Hello, I have an 03 evo fully built> i recently got the motor and everything back in and good to go. Until recently My small battery took a poop on me and i had to jump it acouple times. But i figured out that my small battery has a bad connection at the positive terminal. Im in the process of getting a new one.
The day i had to jump it i drove around for about an hour or so and no problems at all. But the battery was messed up so i put the stock one back in.

So now when i start it up it idles fine for about 20 seconds or so and then starts to idle down and stalls. I looked for boost leaks and i changed out my UICP back to stock just to see. I dont have the right tools to get the IAC valve checked to see if it is still working. I know all my vacuum lines are hooked up right. I dont know what else to check and i dont want to go out and buy a new IAC valve just to find out that it isnt it. espacially since it is like 300 bucks. Let me know if you need more information. Thank you

 

I am having the EXACT same problem....My 03 Evo just died on my at a stoplight....I started a thread and everyone pretty much pointed at my IAC as the culprit. I too do not want to shell out $300 + bucks for an IAC if that is not the problem.....

Someone mentioned there are vendors on here that sell IACs cheaper than at a dealer....I'm looking for them now....I'll keep you posted if I find any vendors on here selling them. There is also a guy on here selling a used one for $120 shipped. It has 26k on it.

 

Yeah im coming to teh conclusion that the iac is the problem. Im gonna take it off tonight and clean it and see if it helps. But yeah 300 bucks is freakin stupid.

 

i think your stock battery is not in a good shape..
its 6 years old you know...

 

Are you on stock computer? My evo did the same thing when I disconnected my battery. Sometimes your stock computer just needs to re-learn its fuel trims on idle. Give it a couple of days...

 

Its not the stock battery from the factory just the stock style battery. Its only about a year old and still reads 12.56 volts and starts teh car fine.

 

Yes im still on stock ecu but it has been reflashed. Ive never had this problem before and ive taken the motor out of the car about 4 times in the past 2 years. And it has sat for months while the motor was getting rebuilt. No problems until now. Long story... And ive never had this problem. And it has been a week that it has been doing this.

Things i have checked-
-vacuum hoses ( made sure they were routed right also)
-Intercooler pipes and couplers
-Fuses
-Turned down fuel psi to 38.5
-PCV valve ( old one was clogged, got a new one)
-Cleaned out the IAC valve and inside the iac mounting

 

Im wondering, Is it possible that jumping it off of my other car cause it to maybe screw something up?

 

if it doesn't work out, I suggest you contact this guy (number in auction) he rebuilds iac's and ecu's, mainly for dsms but it should be a similar theory of repairing them, he really knows his stuff

http://cgi.ebay.com/ebaymotors/Mitsu...Q5fAccessories

D.

 

i just recently too had a stalling with my 03 evo. it would just stall whenever i come to a stop and in neutral. i had no leaks or loose belts, i cleaned the maf sensor, etc. i changed the idle control sensor and everything is fine now. i paid around 300 bucks shipped....=\

 

I have the same problem:

Car starts and idles fine but when I come to a stop the revs dip to about 500rpm and somtimes the car even cuts off...

But I think it might have somthing to do with my closed loop function as I somtimes get a
P0125 Error

Any my cruise AFR's are arround 11 when they should be 14.7...

.

 

It might not be what I mentioned. My evo only took a couple of days to re-learn it self. Have u checked all the plugs and maf sensor wires? It can be something real simple thats causing that, or maybe its time you have a reputable shop look at it. Good Luck with it.

 

I dont need a reputable shop to fix my car. I just need the weather to stop being crappy out. and a day off. The car runs fine When i first starts up.

 

Ok everyone, I have some news, some good news. I hooked up the vehicle diagnostics system ( Snap-On Modis) to my car. I started with doing an operational test to see if everything was working okay. Well everything was. There was a test that had to do with the IAC. So i did the IAC check several times just in case and it said it was ok. So i did the check with the engine off and with it on.

Next i went on to the codes. I found that it had a code that said something about o2 heater high bank? I can remember and forgot to write it down before i cleared it. Also dont remember the number of the code. Well I cleared that code and the car started right up and kept on running. I let it idle for about 20 minutes to make sure and i also did another IAC check and checked for codes again before i turned it off.

I dont know if this will help or if this is the same problem everyone else is having but i just wanted to let everyone know that this is the outcome of what was going on with my car.

Thanks for all the advise everyone!!

 

Check the basic idle speed.

The old fashioned "idle speed control screw" may be maladjusted.

Check the service manual, if you have one, for the procedure to check the basic idle speed (should be 850rpm).

I had the same problem after cleaning my throttle body, and adjusting the basic idle speed seems to have fixed the problem.

Shawn