Idle low/too high. Accelerates itself

WZR · #1 02-03-2005, 04:50 PM

98 Grand Am GT. When i crank my car, it either idles low, jumping between 400 and 700rpm or idles high at around 2500 or more.. When idling high, it drops to 1200rpm when placed in "drive". It ususally accelerates on it's own causing me to have to ride my brakes. After a few miles I can kill it and turn the key back and it doesn't idle as high. Acceleration is sluggish at times also. I've had to replace the throttle position sensor before, but i don't know if it's the same problem or why it's doing this. Is it another sensor? Also, my brakes are stiff now and sounds like air leaking when pressed hard. Please help!

FormulaLT1 · #2 02-03-2005, 06:33 PM

Could be faulty or carbon funked IAC or a vacuum leak. Welcome to the forum.

John

GTP Dad · #3 02-03-2005, 07:42 PM

Try cleaning or replacing the mass air flow sensor. Such erratic idle can be caused by a maf that is dirty and trying to pull air into the engine. When this happens it introduces more fuel causing the car to search for proper idle speed. You can clean it by spraying the wires with cleaner and letting them dry. Replace the MAF sensor and it should cure the problem.

Hypsi87 · #4 02-03-2005, 07:57 PM

Quote:

Originally Posted by GTP Dad

Try cleaning or replacing the mass air flow sensor. Such erratic idle can be caused by a maf that is dirty and trying to pull air into the engine. When this happens it introduces more fuel causing the car to search for proper idle speed. You can clean it by spraying the wires with cleaner and letting them dry. Replace the MAF sensor and it should cure the problem.

bad idea, thoes wires are EXTREMLY sensitive. Us turbo buick guys that use a translator plus box run a LS1 MAF. well people were wiping them out left and right. The problem was that people were sprying it down to clean it it would mess up the wires. Your not even supposed to go anywhere near the wires.

your MAF does not controll your fuel at idle it's the IAC motor that seats and unseats a plug over an orface. Alot of times carbon and what not will build up around it becaue of your EGR system. try that before anything elese

swalt · #5 02-03-2005, 08:34 PM

Clean the IAC, and if that has no effect, I would suspect your TPS is gone again.

WZR · #6 02-04-2005, 09:56 AM

Thanks! I'll look into that.

~Jordan

john_uhcl · #7 05-10-2006, 07:49 PM

WZR,

Were you successful in getting this fixed? If so, what did the trick?

XavierKaine · #8 08-11-2006, 01:39 PM

I am having similar problems with my 97 Grand Am. Its to the point where I am on the verge of driving it off a cliff. When I start the vehicle I get an incredable surge. The rpm's fly, after a little bit of running on its own sometimes it drops a little but still rather high. I have noticed, if I turn the car off and start it back up it will lower the rpms. Sometimes I have to restart the car like 6 times before it normalizes. But once I begin to drive for a little bit. I am back to square one. I have had the sensor changed about 4 times already. Brakes are worn down to the bone from constant braking. I have had the computer changed. I am frustrated and don't know what to do. The car has seen about three different mechanics. If anyone can help, I would really appreciate it. You can reply to this post or email me at : [email protected]. Thank you!

FormulaLT1 · #9 08-11-2006, 01:43 PM

Welcome to AF XavierKaine, please don't bring back ancient threads. If the subject you are posting on hasn't been addressed in the past two weeks please make a new thread on the topic (and maybe even post a link to a prior link discussing the same topic) and most of us will be more than happy to help you.

John

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