2003 GM 3.4 high idle

[Russell]

My sister has a 2003 pontiac grand am. At times the idle is high and it pulls the car. I googled it seems to be a pretty common problem but most say the normal fix of cleaning TB, replace sensors, or IAC don't resolve the problem. One post said check the TPS circuit but nothing else. One said unplugging and replace computer fixed it.

She doesn't live close by so I can't help often, she is looking for another car so it might not matter.

Anyone run into this an know what the fix is?

Thanks Russell

[hauen]

TPS is probably shot. That's been my experience anyway.

[Russell]

Have you seen them have a bad TPS and not have a code?

[anotheridiot]

quickest check is getting some throttle body cleaner and spraying it down. There might be a IAT plugged in the duct you can just pull out and spray in that area safely. Most of the time the outside looks clean, but open the blade and its usually full of carbon crud that might be keeping it open. The next place is the IAC, just a simple coned piston usually that cruds up as well. The computer reads more air, it gives more fuel. Last chance is always the stupid temperature sensor since GM loved using that to control fuel air mixture.

[hauen]

Have you seen them have a bad TPS and not have a code?

Yep, the odd thing is I've only seen that happen with speed density systems and not MAF, beats the hell out of me why.

[anotheridiot]

Yep, the odd thing is I've only seen that happen with speed density systems and not MAF, beats the hell out of me why.

work with this edelbrock system, you turn the "idle" screw and it keeps resetting the TPS to zero.

[min301]

anyone check for a vac leak?

[Russell]

Going to bump this back up to the top. Problem is still going on I have not done any trouble shooting yet. Hoping someone has a magic silver bullet. When I goggle high idea for the 3.4 it comes up often but noone ever reports a fix.

[DanStokes]

Look near the base of the carb for the idle screw. Turn counterclockwise. Problem solved!

(Waddya mean, my knowledge is out of date!!??) (Vacuum leak?)

Dan

[Russell]

Look near the base of the carb for the idle screw. Turn counterclockwise. Problem solved!

(Waddya mean, my knowledge is out of date!!??) (Vacuum leak?)

Dan

Intermediate vacuum leak? Seems like I never have time to look at it when I am there. After we sell the Nissan, might try to bring it home so I can fiddle with it.