ok so my boost control solenoid went back a while back, so I replaced it with the one off my k04, I'm on zfr, anyway that fixed the issue, I bought a replacement efr solenoid and finally tried it today. car boosted ridiculously slow, like hits 15 and slowly creeps up to 28 by 6k rpm finally. so I put k04 one back and it works fine again. what the heck? did I get a lemon or what can be the issue there

 

Old thread, I know. Tom, what did this end up being? I am suspecting my less then one year old solenoid is bad

 

Hello. So i have a 2006 cobalt ss/sc my recent issue is a loss of power every now an then it shifts hard( going into a gear there is major resistance so going into neutral then back to the gear is ok) but I have a check engine light on and about 3 weeks ago I had autozone check codes an they told me it was my timing chain but someone at a local shop told me its the vvt sensor or something. Any ideas of what would cause a loss of power or how i could better diagnose the issue.