92 Buick Park Avenue tries to stall at stoplights

dplookin · 06-07-2018, 12:58 PM

92 Park Avenue. When the engine gets really warm, the engine tries to stall at stoplights. I have to throw it into neutral while stopped. The engine RPM drops and raises, drops and raises, etc. I have replaced all sensors in the past. I'm wondering if some fouled spark plugs might cause the problem. I haven't been driving any distance lately.........just to a local store once a week. Maybe Carbon has built up on plugs.......not sure yet until I start pulling them. I hope it is a simple thing like that.
Any Suggestions ?

aleekat · 06-07-2018, 02:23 PM

With the car in park and running. If you step on the brake does the idle change? If it does, suspect brake booster hose or check valve.

dplookin · 06-07-2018, 02:37 PM

Quote:

Originally Posted by aleekat

With the car in park and running. If you step on the brake does the idle change? If it does, suspect brake booster hose or check valve.

I don't think that it is...........with my foot on the brake, the idle goes up and down, up and down. And, this only happens with the engine is really warmed up by driving a few miles. I am thinking about checking the ignition Coils, 3 of them, and check the spark plugs.

Thank you, dplookin

dplookin · 06-08-2018, 08:24 AM

I'm thinking that the problem might be a bad ignition coil. Besides the car trying to stall at stoplights, it has been using too much gasoline. And, the car has to be driven more than just down the street to the grocery store. If I drive 4 miles, I have no problem. If I drive 12 miles, the problem usually starts up. That longer drive gives a Coil time to get warmer so the problem can start. I have some old Coils in the trunk of the car. I will install the old ones today to see what happens. But, I won't drive the car until tomorrow, Saturday, when there is less traffic to deal with. Hoping this solves the problem. dplookin

Tech II · 06-08-2018, 09:27 AM

I doubt it's a coil or ignition related, because you are not complaining about a misfire.......

Could have a vac leak, bad IAC, dirty throttle plate/bore, dirty pintle on the IAC, MAF problem, PCV valve, bad/weaK O2 sensor, etc....

Have you scanned the vehicle for codes?

dplookin · 06-08-2018, 10:33 AM

It might not have gotten to the backfire stage yet. I recently corrected a vacuum leak. I recently replaced the IAC. Have replaced the Oxygen Sensor. MAF problem sounds too scary........hoping it's not that. I just finished installing some old Coils, and I'm going to wait until tomorrow to drive it when there's less traffic on the road. I appreciate your Response.

I did let the engine run for awhile and put it in drive with my foot on the brake pedal, and waiting to see if the idle would drop. It didn't drop. It was steady. If the problem does continue while actually driving it, I may need to do a couple of the things you suggested, Checking PCV. dirty throttle plate...............etc. I need it to be simple due to some health issues and a Lack of Money. Thank you, dplookin

dplookin · 06-08-2018, 02:10 PM

I did clean the throttle body by spraying the proper cleaner into it a few times. I couldn't see inside of it due to a wire mesh at the opening. No, I didn't take the Throttle off the engine.

I did check for Codes. There were no codes. So, all sensors should be working properly. If there was a MAF problem, I would get a Code stating so.

No sure what else to do at his point except to drive the car for awhile this weekend to see if I have solved the problem. dplookin

Tech II · 06-08-2018, 04:02 PM

I pull the throttle body(need new gasket), that way I can thoroughly clean the plate and bore, and also make sure that the IAC passage is clean, and the pintle and mating surface is clean....

And since this only does this when warm,. it's possible something is expanding and creating a vac leak......I would have a can of carb cleaner handy to spray around the engine when it acts up, to see if the carb cleaner creates a change in rpm's......

dplookin · 06-09-2018, 11:34 AM

Thank you for your suggestions...........Presently, I am living in a Hotel, not by choice, and not in a position to obtain a gasket for the throttle body. I did open the end of it and did as much cleaning as possible especially around the butterfly valve....................Now, I will attempt, again, to see if I can find any vacuum leaks..................not sure I will though. dplookin

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