i have a 1999 grand prix gtp and i got a problem i cant figure out. First the */c coupler was bad and making noise so i fixed that and it ran good. The next day it started missing and hardly has any boost. So i hooked it to a computer and it said faulty wastegate. Is that the problem or not. Is wastegate the same as bypass valve or is that a seperate piece? I was told take off the */c belt and see if problem still occurs. I did that and it still misses. I Also hear it could be catalytic converter. was told to take out o2 sensor and drive it and see if thats it so guess ill try that 2marro. please tell me somebody knows what the problem is. It also pops up a light that says service engine. i know it needs o2 sensors cause comp. said so but thats not what im worried about. Please help and thanks for reading.

You should probably get that scanned before doing anything else., Misfires will cause the car not to have any boost.

i had it scanned and it says o2 sensors and wastegate bad

Any chance you can post the codes for us? There are MULTIPLE codes for a O2 sensor.

i will wednesday after i go get plugs and wires

also i am hearing a supercharger dont have a wastegate only turbos do. So does my supercharged gtp have one or not. If so where is it. A nd if it dont why does the scanner say its bad

You actually have a boost bypass valve. Why its called a wastegate, I have no idea. My Bonneville has one.

ok thanks mike. After i get the plugs and wires on i will get you the codes it pops up with. Thanks Mike

Ok i got the missing fixed. It was just plugs and wires. my boost is still not correct. Had it scanned and it says bypass valve solenoid. so should i buy just the solenoid or should i buy the valve also? which one goes bad the most?

Put a muli-meter on the solenoid first and check the OHMs.