Okay so I was driving the Evo this weekend and I exited the freeway and when I reached the stop sign, I shifted it into neutral and the car stalled. My Evo tends to have slight idle fluctuations, but nothing that big. That whole day I decided to pay close attention to my idle and it was going haywire. It would drop to nearly 400 RPM's and then shoot back up to 800 - 900 RPM's. One time the car quickly shut off and then turned back on again.. I noticed this because the power steering went out for a quick second then came back on. Do I have a boost leak or something?

Mods/Specs:

- Agency Power TI Exhaust
- Mechanical SES Fix
- Titek 3" Downpipe
- Apexi Power Intake
- Apexi Induction Box
- RRE Rally Cat
- Walbro 255LPH Fuel Pump with install kit
- RC 1000cc Injectors
- Sun Auto Hyperforce
- Titek V2 02
- ETS LICP V2 Steel Black
- GM 3-Port Boost Solenoid
- Custom Dyno Tune
- Apexi Turbo Timer Black
- HKS turbo Timer Harness

310WHP/299WTQ on 91 octane.

Another friend of mine also has this problem, but his has never completely stalled.
One of my friends told me that this is completely normal, that I shouldn't worry about it if it was when I had my AC on but I want to be completely sure. Another one of my friends told me it could be a vacuum leak, but I've been keeping my eye on my boost gauge and all of the numbers seem normal.

 

I have the same problem.... when rolling to a stop when I take the car out of gear rpm's drop to 400 then shoot back up to normal. only stalled one time though at an auto x when I exited the course, ac also makes this problem much more consistent. I believe that the problem either lies with my battery because it is about to kick the bucket and low voltage could be the issue or it has something to to with my injen intake

 

I'm having that problem as well. I narrowed it to a few cause. 1 is the IACV (Idle Air Control Valve). It's a unit that's right underneath the throttle body. The 2nd one is the Evap system. I ran a scan it shows an Evap code. However there's so many things included in the Evap, but I'm thinking of changing out the Evaporator Canister to see.

A word of advice. If you guys want to change out the IACV, the unit is year specific do to the turbo that comes with the car. I believe 03-04 are the same, but 05 and 06 requires a different IACV because 05 has the 10.5 cm ehaust, and 06 has the larger turbo. The IACV is almost $400 so it's not cheap.

I have an extra one if anyone is interested. It's off an 05 Evo.

 

thanks for the info, if it was the iacv though wouldn't there be idle issues all the time. this ONLY happens when taking the car out of gear foot off gas the rpm's fall and dip to about 400 for a sec and then go back up to normal the car will idle normal all day long! Thanks for any input!!

 

what rom id? If 9650003, then have you tried adjusting the BISS? In evoscan, set it into sas mode, then adjust the BISS.

On a side note: my car has a slightly weird idle as well. On occcasion, the idle will dip to ~ 600 and pop back up. And this is just idling in the garage... It does this driving as well, when I drop it into nuetral. (on occasion)

 

You're right on that. The IACV has a pin that pops in and out to control the air. If it's broken, the car won't idle and that was what happened to me. However, right now it's like what you're going through. The car won't idle when the engine is cold, but idles fine when warm up. Idle fluctuates between 500 - 800 rpm.

When I scanned it a couple of weeks ago, it show an Evap code error, but right now it doesn't show any error at all. Funny thing is that I didn't change anything out.

It seems like a ROM error like what nonschlont says. Disconnecting the batteries to reset the ecu won't work because I've tried that. Seems like I'll have to get it remapped or something. Wondering if getting the ECU flash will cure the problem and get some extra HP at the same time.

 

Can any one tell me if the problem was solved? Have the same idle issue when shifting into neutral...

 

Just somethin I noticed w/ my car...

not sure if this is gonna help u guys any, but if u cruise it to the stop (in gear) and drop it into nuetral, just before u actually stop, this will become less drastic.

I believe it has to do w/ ISCV steps, and 02 feedback... My iscv steps are fine. I have a WB installed in my car, and if I drop it into nuetral while still going a fair rate of speed, the WB goes rich, then lean, then recovers... Now if I were to drop it into nuetral just as Im about to stop, the WB stays 14.7 ish, and idle holds steadier...

 

I noticed the same...

 

Guys, come on! I'm getting crazy with this! HELP!!! Hate when something is wrong with my EVO 9!!!
I had only boost controller and APS 3" cut back installed and everything was OK. After ~10K km it started to stall...
Now I have Turbosmart BOV, FMIC ETS 4" with 3" piping and Fujita conus air filter - nothing changed - even didn't get worse...

 

Bump. I too want to know the cause of this

 

My evo 8 ('04) does this same thing. I know its not boost leaks because i had it smoke tested and absolutely no leaks. Also my map sensor is unplugged for some reason the previous owner unplugged it would anyone know why?

 

welcome