My car is a 2004 MC SS 3.8 and thePSI boost gauge seems to be reading too high all the time now. Even at low speeds it hangs around the 10-11 oclock range (between -10 and 0).
At idle it is a little above the -10 mark and it used to always be at -10.
The car idles fine, gas mileage is OK but it reads a lot higher than it used too. Recently the garage replaced the oil pan gasket and had to drop the exhaust headers, undo motor mounts, lift the engine and disconnect a bunch of stuff just to replace the oil pan gasket. I am wondering if there is some vacuum line or valve somewhere that maybe was not reconnected all the way or a air leak causing it to show such high readings. We live in a hilly area and I have to give the car a lot of gas sometimes to avoid lugging the engine on step hills. It is also making a more continuous low rumble type of sound. That might be the new tires but it just seems like maybe the turbo charger is making the noise. I had a tech change the fluid and no change. I trust the local garage but now I wonder if they missed something when the put it back together after the oil pan gasket change.

 

I'm assuming you mean super charger not turbo charger, if you feel there is something wrong take it back and let them diagnose it. That will have to be free of charge as they caused this new problem.

 

If the number you're reading on your gauge was normally -10, it is perfectly fine to be -10.5 or -11. That means you have MORE vacuum, so they probably fixed a leak if I'm understanding you correctly.

 

What happens is it never goes back to zero and it keeps staying at around the 10 oclock range up to noon - if you look at it like it was a clock. So it will jump to around -5 then up to 0 on the smallest of accelerations. If I kind of feather the gas it will drop down some but it is reading way to high than ever before.
I used to never see it climb unless I had to punch it to pass or something that required some fast acceleration. Just last night driving normal around 45mph with my tach around 1300 the PSI boost was half way up at about the 0 or 12oclock range. That reading would usually be high if I had to pass somebody. Any thoughts. I had the fluid changed and that made no difference.

 

I’m having this same issue with my 05 SC SS. Did you ever manage to resolve this on yours? I had the intake gasket replaced as well as the oil pan so when I saw that someone had the same issue after the same repair I figured it’s probably not just coincidence.