Air control valve

[Rawze]

They aren't junk. At least not the OEM ones any ways.

The turbo control valve on the CM870's do go bad after several years, they usually last about 6-8 years on an otherwise healthy engine.

They also start acting up if your air system is not pristine. Dirty air / moisture, etc. or poor pressure regulation, etc. running thru them eventually gets to them, causing them to act up or go bad.

CM870's have always been wonky with the turbo. That is why they went away from that design and went to electronic control.

Things have to be just right for them to run and run well... including the air supply, the actuator, the turbo mechanism itself .. and don't forget about the programming. Bad delete programming is a plague for those engines and this alone can make one start acting funny all of the sudden too.

Everything from the air pressures to the electronics to the ecm and the mechanical components has to be in good shape for them to operate like they are supposed to.

the engine is also supposed to have 36-38 PSI sustained boost while in a hard pull too. Any silent derates in the ecm (a common derate/symptom of unplugging the egr or a using bad delete program) and it will typically spike and then will fall back to 32-psi or less.