So my 07 cobalt is having boost issues. It use to have 20 psi and now it only has 5 psi. I can't figure out whats wrong. I replaced the vacuum bypass tubes. But I cant seem to find the supercharger bypass actuator valve online to figure out if the actuator bypass is causing the problem. Does anyone know where I might be able to find this part? I have a 2007 chevy cobalt ss supercharged, 2.0 engine.

 

What pulley were you on hitting 20 PSI?

 

If you have the factory boost gauge, you are not hitting 20PSI. That gauge is computer controlled and estimates the boost pressure in the manifold, but does not give you true boost pressure. You need a scantool and check all of the following sensors: MASS AIR, S/C Inlet, MAP, BARO, Throttle POS...