About 5 months ago I purchased a 2010 ss w/ GM upgrade (has Bosch sensors). Since is been so cold and icy out I haven't really been paying attention to how its boosting. No CELs, not acting funny, just not 20+ psi like everyone else. Its still under extended warranty, I just don't really know how to explain its a problem. To them(the dealer) they say 17 is normal... Any thoughts? help? First post BTW, long time lurker.

 

Just tell the dealership that after diong allot of research that boosting to 20 is normal for a HHR SS w the upgrade. you can also talk to the salesman and sales manager the issue and just ask to reflash the GMTU upgrade and see if it changes.
since they didnt do the initial work they may not have it on file and may have to pay for it and that may be the issue. i dont know how dealers work.
maybe someone that works at a dealership can chime in here

 

Don't know if this helps but you could try this to check if the boost is hitting the correct numbers.

Dial up the hp/torque gauge on the RPD. Take the car for a test run. Get a couple of good runs on a good straightaway.
If the RPD is hitting in the 290hp, 310tq. range then that is normal(you may want a rider to go with you to watch the gauge)

These cars have a torque management system. Even with the GMTU. If the car will put down those numbers with 17lbs. boost, then that's all the computer will allow. Weather, air quality, temperature etc. can effect your boost numbers. Mine only reaches 19lbs with the GMTU and I thought I was "losing" some power. After swapping e-mails with a GM Perf. division engineer, he assured me that I didn't have an issue. He said I was most likely getting all the hp/tq that the computer would allow.

And remember. You won't get full boost in 1st gear(auto or 5 speed) That's just the management system easing off the boost. Doubt you could get any traction in 1st with full boost. It would just burn the tires off.

Let us know what you find.

 

Thanks guys.
Ill give what fireman suggested a try(sounds fun). Then Ill take it to the dealer if the numbers are low.

 

I was told about the torque management too but ended up with a boost leak. Definitely check the HP reading. If it's hitting 290hp then that's probably fine . If not, you have an issue. If you have an automatic get on a highway, cruise up to 60mph release the throttle them punch it. I can normally boost 23psi. Same thing at 35mph. These Cars and this GM tune can be finicky though. Trial and error