Hello everyone. I hope I'm posting in the correct place about my issue. I have a 09 SS/TC. For sometime now my car hasn't been producing full boost. I bought the car about 3 years ago and it already had a few mods. (Injen CAI, Injen charge pipe and a GM Stage 1 tune). I know with that tune the car should have roughly 21psi. My car now will not get over 14-14.8 lbs of boost. And it sounds as if the BPV is always open. Hence the whistling sound. I get DTC P0299(turbo under boost) and P0101 from time to time. During a drive cycle the car will go into limp mode and not have any boost at all. I have to shut off the ignition and cut it back on to be able to have some kind of boost. This is my second cobalt SS. My first had a trifecta tune and I never had any issues. Any input as too why this may be happening is greatly appreciated.

 

Are you sure you don't have any leaks in the system? Get it pressure tested and confirm.

 

Sounds like you may have a leak as ^he said.

 

I haven't had a chance to break down the induction system as my car is my DD. So I haven't had a chance to look for any cracks, holes, etc. that may be causing the boost problem. I did however hook my BPV straight to manifold and there was no change. Still not getting full boost. I'm hoping that I can tear down the induction system this weekend and inspect. Any other suggestions from the community is appreciated.

 

If it has the stock intercooler still, it's possible the endtanks may have cracked. You can try and look under and see. Possible the bar at the bottom caught a curb or a pothole and broke off, making a nice hole with it.

Not saying you hit a curb, just things that commonly happen.

 

It has a ZZP intercooler. I've had time so far this weekend to disassemble all the charge piping ( upper, lower), removed the intake and intercooler. I've visually inspected every piece with no visible holes or cracks on any piece. Today I'm going to pressure test every piece of piping. I have a suspicion that I may be getting a leak from the boost pressure sensor on the lower charge pipe I've noticed that the sensor doesn't sit flat on the surface of the pipe when tightened down with the screw. When tightened the opposite side of the sensor moves up from the surface and you can clearly see the hole it goes into. I'm thinking air is getting past the o-ring and and leaking. Hopefully more to follow today. And thank you guys for your continued input.