Thread: Car "shuttering" under moderate boost?

Ok to start, I don't have a stable wireless connection where I am located (on vacation in the woods) so I don't have the ability to search the forums at this time. Please forgive me if this question is answered already.


I have a 97 Gtp with 90,000 miles. I bought it with about 80K. While driving out on vacation I noticed something weird with the supercharger. If i'm using moderate boost (2 to 5 bars on the boost meter) for a sustained length of time (such as going up hill or passing another vehicle) the car begins to shutter slightly. If I let off and drop the boost, or if I accelerate harder and increase boost, the shutter goes away. When I had the vehicle serviced before driving on vacation, the mechanic showed me the sound inside the supercharger with the stethascope thing he had. It sounded like a scraping noise. He then compared it to the alternator which sounded much smoother. He said he wasn't sure what the noise was and figured it may be the bearing in the pulley.

I've only lately read that the oil in the supercharger needs to be maintained. I had assumed it was part of the engine oil system. Could this be my problem?


Any help is greatly appreciated!

Thanks for reading.

It doesn't throw any codes. It's like the breaks are being applied and released very quickly every second or so. Maybe a misfire but I will do the oil change and see if that solves anything first.


If I don't plan to own the car for more than 25,000 more miles, do I really need the zzp coupler or will a gm one suffice? I ask this because I don't want to have to wait for the zzp one to ship.


Thanks for your help!