Hi,
My car has an irregular idle. When I stop, the idle drops to about 200-300 rpms and raises to 1000 rpms erratically. I put it in park and it stops for about two seconds, then goes back. When I let it roll it wants to lunge and when I am at a light, it seems to want to quit. My Camaro starts strong, I changed the fuel pump, fuel filter, spark plugs, vaccuum... I pretty hit everything I thought could've been the problem. The engine doesn't push as strong as it did 3 weeks ago. I am thinking maybe it's the computer...? Anyone had this problem? Thanks for all the help.

Sincerely,
Mick

 

Go to the tech articles and follow the IAC resetting procedure. Might as well take it out and clean it while you're at it.

 

Thanks for the help!
Sorry it took so long to reply... I got really side tracked. But now I am more frustrated than ever.
(It didn't work) I resetted the IAC.
(Didn't clean it, maybe that was my mistake.)
When I reset it, I adjusted the screw on the TB pretty high, but idle was about 500 rpm, so I figured it was ok. I followed procedures and everything, and even found other articles on resetting the idle. When test drove the car, about 20 minutes later, the idle started jumping up and down as if I never did anything (in the same way as it was before). I pulled the IAC sensor again and started the car. Immediately the car idled at 2000. I loosened the screw, got it down to as far as 1500 before the TB couldn't move any lower. I put the sensor back in and reset the computer. 500 rough rpms once again. Help please!!! The mileage may be higher that I thought before because once it goes past 99,999 miles, it resets to 0, so I don't know how many times it's done that. Please help! I appreciate any advice you have to offer!!!

 

Check the wires in your MAF sensor maybe. It sounds like my problem (broken MAF). Sorry if that's obvious, but thought i'd offer my opinion, and get another post on my record

 

Sounds like a throttle position sensor gone bad, they won't always kick a code either. Did you perchance wash the engine? The TPS can not be gotten wet, if you get it wet throw it away. I did this once...once, my idle was all over the place, the car would try to lunge when stoped at intersections, I had to mash the breaks hard to keep it from getting me into real trouble.


Also, removing the IAC isn't how to set the idle. Try this procedure

Short pins A & B of the diagnostic connector with a jumper
turn the key on but don't start the engine
Wait 30 seconds for the IAC to fully extend
Remove the IAC connector while the key is still on
Remove the jumper between pins A & B, leave the key on
Start the engine
Set minimum air (Idle) to 500-550 RPM in gear (auto trans) 650-700 RPM manual trans in neutral.
Shut down the engine and reconnect the IAC

Remove the Throttle position sensor harness and install a 3 wire jumper between it and the sensor.
Turn the key on and connect a digital DC volt meter to pins A & B of the harness (positive to middle wire B, Negative to top wire A)
Check voltage, should be between .500 and .600 volts.
Loosen the sensor screws and adjust it to obtain this reading, keep the meter hooked up while tightening the screws to make sure it doesn't change.

Start the engine, everything should be ok now.


~M~

 

Hi,
Thanks for your guys' quick replies! I will check the MAF tomorrow morning... I think it was replaced before because it's a Bosch piece now... just in case I will check it out. As for the throttle position sensor... your symptoms match mine also... all the way to the breaking. The codes read fine and everything. I reset it the same method as you mentioned... but I also wanted to remove the IAC because the car is pretty old... I just need to get a hold of a replacement gasket. Thanks for all the help!!! Keep the suggestions coming.

 

Duke,

The original MAF was a Bosch part. There should also be a GM part number on the MAF housing.



I would suggest removing the IAC stepper motor, disassembling the pintle and spring, and cleaning everything. This little bit of dirt is the difference between a stuck IAC and a functional one: