Idling very high?

HOTLEAD1209

MEMBER
1998 BUICK CENTURY
3.6L
6 CYL
2WD
AUTOMATIC
79,000 MILES

Alright, here you go. I changed the spark plugs and ignition coils. Days later the water pump was changed. Started sputtering so I changed the IAC. Got a code for the #6 valve so, I changed the injector and exhaust manifold gasket, still ran rough, said it was crankshaft so, that got changed and I discover theirs and A and B. I did B. Idled really high coded for MAP, changed it and still same issue. I need this car, it's all I got. Thank you.

4 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,602 POSTS

When this engine idles high it can be a sign of the IAC motor that has stopped working/defective. Here is the location so you can swap it out. Also, please check the engine for vacuum leaks. You can use this guide when the engine is cold only:

https://www.2carpros.com/articles/engine-idles-too-high

and

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Since you have it apart, I would service the throttle body and IAC passages.

https://www.2carpros.com/articles/throttle-actuator-service

Check out the images (below). Please let us know what happens.

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Thursday, March 21st, 2024 AT 6:19 PM

HOTLEAD1209

MEMBER
2 POSTS

I changed it. I said that in the post. Couldn't find a leak. I did all I knew to and checking for leaks is always a must. I tried a reset with the battery cable removed for a hour. Started again, same results. My next move is the throttle body. There is one thing I noticed. After I turn off the car, I hear a large like discharge of air, like a whooshing sound. I believe it may be from removing pulley to do crankshaft there. The pulley moved around some as it was being done. Someone said I could throw out of whack like that. I have 3 code a p0336 and a p0102 and p0102 pending(?) I'll Keep you posted. Thank you.

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Sunday, March 24th, 2024 AT 6:04 AM

KEN L

MASTER CERTIFIED MECHANIC
47,602 POSTS

Can the IAC be defective? Also, the whooshing sound might be because of a partially clogged catalytic converter. This guide can help us check, you might want to loosen the exhaust head pipe and retry it. If this is the case, then the PCM will see the engine as having low vacuum and give the engine more fuel because it thinks it is under load.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please go over this guide and get back to us.

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Sunday, March 24th, 2024 AT 10:52 AM

KEN L