Idle Problem

My car normally idles at 1000 rpm...but I first noticed when I turn my air on it drops a little bit, between 500 and 1000...but now i found something new. This happened twice in the past few weeks, when i start my car it starts up normal then drops to about 500 rpm ( happened both times when i was going to back up) then it stalls and when i restart it again it just stalls out, it will do this to or three times then drives like normal... Why???

check to make sure your MAS is plugged in. if this is not plugged in (that is if some mechanic forgot to plug it back in) then it will cause your idle to fluctuate btw 1500-500 rpms then die. the MAS is the computer control unit just after the air filter.

http://files.automotiveforums.com/gallery/watermark.php?file=/503/123894MAS.JPG

You probably need to look at stealth316.com on info for the IAC. When you turn the air on the idle is supposed to INCREASE not decrease. MOst likely your IAC is gunked up or not functioning.

I have this same problem with dropping idle after the ac is on so what exactly is an IAC?

IAC=Idle air control. Its toward the bottom of the throttle body. Check out stealth316.com and it will give you all the info you need on how to test it and/or clean it.

take out your ISC, and clean it, and put it back on. It shouldnt take long, and it seems to have help solve a lot of idling problems.

I had the same problem with my car. I had just gotten it back from the shop and it was doing that the guy at the shop turned a little screw where the air intake meets the engine. It idled a little higher but still kept jumping between 100 - 800 rpm, and stalling. When it stalled most often was after I downshifted coming to a turn and then disengaged the clutch. Does that sound like it could be the same problem?

Ya that sounds the same to me...Howd you fix it?

Im sorry but i dont know/remember what an ISC is either.

Ya that sounds the same to me...Howd you fix it?

I got a complete tune up and it still didn't fix it, I know that my air sensor was plugged in. I read something on another site that said that there is an oxygen sensor in the exaust that regulates the amount of fuel injected for each stroke based on reading the exaust. It can tell by the chemicals in the exaust weather the fuel mixture is to rich or to lean. I don't know if the 3s has it or not or where you would even find it but if the fuel is too lean it can cause the car to idle funny and if you keep driving it with a bad fuel mix it can damage the engine. I don't know if thats your problem but it gave a description that sounded just like it.

I got a complete tune up and it still didn't fix it, I know that my air sensor was plugged in. I read something on another site that said that there is an oxygen sensor in the exaust that regulates the amount of fuel injected for each stroke based on reading the exaust. It can tell by the chemicals in the exaust weather the fuel mixture is to rich or to lean. I don't know if the 3s has it or not or where you would even find it but if the fuel is too lean it can cause the car to idle funny and if you keep driving it with a bad fuel mix it can damage the engine. I don't know if thats your problem but it gave a description that sounded just like it.
Had same problem, car would start fine and run for about 5 min. Till engine warmed up, then whenever i pulled up to a stop sign, the engine would stall. Found the coils in the iac would check good when the engine was cold, but after the engine warmed up, one set of coils would open. Fix was to replace the iac. Just for info, don't just check the coil when the iac is cool, warm iac in oven to get it to operating temp. :banghead:

I had that problem, but I change out my spark plugs and it seemed to have gone away. The only time it drops now is when I am reving the engine but it always return back to normal.

I ended up fixing mine by just getting anew iac...well a used one from someone parting out their car...its been working fine except in the past few weeks its starting to act up again, but weel see what happens