So I have an 03 Evo 8 that runs well but idles funny. When I first bought this car it wanted to die because the idiot I bought it from put on a timing belt kit wrong and the engine was 1 tooth out of timing! No damage done but since then it has always had a funny idle. Idling at 1000rpm it would bog down to 800/700rpm then come back up or it goes to 1200rpm and back down to 1000rpm. When driving and then coming out of 2nd or 3rd to stop it would 50% of the time bog down to almost stalling then shoot back up to 1200rpm then 800rpm then settle at 1000rpm.

Then I got it tuned by Kaizen online and everything got better besides the idle. It's was a little better but still acting funny.

Since then I've put GSC S2 cams, beehive Spring/Retainers and ARP studs. After that It would run for cold start then die. When trying to start it again it would just die. I adjusted the ICS up to 1100rpm which would let it stay running but then it would die when I came out of gear to stop. So I bumped it up to 1200rpm and now it always stays running.

So current problem is 1200rpm idle which gets stuck at 1500rpm most of the time when driving and coming out of gear to stop. Sometimes it bogs down to 900/800rpm. No CEL light ever.

Things I've tried are MAF cleaner. New BOV. Installed new ETS IC kit and ETS Air intake. Next step is AGR valve removal. Does anyone have any other ideas what it could be and have you ever seen or heard about something like this before? All help is appreciated!

 

good luck my car has had a rough idle for the longest now and would drop down and die sometimes. I tried a lot of things and then ended up changing the idle air control valve, and it solved my problem. I have the GSC S2 cams and beehive springs/retainers as well!

 

Did you get a retune after installing S2?

 

Yes I did.

 

what fuel injectors?

 

Try having someone crank your engine when it won't start and you stand in back sniffing for smell of fuel from muffler. If no fuel smell, then do boost leak test. If you're leaking, at idle, your engine could get air from leak and MAF could be reading zero and not add fuel.

 

ETS IC kit
ETS Air intake
Full GeReddy Titanium exhaust
Walboro 255
FIC 1000
FP Green Turbo
GSC S2 cams
Beehive Springs/Titanium retainers
ARP studs
Tuned by Kaizen tuning through emails

 

@2006EvoIXer I'll give it a try. I think I do smell fuel when I start it up but this thing was rich from day one and still kinda is. I think that's mainly due the AGP bov that the previous owner got which isn't that great. Ever since I installed the cams my boost gauge reads -14 instead of the normal -18. Either way the I'll do a boost leak test to see what I get. Will an exhaust leak cause idle issues?

 

S2 cams will drop your vacuum reading because of overlap. My 9 did the exact same thing (-18 to -14), so that's normal. Exhaust leak won't afftect idle.
Sounds like you need a tuner that can adjust your idle and cruise.

 

Yea I think so. Thanks for all the help.

 

I've been trying to track down this issue myself for some time, car wouldn't idle unless I gave throttle to keep it going but drove just fine even under boost. I would definitely check the cam position sensors and the idle air control valve, maybe even crank positon sensor. Some even say it can be a plugged ocv to the mivec gear but you won't have to worry about that on an 8. Just the other night I found out my exhaust cam is off a tooth on timing so that could've been some of my issue also I just haven't dug into it full out yet.

 

It's likely your idle air control valve