sunroof and supercharger problems on 99 GTP

the sunroof quite working awhile back. most of the time i try it i can hear it it just click. when it does go up it stops and sounds like its grinding a gear somewhere but it will not go all the way back, just up. then it will go back down and make the same grinding noise. it just does that sometimes, most of the time it will just click and not work at all. if any one knows why it does this i would apperciate the help.

i have a 99 GTP with 109000 miles. i replaced the supercharger somewhere around 100000 miles and the boost gauge will not go all the way up when i punch it, it goes up about 2/3 the way. it always went all the way up even when the old supercharger went bad. the vacum lines are hooked up right, the tourge is right on the bolts, and the bypass valve is adjusted right. just wondered if anyone might know what the problem is.


thanks!!

How does power feel since the supercharger was replaced? I'm assuming you are using the stock 3.8" SC pulley. As long as you are sure the job was done right and the boost valve is OK maybe it is just a problem with the boost indicator. The stock one is not that accurate and not indicative of real boost. For that you'll need an aftermarket boost gauge like an Autometer. The aftermarket gauge is more accurate because it will obtain the boost reading off of engine vacuum and ties into the MAP sensor vacuum lines.

Another suggestion is to hook up an automotive vacuum gauge and see if engine vacuum is in specs.

it seems to me that the power is not as much as it was now that i replaced the supercharger.

it seems to me that the power is not as much as it was now that i replaced the supercharger.

Was the replacement SC new or rebuilt/remanufactured? There are two rotor/impellers that compress the charge and there is a certain internal gear ratio of 2.5:1. Basically, a stock Eaton M90 blower produces around 7.5 psi of boost. The only way to really tell if the boost is not right is to connect an aftermarket boost gauge. It will confirm whether you are truly low on boost which will indicate something is not right with the replacement supercharger internally.

The one that I put on is a rebuilt one from CJ Auto out of one of the Carolinas. How much does a aftermarket boost gauge cost and where can i get one?

The one that I put on is a rebuilt one from CJ Auto out of one of the Carolinas. How much does a aftermarket boost gauge cost and where can i get one?

Rebuild from CJ Auto? Interesting...big question mark on that. :dunno: You may have gotten one setup for another make car running an Eaton M90 Gen3.

The gauges cost anywheres in a range of $35 for just a boost gauge like from Autometer (Phantom) to over $200 for the Aeroforce Intercepter Multi-function scan gauge. We get them from pfyc.com and 3800performance.com.

When the supercharger went out, CJ Auto sent me one that I put on. It was for the wrong model and I had to change it again. The one that I put on the first time wouldnt even register a quarter of the boost. This one does better but like I said it still isnt the same that it used to be. I have the number of the guy so I should call him again. Is there anyway to tell if its the right one so I might get around changing it again.

When the supercharger went out, CJ Auto sent me one that I put on. It was for the wrong model and I had to change it again. The one that I put on the first time wouldnt even register a quarter of the boost. This one does better but like I said it still isnt the same that it used to be. I have the number of the guy so I should call him again. Is there anyway to tell if its the right one so I might get around changing it again.

From the outside probably not. From internally you could check the drive gearing and rotors/impellors. The original GM part number was 12371986 but that doesn't mean anything for parts made by other companies for GM like Eaton. Did you resuse your original pulley or did the replacement come with one. Measure it to see if it is 3.8". Other than that you might consider contacting CJ Auto and explain the situation of the low boost not being right.

the pulley that is on it was sent with the supercharger and its 3.8 inches. thanks for all your help. ill see what i can find out about it.