well another thing to try to since your tryin to figure it out, is double check the clamps around the bov area is, make sure all those clamps are on the flanges nice evenly and snug. If airs escaping around there it could be causing a weird idle...

 

with a multimeter..

 

My throttle body is extreamly clean right now, i took it off about 2 weeks ago to fix the shaft seal on it and when it was off i cleaned the crap out of it!

 

So today i decided to take my high flow cat off and put my test pipe back on. Let me tell you, it is like a night and day difference. With the test pipe on it is about 54675 times worse. It started ok and warmed up ok, but when it warmed up the idle was horrible! So if it idles better with the cat on it makes me think that the EGR valve is deffinitivly the problem. Im going to take it off and clean it along with inpecting all the vac lines from top to bottom and from left to right. After that, if that doesnt fix it then im going to do the egr delete kit!

 

haven't tried anything as of now.....unfortunately i haven't had the time with anything. i have been researching online and reading anything i can find on "rough idle."

the Evo service manual stated that for 'Rough idle' and 'Engine Stalls' to check:

1. the EGR valve is not closed
2. vacuum hose disconnected or damaged
3. malfunction of the PCV valve
4. malfunction of the purge control system

 

I thought it was idling nicely. lol

 

I just put a cometic head gasket and ARP studs in my car and did the 60,000 mile service (waterpump, timingbelt, tensioner )
Now my car DOES EXACTLY WHAT THE OP'S CAR IS DOING!!!!!!!!!!
I boost leak tested and no leaks
new plugs gapped properly

I am still trying to figure it out......

I will post up my cure as soon as I find one.

 

in fact, many possibilities like : Idle air control, Idle speed control, Throttle position sensor, manifold gasket and throttle body shaft seal

and i checked in the EVO service manual too like 19.5PSI did

 

I changed my intake manifold gasket. did not help.

 

I think I'm gonna try a new O2 next hopefully that will do it

 

that's the first thing we do and it doesn't make any change at all.... i had a code for my o2 sensor...

but hope it's work for you

next step, i will change my throttle body shaft seals...

 

well just so you know if your throwing a front 02 sensor code, sometimes it is due to a boost leak...you need to get your hands on a good scanner, and see if the voltage readings of the front 02 sensor are changing or if its stuck on a specific voltage, or if theres no reading at all, thats one of the main jobs of the front 02 sensor, is to give feedback to the ecu to help determine the proper a/f

 

Yeah i did my rear o2 and it had no effect! But that was before i had evoscan. Now if i nedd to check my o2 sensors i just plug in my laptop!

I still am trying to find time to clean my egr. Ill probably be starting it tomorrow or thursday!

 

I really hope its the EGR that would be an easy fix....

 

So lastnight I decided to finally take the EGR valve off. I used a whole bottle of break clean on it and tried to get it as clean as I possibly can. It was very dirty (black exhaust build up) inside as you can imagain. I don't know if mine was more dirty then most because I've never compaired another EVO EGR. (now im thinking I should have took pictures DAMN) I left it off the car last night so it could dry up all the brake clean vapors before I install it again! Fingers crossed!

If this does not work, I am going to disable the EGR in the ECU.

If people are thinking about cleaning their EGR also look at this thread:
https://www.evolutionm.net/forums/ev...-canister.html