Isx cm870 boost in and out

[tsolson]

mine was the turbo air controller. but check it for leaks, and make sure there are no leaks in the air line running from the turbo controller to the air actuator on the turbo. Mine is a low mount, on the LH side of the motor, behind the frame rail, at the front of the engine. They changed some to a high mount, not sure what you have.

with mine, if I shut the engine off, and restarted it, then it would boost normally for a while, then it would quit again. I replaced the controller, and it fixed the problem. last one I bought was $1100 CAD, and I'm sure they haven't gotten any cheaper. Cummins did replace one on parts warranty for me, but i think those days are over now too, unless they diagnose it for you in their shop.