In an earlier post I was concerned that my SS wasn't making the correct amount of boost. I took it to the dealer today and everything checked out fine according to them. I am wondering if I am reading the guage wrong. I stated I was seeing no more than 5 psi but then after leaving the dealer I got to thinking. At cruising speed the gauge is showing 10 on vacume when I punch it it goes to 5 psi on pressure. Does this equate to 15 psi, being 10 psi to get back to 0 and then the extra 5 psi = 15 psi? Sorry guys this is the first turbo vehicle I have owned. I'm a little confused.

 

No, 10" of vacuum is just that, 0 is the same as the atmosphere, which is what a normal car would have at full throttle, and anything more than that to the plus side is positive pressure, or boost. So 5 psi of boost is 5psi over 0. You should then see what the others see, or depending on conditions, anything from 10-almost 20 psi on the guage.

Vacuum is created when the throttle is partly open, because the engine is trying to pull more air than the throttle will let is have, that creates suction, or vacuum. The harder it pulls, the higher the vacuum number, which means the more suction. Most engines will have around 16-20" of vacuum at idle, dropping to 10-14 when idling in gear(autos). The less vacuum, the more load on the engine. Going up a hill, or full throttle may drop vacuum to 0 on a normal engine. In a turbo engine, anytime you have positive pressure(boost) the turbo is actually supplying more air into the engine than it could suck in by itself, hense the extra hp.

 

You either have a bad boost gauge or boost leak(s) if you are only spiking to 5 lbs of boost. Believe it or not turbo cars can and will come from the factory with boost leaks. Check all of the clamps on your hoses, especially the intercooler and zip tie any vacuum hoses without any clamps. Actually, you should replace crappy factory worm drive hose clamps with T bolt clamps. I come from the world of PT turbos (I had a modified 280 hp '03 PT GT) and the Neon SRT-4 (I have a modified 336 hp '05 SRT-4). We make boost leak checkers that clamp onto the turbo to check for leaks throughout the engine.

 

so this was a Chevy dealer, right?
I remember you were concerned about being their guinea pig... so maybe you should take it to a Pontiac dealer and tell them what the Chevy dealer said. Sounds like white heat was right, you might have a bad boost gauge or boost leak. 5 lbs of boost ain't right.

 

Hopefully you get the point. Your dealer is not correcting the problem and you need to insist they do. There are channels for problem resolution if they are non-responsive. Don't try any fixes on your own, this is a warranty issue and they are required to make it right. There are at least two bulletins on Troubleshooting the guage and boost reading. There are only two fixes according to the bulletins (although suggestions of leaks are certainly valid possibilities), 1) The guage is bad (my guess, since mine is bad and being replaced), or 2) The ECM is bad. The minimum you should see is 12 psi at boost, but more typically 15-16 psi near sea level, and 20 psi at high altitude.

 

I can`t say about the SS but I had a 1.9 turbo and at 60 mph it had 5 psi of boost and when you steped on it it went to 12 psi.I NEVER saw any vaccum when the car was in gear and and going down the road so that does not seem right when you are showing vaccum to me.

 

Vacuum reading is normal at part throttle or off throttle. Takes a slight load, or acceleration to take it up to "0' or above. Your guage may have been set up differently than the SS.

 

Yeah I'm pretty pissed about the whole thing guys and I appreciate the responses so far. I feel like the dealer just doesn't want to fool with it and along with the mess they put me through to get it I'm pretty much done with them. I have a local Chevy dealer that has always done great work for me in the past. I'll probably take it to them and have them look it over. I don't have to take it to the dealer I bought it from do I? I mean I have heard of some dealers refusing to work on vehicles unless you bought it from them. Not saying this dealer would do that just wondering out loud. I guess if they can't solve it them I will contact GM customer Service.

 

I bought my HHR at a very small dealer 15 miles away. Never taken it there for oil or issues with the HHR. Went to local dealer most of time instead except for time I was out of town. My advice go to dealer you like or feel is better