Unless you said otherwise its the IAC valve. The way to check is to pull out the motor its the little black servo on the underside of the throttle body on the UICP side. It should have teeth on it that will spin but if those are gone you need a new one. If its the newer version of the motor you won't be able to see the teeth, but I would bet a sh** load of money this is your problem. Idle air control motors run about 450 from the dealer, or you can pull it out in your drive way buy one off amazon for 118 and put it back in. Just don't drop the screws, but to me this sounds pretty obvious that is your problem. Also gap to .022

 

thanks for the advice man..i was going to check the iac valve the other day the dude that owned the car before i think tried changing it bc he gave me a extra but i dont know if this one is any good. But the other day when i was pressure testing my car i sprayed soapy water around the IAC valve and right where it meets the throttle body there were some very small bubbles forming like densely if that makes sense. Also here are some pics of the sensor on my car the bolts are a ***** to loosin they dont wana turn at all even with wd-40 sprayed on them i dont even think those are the oem bolts. Im just scared im going to strip them, anyways here are some pics of the sensor on the car now and the extra i got if any of you guy could tell me the condition if its good or not id appreciate it

 

haha well that sucks, oem bolts are brass and don't rust. To check it see where those 4 teeth mesh on the front in the third and fifth picture, mine I could unscrew that and pull it out and there was about a mm of tooth left, so that would be the culprit. see if you can unscrew/pull out the servo and it should be pretty apparent if thats the cause (not sure if this model of IAC you can -- there are two different IAC's an evo can come with.)

 

alright so just twist the servo untill its loose? and is there any what to tell if this is for my year evo? i try to untwist it now and get some pics

 

i tried turning it that thing doesnt want turn for **** in either direction, is there a special way to do it?

 

I have been reading about this to see if maybe this could be my issues as well. I think I will pull it this weekend and test the voltage. Found a few pictures i really don't want to dump 300 bucks on a part if I am not sure that will solve my issue. I don't stall but idle is super rough when the car sits. My AFR's sweep from lean to rich


Pulled these pics from another thread. This isn't mine.

 

TRY THIS Just get off your cam gears cover and see your timing... maybe on a start, the timing get off by a theet.... that what happen to me... check this first can help you off throw money in the air for nothing

 

ya heres what mine looked like, its only 118 bucks on amazon, so still not like spending nothing but just saying. Hopefully you can see, but my servo just unscrewed easily and all the teeth on it are just worn to sh**

Edit
ok actually it wont let me upload pictures so heres a link to a thread that i started.

 

https://www.evolutionm.net/forums/ev...rol-motor.html

 

Ok So I replaced my IAC. found a uesd one. Is there something more i need to do? I disconnected the battery fired it up and it idlees high now. Start out at about 1700 rpms then it will settle down to 1200 but just can't find the sweet spot. it was late last night so didn't test my old one going to do that tonight. I just cant' my damn car to idle right. Any other help would be great.

 

Anyone?

 

Adjust the biss screw, turn it in I'm pretty sure. Also you said you unplugged the battery but, I would do that for like a solid 5 minutes to make sure its completly reset

 

Yeah, but you need to put evoscan in the mode to adjust the BISS, you can't just turn it or it will continuously adjust in the background like a o2 sensor trim does.

It's called "Speed Adj. Screw Mode" I think

People also say with those different cams, it helps to bump idle timing up 2-3 degrees, usually they have 272 though

 

yah not sure I want to touch the bias screw made my life a nightmare on my dsm I will let the battery sit for a bit longer I drove it about 100 miles today its my daily commute I have mild cams 269s so idk just want it to start idling a bit nicer lmk is anyone has any other suggestions I have a tatrix cable and evo scan so can get into the ecu

 

I tested My IAC Valve with a volt meter. Seems to be with in teh parameters of a working uint. was reading .30 on all pins.. So from what I read that is ok. I am going to see if cleaning it helps also would my MAF cause an erratic idle? Was thinking it might be dirty.