CM870 VGT Actuator

[Rawze]

(02-07-2019 )Lonestar10 Wrote:  My dads 2007 T600KW CM870 popped up with some codes for the VGT air actuator and it wasnt working correctly so it was replaced. New OEM air actuator put on now he says his boost doesnt go as high as it used to when pulling only gets up around 30-32 where it used to run 35-37. Truck is a bone stock cummins 500/1650 Tune only thing changed was the air actuator. turbo was replaced last year in the spring.


any ideas? thanks for any info!

first of all, you can test the movement of the actuator and turbo arm by making an adapter and pressuring it with a regulator form 0 to 60 psi (0 to max arm movement). If it does not operate smoothly or it takes a different pressure range to operate it,.. that would explain some of the issue.

next, if you put an air pressure gauge in the line between the actuator and the operating cylinder, you can see what the ecu is commanding (0 - 60 psi = 0 - 100% closed). if you get something different then the actuator is likely bad.


Lastly, there are a couple different variations of controllers for the CM870. Some required an external regulator, some did not. Could be the supply line regulator is going bad, or the filter that is in line with it.


just some things to consider,.. i don't own one of those engines, have not worked on them much, and am about 4 beers into the evening here.