hey,
I'm having a really annoying problem with my 2003 evolution 7, its used and shipped from Thailand with 15,000KM.

The problem is that after i drive the car hard/fast with turbo (over 4000RPM) on 15 pounds of boost and i stop, the car's idle goes up and down and dies off sometimes, it either wants fuel or air. sometimes it might stop if i turn the key off and push the clutch peddle, and then continue again

the mechanic said that it was the idle air control valve (IAC), that it was starting to stick when it gets hot, so i paid $300US for a new one and installed it. the car idles perfect, but it still dies off after driving fast and stopping, if i drive the car slow this problem rarely happens. but then why have an evo and drive it slow. The car has no problems driving at all, only when its stops completely.

does anyone know what else could be the problem, please help!
BTW, I'm a total newbie

 

how does it act under regular driving.. or does the rpm dip really low when you stop for a light without letting the car slowly drop rpm before you stop? does your car have and aftermarket intake? A list of modifications might help bring out an idea or 2

 

ok the car drives good, nothing seems to be wrong there, only when stopping.

pic of old IAC valve


Pic of new IAC valve



I just started the car this morning, let it idle for about 3-5 min and the problem started again without driving.

gtg will post more details later from my phone.

 

I have had similar issues with my 04 ever since i put my cams in. You can set the idle higher in the ECU using ECUFlash. I have still had problems though even after idle adjustment on the custom flash. Most stalling issues i have had is when the AC is on.

You can try changing your driving habits, by leaving your car in gear longer so it doesn't just die on you.

I have had greater success using my SAFC II on lo throttle to correct the issue.

 

OK here is exactly what happened, this morning i started the car and let it idle for about 3-5 minutes and the idle started to drop to about 500-600 rpm (as shown in the streaming vid posted above), its usually at 900 or 1100 RPM since i started to actually look it.
Now when the idle started to fluxtuiate, I press the gas peddle and let go, it would rise and maybe go back to normal for 1-2sec and fluxtuiate again, but if I keep my foot on the gas peddle, the fluxtuiation will get worse eventually cut off. this is the first time i'm actually running test on it myself since i'm home and not by a traffic light keeping back a line off traffic.

i'll have to make a new vid with sound using a digital camera or digital video recorder so that you guys will have a perfect understanding off the problem and in turn help me, will be doing that tomorrow since its dark allready.


As far as i know, the car has a
3 inch air piping.
boost controller- low boost 15 pounds
high boost 20 pounds
apex fuel/air controller ( i can probably disconnect that for a test)
6speed gear box (it came with that)
not too sure about the rest, i'll have to ask the prevous owner for the specs on what the car has.


thanks to those who responded so far.

 

Probably the SAFC. I used to have one and my car did the same thing sort of, I removed it and it's fine. I have seen several threads of people complaining about the same issue, and they all had an SAFC as well. Those things are complete ****. Take it off.

 

Hey, thank you very much for the help, will definitely try that since you so strongly recommend it.

any other idea will be greatly welcomed.

 

do you have an aftermarket blow off valve? if so you need to make sure that you are not venting to the atmosphere. it needs to be recirculated into the intake if you are still using the factory ecu. if it is not it will cause the engine to stall when the clutch is depressed and the engine comes down from higher rpms. hope that helps

 

blow off valve spring too soft

 

Hey guys, I read that the coil pack and plugs can also cause the idle to go bad. If anyone can confirm this first hand, it'll be great.

I have an appointment tomorrow with a tune shop to try and solve the problem, hopefully it'll be a simple and not expensive fix, but i really doubt that

Thanks for all your idea's on this problem, and anymore will be greatly welcomed to narrow down the suspects.
I'll be sure to let you guys know the verdict.

 

You might just need a reflash!

 

I really do hope its as simple as that


Just wondering, will a reflash restore to factor setting or change setting, because my evo goes past 260km and does around 290km although I never drive that fast.

 

I used to have a HKS Blow off valve. (circulating to the atmosphere) and it always did that. After building some boost and then stopping to a red light with the clutch engaged the car will always want to go down to 0RPM and stall out.


If you have an aftermarket BOV, try putting back to stock and see if that helps.

 

well there was some oil in the air intake, don't know how that got there. Anyways cleaned that and they did some tests, checked the SAFC, which was set up fine, so that's not the problem, there going to do some more test tomorrow to try and pin point the problem.

The guy said most likely its the Throttle position sensor (TPS) so he will check the voltage level on that and another sensor tomorrow. but since the oil was cleaned out, the car's idle works way better than before.

will give you all an update tomorrow.

PS: I think I have a stock blow off, basically the car was working perfect and then the problem started little by little after a vehicle service.


oh BTW I was thinking about buying EVOSCAN, you guys think this is a good idea?
http://www.limitless.co.nz/evoscan/

 

Boost leak test?
When cold ecu is giving enough fuel to bandaid the un-metered air. When it gets warm it leans out?