bouncy idle

[MOSHO92]

For the last couple of weeks i have been having idle problems.

The problem is: It seems to have trouble finding the correct idle speed after the engine decelerates. It mainly does this after "spirited" acceleration followed by coasting in neutral. The revs will bounce around from 500 (i dont like this because the oil light flickers when it drops this low) to 1300 rpm for about 10 - 15 seconds before smoothing out at the stationary (car stopped) idle speed (950 rpm) even though the car itself is still moving. This makes me think it is the VSS but it could be anything because the computor does not throw any codes.

So what do you all think? VSS, IAB(it never has this problem when the A/C is on, and i know the A/C messes with the IAB), my new Pro-M 75mm MAF, or the TPS. I think that is all the parts that could cause this problem but who knows, i get suprised daily by this car. Thanks in advance.

 

[SHO--ripper]

Did it do this before the new MAF? IF not that might be the problem. Either way check the codes.

 

[MOSHO92]

I did check codes but there were none. I dont recall it doing this before the new MAF...i guess i can check by swapping out the old MAF but it has its own problems. One last thing: I doesnt seem to do this when the engine is still in the warming up phase. This points more towards the IAB right? How can i test the IAB to see if it is working properly?

 

[Chrisssssssss]

Clean the IAB via the procedure on shotimes.com and try that. Also when you are done that reset the idle also with the procedure on shotimes. I think that it may also be MAF related.

Did you reset the idle settings after you installed the new MAF? This may solve your problems.

 

[olympic]

If your cruise works properly then that usually rules out the VSS. My car wouldn't idle properly when I installed my Ford 80mm MAF without the LPM. It did exactly what your car is doing. So I second your idea to swap in a stock MAF to see if that cures it. If so then contact PRO-M.

 

[89 black SHO mtx]

i have to ask 1 question here. did you clear the KAM? if not this could be your problem as the ecm doesn't see it as a new part unless you clear the Keep Alive Memory. try unhooking your battery for at least 5 minutes io recommend 10 just to be sure. if this doesn't help it may be a bad MAF or a sticking IAB. good luck Ken

 

[SHOZ123]

The sole purpose of the IAB is to control idle and engine speed when coasting. Sounds like it is sticking.

 

[MOSHO92]

yes i cleared the comp when installing the new MAF, and i reset the idle afterwards. I will try swapping MAF's and if that doesnt work i'll clean the IAB (man i hate taking that thing off). I will get back with the results, thanks guys.