CM870 Turbo Underspeed and Overspeed

[Rawze]

(03-23-2026 )pwhittle Wrote:  Thanks Rawze,

It has been maxing out at 32 PSI since 2017 when I bought it (2005 model).

I don’t think it is the exhaust. I replaced the factory muffler with an (non-OE replacement) a couple years ago.

Hopefully not the turbo. It could be the CAC or a leak. I’ll keep looking.

Paul

also straight pipe that exhaust and see if boost picks up or codes go away. Your super-super muffler might me part of the issue for all anyone knows.

also,.. you need to see if the program for the engine actually belongs in that engine. Many times, ppl will 'uprate' the power in the engine improperly, and it causes issues like your having due to turbo or other hardware mis-match in the program itself.

What is the program in the ECM that is showing at the window title bar when connectd with Insite?. .. What is the engine ser#?.