The shop called me back. Granted they are not experts (by their own admission) on superchargers, but they had some ideas.
On a side note, even with the car on the lift and in drive, the supercharger doesn't kick in, so they were somewhat guessing as well. They did say that it does not seem to be doing damage to the engine as it didn't sound like any sort of "normal" noise they they encounter ever.
So they said that it is about a $500 "gamble" that what they think it might be actually fixes the problem.
Their thoughts were: Wastegate Valve and Control Solenoid, plus a couple of new air hoses.
I swear that I replaced the solenoid already once, but it kicked a code at the time (an easy fix with a price of about $35 from Rock Auto). The "wastegate valve" sounds like a "turbo" part, and not a supercharger part and I can't seem to find reference to it anywhere. Not sure if they meant the bypass valve??
I would need to source the hose, but all in all, about $110 in the 2 main parts, and then some hose and a pretty easy fix, IF that fixes it. Since the solenoid is the only thing that connects back to the computer, it is the only thing that would kick a code of some sort. If it is working (since my boost isn't limited and I am not getting a code), then the valve and maybe hoses seem like the next logical thing to try. Again, not saying that it will actually fix anything.
EDIT: I DID replace the solenoid already, but that was 4 years ago per this post: http://www.grandprixforums.net/threa...-valve-trouble
EDIT: Unless it needs a replacement "Actuator kit" (GM 89018120) which is closer to $200 for that part...
