Thread: 3100 high idle. nothing is helping.

hey guys im new to gm vehicles and just bought a 96 grand prix with the 3100 for a dd. has 105k on it and intake gasket allready done and ran great when i bought it. i dorve it home and everything was fine. when i went to drive it in the morn it had a high idle around 2k and check engine was on. i ran the codes. i got a tps(weak signal i belive) transmission sliping(which was wierd cause the trans was shifting great and not slipping) and speedo was off by 0-1 percent. so i pulled the throttle body, cleaned it and replaces the iacv and tps. still the same high idle. aany help would be great.

I don't think GM has a Idle air sensor like dodge and ford, so it may be your Mass air Flow that is the issue.

if the iac is clean and working, than maybe you have a vacuum leak...
try to hear it.

I had a similar idle problem on my 3.1 Beretta. It's almost certainly a vacuum leak. In my particular instance the scanner said that there's a grommet that can be sucked into the manifold near the throttle body. Can't remember exactly which one, IAC I believe. At any rate, click this link

3.4L and 3.1L V6 Engine Sensor Locations Pictures and Repair Help

The area I'm talking about is labeled 2 for the IAC. You can see the bracket in the picture. I think one bolt holds it in, check that area for vacuum leaks. We fixed mine by cutting the end off a spark plug wire, was a perfect fit for the tube going in there. Ghetto but w/e, it fixed it. You'll probably have to d/c the battery for a minute or so in order for the computer to relearn how to idle.