simple queston i hope

ok i have looked but know me i have over looked it. but my friend has a 2000 grand prix gtp i was to say it is. it the supercharged one. the in dash boost gauge is no readying so i went out a got he im auto meter boost gauge. now we followed one tube inside the car. we plugged it up to it and its reading vacum but it will hit 0 and not gain boost. we know the supercharger is makeing boost. do we have it pluged in worng?

how can you be sure the supercharger is boosting? (just curious)

we took the intake off and spun the pulley by hand you can fill it pulling the air in. that he has two of them one one the car and one off and we was playing for the one off the car as well. there is an open port that we fond and it was and plugged it up there as well, and we where getting presser not vacum. i my left have a twin turbo car and he keeps up with me to a point. but the gt models i walk away form with no prob so that is another way as well. but i know turbo's and superchargers are diff but do the same thing in the big pic of things.

Check out the Boost Bypass valve on the supercharger that is towards the throttle body. Also make sure that the vacuum line going to it is not broken or cracked.

Also in that same general area there is a sensor with a vacuum line going to it and it has a single two wire connected plugged to it. Make sure that is all hooked up and check that this vacuum line (which runs to the fuel pressure regulator, then to the bottom of the LIM, and then to the MAP sensor) is all plugged in and looks good. This vacuum line would be the one you need to "T" off of in order to install an aftermarket boost guage.

I have an aftermarket boost gauge on mine. Like tblake said, go over all your vacuum lines carefully and make sure you don't have leaks anywhere. I just got done resolving an EGR problem that has been driving me crazy for the past six months and it was all due to a cracked vacuum line that I didn't catch. You have to look closely.

BTW, to the original poster, if the vacuum line that you tapped into is already running into the car, thats probably for the HVAC system, and if so, you tapped into the wrong one.