97 Grand AM GT 2.4 ** Rough Idle [Archive] - GrandAmGT.com Forum

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Bill P.
04-25-2006, 02:33 PM
After using a code reader and some other test I have replaced the Throttel position sensor (per code reader), The O2 sensor (per code reader) and the MAP Sensor, (this did not show up on the code reader but tested bad). I also put in a new set of spark:confused: plugs. No I did lot let all of this occure one at the time, someone else did. I just purchased it, knowing it had some problems. Motor still sounds quite with 120,xxx miles on it. Power on the road is good.

Symptoms. Runs OK on the road. When It starts it will start up fine, idle fast for about 1 min then start to run rough. The idle is a surge type of thing, up and down a few 100 RPM's.

Any help/suggestions appreciated. First time I have tried to get a Quad 4 to run right..

Bill P.

REV13
04-25-2006, 03:38 PM
i got the same car (3.4 though) and ive had the same 'symptom'..dont know wat it is..kinda went away on its own..once in awhile it comes back...no help here, sorry...

..hopefully some of the more experienced members will read this soon...welcome to the site by the way

digitalballz
04-25-2006, 05:44 PM
Idle air control valve maybe. maybe a vacuum leak. could be a number of different things.

Bill P.
05-01-2006, 10:22 AM
Contlinuning to cuss my 97 GA 2.4 for it's rough idle.

Since the prior post I have checked the vaccum lines and found no leaks. I replaced them any way. I removed the EGR valve and cleaned the seat and blew out the exhaust port. I checked the selonoid valve for movement and it was free. Cleaned some of the crud off it. At first it appeared to idle a little better then went back to it's old ways.

I do have my own code reader.
Here is part of what is confusing me: After I bought the car, knowing the check engine light was on when I bought it. Whe I got it home, I put the code reader on it.

I got two codes:
1. P0300 Random/multiple cylinder misfire detected. (now I already knew that at idel problem) It does accelerate good and run well at road speeds. There could be multiple causes for this. I am an old shade tree mechanic and this if the first Pontiac I have ever owned. The learning curve has started (it also has stopped).
2. P0130 02 sensor circuit malflunction band 1 sensor 1. (front sensor). I installed a new 0@ sensor and the code did not reset after running.

Now comes some of the confusion.

A.
It next set code for Engine Coolant Temperature. I found this to the the temp sensor for the computer (or other engine control) not the instrument gauge sensor. After cleaning the plug, it went away and has not reset. (why did it not set when the first two set???)

B.It set code P0123 for Throttle Position Sensor. I replaced the TPS. That did not help. Guess what it set another different code!

C. This new code was for the MAP sensor, P0105. I guess I am a slow learned so I bought a new MAP sensor and installed it. Guess what, it set another code.

D. Back to code P0123 TPS Sensor. After doubting my sanity I went back and put the old TPS back on. After driving it the code did not reset. I put the new one back on and it has not reset yet.

E. Somewhere along the winding, twisting convoluted way it reset the MAP sensor code also. I cleared it and it did not come back.

My son does not think it is the computer. I think it could be. His experience is 35 years newer than mine and I call him on all current electronic problems. Most of the time he comes thru with the correct answer. This time we are both lost. It has NEVER set a code for a bad computer. My thinking is, if the computer is not bad why does it set a variety of new codes and reset some of them after a new part has been installed. Yes, I did go to Auto Zone and had them check it with their code reader (same model as the one I have). They set the same codes my reader was currently setting (So my reader is working corrrectly).

Any pro's out there that have any suggestions. Has anyone else had ANY problem like any of this?

ROUGH IDEL: Problem is ad low idel with foot off the acceleratro. It lis more like a sureg or "lope" than miss (like 1 our of 4 firings). It just gentely shakes you in rythim.