Cm2250 boost dilemma

[Geared_Cortex]

Hi ,
Please enlighten me.
My friend has a pete 386 2012 cm2250 485hp deleted from before he got it. Recently his turbo actuator died so he bought a rebuilt one from a reputable place. A mechanic he knows installed it using cummins software. The thing is that when he is empty going up a hill the boost goes up to 38-40psi and backs off and stays around 36psi . But when he's underload going up a hill then it goes up to 28/30psi and backs off to stays around 26psi.
Is it normal on those engines or something is not right? If so what could it be?
Thanks

[Rawze]

something is not right. A 2250 should never see more then 36 psi... otherwise you can kiss that engine goodbye after a while... it is over-boosting.

NEXT< it should not be spiking like that at all then dropping back. Maybe an older style air actuated CM870 turbo with its wonky air operated VG turbo will do this a bit, but not any of the newer style electronic controlled turbo's should ever be doing this.

Lastly, if all you get is 30 psi boost under full loads, then something is either wrong with the turbo, the intake or exhaust , or the programming in the ecm is bad. ... take your pick.


Unknown, most likely bad delete from the typical butcher shop... for all you know, your program maybe bad,.. and the dammned SCR can and/or DPF may not be hollowed out all the way, causing issues. Does the power and boost go up if you remove the down-pipe off the back of the turbo and take it on a test run? --- Might want to pull out those cans and make sure all 3 (DOC. DPF. and SCR) are 100% hollow to the metal.

Lastly, what other hardware changes were made? -- EGR cooler still there? - Any block plates installed? and where are they located? --- etc.etc.etc.


One place to start would be to pull a copy of the program out of it and e-mail it to me 90% chances are that you have a bad program, even if it happens to not be the cause of the boost issues and needs to be addressed all on its own. I will review it and let you know if there is issue with it or not.

Next would be to pull apart that exhaust system and ensure all the cans are hollow .. including the SCR can. Most shops are too damnned lazy to hollow the scr properly, or do dumb s$it like only make a 4" hole thru the center of the elements like complete dip$shits!... check all elbow pipes for chunks of broken dpf elements, check the decomp tube for blockage, etc.

Replace the intake air filter, check the CAC and intake for boost leaks, check the exhaust for blockages ... etc.

[Geared_Cortex]

I will send you that delete asap and start removing those pipes for inspection . Thank you for taking the time.