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+--- Thread: CM870 Turbo Boost (/showthread.php?tid=8889)
CM870 Turbo Boost - Hemiterry - 04-30-2023
Hey everyone, I have an 06 International 5600I tandem dump truck with a stock tuned, mandated recently installed CM870 long block. The truck has an Allison RDS six speed transmission. The truck runs stronger than ever and gets better as it breaks in except in one situation. When I’m climbing a long steep hill in fourth gear the engine pulls strong with around 32psi boost at around 1600 rpm’s. When the transmission downshifts to 3rd gear on the steepest part of the hill my RPM’s go up to around 2000 but my boost drops to about 22psi. It seems to me the boost should go up instead of dropping. This is a brand new Cummins OEM VGT turbo. Before the new motor I used to never get below 40mph fully loaded on these same hills but now I’m down to 30mph! In every other situation besides these longer hills the truck is stronger than ever. Any ideas?
Thanks, Terry
RE: CM870 Turbo Boost - Rawze - 04-30-2023
you were not very clear on it. Does it have a 100% OEM factory program in it?, or something someone made/put in to delete the egr so that the check engine lights go away with egr-valve unplugged, etc?.
- The typical garbage-can egr-delete programs out there are notorious for doing what you describe on the 870's. ... which is about 95% of all programs for the CM870 that these idiots use and share around off those horrible auto/truck tuning wwwsites, etc.
more info on this: http://rawze.com/forums/showthread.php?tid=8370&pid=72522#pid72522
RE: CM870 Turbo Boost - Hemiterry - 04-30-2023
What’s the best way for me to find out if it is truly OEM tuned? My mechanic told me it was a stock tune but he’s been wrong on things in the past. Can I pull the ECM and take it to Cummins for them to check or restore to factory settings?
RE: CM870 Turbo Boost - trucklogger2 - 04-30-2023
(04-30-2023 )Hemiterry Wrote: Hey everyone, I have an 06 International 5600I tandem dump truck with a stock tuned, mandated recently installed CM870 long block. The truck has an Allison RDS six speed transmission. The truck runs stronger than ever and gets better as it breaks in except in one situation. When I’m climbing a long steep hill in fourth gear the engine pulls strong with around 32psi boost at around 1600 rpm’s. When the transmission downshifts to 3rd gear on the steepest part of the hill my RPM’s go up to around 2000 but my boost drops to about 22psi. It seems to me the boost should go up instead of dropping. This is a brand new Cummins OEM VGT turbo. Before the new motor I used to never get below 40mph fully loaded on these same hills but now I’m down to 30mph! In every other situation besides these longer hills the truck is stronger than ever. Any ideas?
Thanks, Terry
Yes it’s normal for boost to drop down as revs increase kinda of starting near 1600
When they put charge air piping together they may have not checked for boost leaks so it may be a good idea to go around all the joints that are clamped and feel for leaks
Check at at least 1300 rpm
RE: CM870 Turbo Boost - Rawze - 04-30-2023
(04-30-2023 )Hemiterry Wrote: What’s the best way for me to find out if it is truly OEM tuned? My mechanic told me it was a stock tune but he’s been wrong on things in the past. Can I pull the ECM and take it to Cummins for them to check or restore to factory settings?
unplug the egr valve and see if you get a fault for it.
RE: CM870 Turbo Boost - Hemiterry - 05-01-2023
Ok I’ll do that first thing tomorrow