My Evo has some mods but nothing crazy. FP RED BB and it has FIC 1150's so idle could be an issue. Lately my car had an EXTREMELY bad idle. I mean it would bounce up and down, far worse then hunt. Stay at 1500 and when it tried to even out and then bounce bounce bounce.

Know what the issue was? Dead battery. That's right. A very poor battery that barely got the car started and would die often. I just put a new one in, perfect idle.

Also guys make sure you put in a DIY Grounding kit, works wonders for idle. Brighter head lights, far less voltage drop on accessories, it just is amazing.


That's all, live and learn.

 

you sure that when you took the battery out and hence reset the ecu it didnt just do an idle relearn procedure and is now fine? not trying to doubt you im just curious because my car idled funny the other night but i think it was just becuase i had the defroster on.

 

Naw I reset it so many times and the same result. Purchased a new battery from AMS and it now works perfectly. My mini battery was going and the new one helped fix it.