, for old engines like that prior to 2007, seek out forum member 'running rough' to have a proper de-mandate program made for it again. He is set up to do the really old (pre 2007 era) stuffs around here.
Thanks for your reply rawze the king! , got here from one of your youtube video, forgot to say that the truck is fully egr deleted blocked, yeah its a 2005 ism cm875, i saw you do programming i think? May i extract my tune from the ecm and you look at it ? I think the ecm egr delete was not done properly, bought the truck 2 years ago and issues started 2 months ago with bad injector and then all this followed up. I know my engine is over fueling at around 1300rpm because egt going up and boost going down for a bit then goes back to normal, then there is still that egr temp sensor check engine... do you know if egr pressure sensor still need to be running in my setup, found the egr pressure sensor metal tube to be loose on the manifold threads, and i would need to tap that fitting bigger since the threads are gone
Appreciated help sir!
RE: Cummins ism cm875 weird running - Rawze - 09-21-2026
(09-20-2026 )Celticsevad Wrote: Thanks for your reply rawze the king! , got here from one of your youtube video, forgot to say that the truck is fully egr deleted blocked, yeah its a 2005 ism cm875, i saw you do programming i think? May i extract my tune from the ecm and you look at it ? I think the ecm egr delete was not done properly, bought the truck 2 years ago and issues started 2 months ago with bad injector and then all this followed up. I know my engine is over fueling at around 1300rpm because egt going up and boost going down for a bit then goes back to normal, then there is still that egr temp sensor check engine... do you know if egr pressure sensor still need to be running in my setup, found the egr pressure sensor metal tube to be loose on the manifold threads, and i would need to tap that fitting bigger since the threads are gone
Appreciated help sir!
CM875 is similar to a CM870 when it comes to programming, turbo type, etc. ...
related info: https://rawze.com/forums/showthread.php?tid=7704&pid=67571#pid67571
RE: Cummins ism cm875 weird running - Celticsevad - 09-21-2026
Well nothing helped for the fuel pump selenoid.. still looking for fix
RE: Cummins ism cm875 weird running - Celticsevad - Yesterday
Found a 4" small crack in the fuel tank near the pickup line fitting, might be my issue!!!!