I tied running the car in open loop but it still did the same thing at idle so I'm guessing the o2. Is good? I'm really thinking its the iac. I may have just bought a bad replacement being used.

I took the iac out and turned the key to on and the isc resets itself like normal but could it still be bad even though I get a response from it. Also when tryin the sas test in evoscan, the isc does absolutely nothing for the idle. And any changes to the iac stepper table does nothing. Neither the iac vs coolant temp tables.

 

When was the last time you checked your plugs? What kind of plugs are you running? And have you checked your fuel pressure?? Try swapping a set of brand new plugs and see if it improves.

 

Yea just changed the plus recently. Definitely not the issue though.

 

Following the thread forsure. Have same problem.

 

Have you tried replacing your iac?

 

Do you think it will help if i changed the IAC? I thought maybe the TB senor. I Just don't feel like spending $300-400 on a IAC And it wont fix it. What do you recommend?

 

I have a spare, used IAC for sale if you're interested. Just need to get it back from the person that borrowed it.

That said, you might want to check this thread beforehand, especially the more recent pages. Domyz and Jamie @ Dynotech are discovering more and more how the idle system works: https://www.evolutionm.net/forums/ec...ssembly-8.html

 

hey just bought an 04 evo 8 with this same issue. I've searched tons of threads and haven't ran into anything similar but yours. Rough cold starts. Like idling at 500 to 700. But when it warms up sometimes it will idle fine at 1k to 900 or sometimes it will still idle at crap like 700 to 800.
mods. Were you able to fix this issue yet?
tomei catback
jd carbon coil packs
hks ssqv bov
Ets intake
AGP 3.5 intercooler
koryo rad radiator

 

the old 03/04 iac's are not that great. try to find a used one from an 05/06. they have a "top hat" style plunger that lasts longer & controls idle better