a 3.4 pontiac motor

[pontiac3.4]

i have a 95 grand prix gtp with 3.4 when you start it,it will idle high then low constantly untill it warms up. I have changed the idle control valve and it still does . Anybody have any ideas

[troy1]

TPS or a vacuum leak. Any SES light?

[richtazz]

I agree with Troy. Your engine is known for an intake vacuum leak that will cause and irradic idle when the engine is cold. The IAC valve varies the amount of air allowed in the engine at idle or part throttle. Normally, a bad IAC will act up all the time, and not go away as the engine warms. As Troy also stated, a faulty TPS will cause idle issues because the computer doesn't know where your foot is on the gas pedal and cannot adjust fuel, timing, etc... to load.

[pontiac3.4]

thanks for the reply its my son inlaws car and i told him the same thing . found the car for 200.00 due to its problem