I have an '06 evo, 80k miles.

I've noticed since the weather has been dipping into the 30 degrees that my car doesn't idle properly when starting on a cold start. Normally it would just idle at 1500rpm and then slowly drop to the usual warmedup idle rpm. But now in the cold it goes to 1500rpm and then dips to as low down to 500rpm for a few seconds then bounces back up to 1500rpm, and keeps doing this until warmed up. It seems like it's about to stall. I dont' need to rev at all to keep the car alive, but it just worries me that my car is about to self-destruct.

If it helps i have a SES constantly on, last time i checked it, it was the code for a loose gas cap (p0456 i believe), however it wasn't the gas cap, since I have reset the SES and tightened the gas cap plenty of times. Could this be the problem, if so how do i go about fixing this p01456 problem.

Thank chew

 

That SES light could be your problem. My car when it is cold idles real low in the RPM range when it's cold and with the Wideband hooked up its rich. I do know for a fact that Evo's run rich when they are cold. Are you sure that that is the code for that? It sounds like what your talking about should be an emissions code and I don't think that is the right code

 

I have that problem too, and still having it. It maybe the IACV (Idle Air Control Valve) which cost about $360 at the dealer.

My friend said that it might be the cold start solenoid/valve, but I don't know if the Evo have a cold start solenoid/valve.

 

I believe it was p0456, i'm not near any autozone, but i'll double check it when i have the chance to. $360 for this part seems a bit dickulous, am i losing any gas mileage or damaging my car by driving with the SES light on & having the car with these idle problems?

 

You might want to read this thread:

https://www.evolutionm.net/forums/ec...-searched.html

 

Thanks, but what does that thread mean in English.

 

From what I got out of that, there are settings in the ECU that aren't properly setup when it comes to cold starts, so you have to change those settings in there to prevent the car from going lean until it warms up and allows you to drive it normally

 

Yeap, so if you don't know how to tune an ECU, then it's best that you take it into a dealer.