1996 Pontiac Bonneville idle problem

BIGRIG222

MEMBER
1996 PONTIAC BONNEVILLE
6 CYL
2WD
AUTOMATIC
120,000 MILES

The problem is between 2 parts, the car starts fine but when its in idle it revs up and down, but not alot just small up and down on the rpms and shakes the car and is worse when in drive with brake on at idle. Like the whole car shakes. It hasnt died yet but sometimes it seems like it wants to die and seemed worse when I was on a incline with brake on at idle, im wondering if this is a idle air control valve or a throttle position sensor? The auto parts store says it is the TPS but an inspection place said it was idle sensor. Just wondering if he meant the idle air control valve or is it the TPS?

Tuesday, September 9th, 2008 AT 2:42 PM

3 Replies

MERLIN2021

MECHANIC
17,250 POSTS

Could be either one, but the idle air control valve is more likley, or a vacuum leak. Get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody

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Tuesday, September 9th, 2008 AT 4:13 PM

BIGRIG222

MEMBER
2 POSTS

Another problem is it keeps tripping the check engine light that says it is the oxygen sensors, but I have replaced both of them. So could it still be the problem you said?

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Wednesday, September 10th, 2008 AT 9:33 AM

MERLIN2021