So i just got a EVO 8 with 40k miles. From what i can tell the only thing that is done to it is catback, intake, #$%^y BOV. No idea if it is even tuned. The Check engine light is on but starts and idels fine until u come to a stop. When u come to a stop the cars idel goes down to like 400 for 4 or 5 SEC then goes back up to 900. The AFR bounces around like crazy also. Running at normal speed it reads 14.5 to 15.7 but when u give it all shes got it goes down to 11 ish. When the idel goes down at a stop it goes up to 17 ish and or flatlines high. Not sure what is wrong with the car, i am located in SW VA and dont know of any good shops around my area. Any help from you guys would be great. O and i havnt messed with the boost but right now it runs 21 pounds.

 

Also when i give it all in high gears 4th and 5th it boost all the way up then it drops down to 15pounds and a loud gush of air can be heard. Kinda like the bov just opens and stays open. IDK. i have not messed with the greddy boost control. it is on high bost about a quarter turn and gain is right in the middle of low and high.

 

Boost leak test sir... It could be a crappy bov

 

ur cruising afr's are good, and being a low 11 during WOT is good as well

 

i'd find the nearest tuner and get a good tune. a boost leak test would be a smart idea too

 

https://www.evolutionm.net/forums/ev...e-problem.html

 

There is also a APEXI box under the hood. Just now noticed it when i was looking around for boost leaks. It is small and silver in color with 3 thick wires running from it.

 

Well stalling when stopping could be due to your so called ****ty bov.is it recirculating back into the intake? If not get one that does.the stock evo 9 one works good.A valve that vents to the atmosphere can cause stalling when stopping.

 

like they said take it to a tuner let them see if there's anything wrong.
Bov might be shot or something else my advice take it asap unless you feel you can find the issue your self.

 

That apexi box sounds like it might be a ground box. Where do those wires hook up too?

I would head over to home depot and purchase the parts needed to make a boost leak test and do one on your car. Also, get rid of that BOV go back to a stock 9 BOV. I have a feeling that the reason why your car is not idleing correctly is because the BOV is most likely not recirculated back into your intake.

Once you take care of those issues the car should run better, but I would still get a tune just to make sure the car is running at its best.

 

Ya one wire runs the the body(ground i take it) one runs to the Throttle body, and one runs through the firewall and then i am not sure. While looking for it under the dash i found a small switch (medal) that says on and off of course but does nothing when i flip it. The bov is not recirculating. I am looking into finding a stock evo 9 bov now and will try that. There is a totaled one at a junk yard here.

 

Sounds like the BOV is VTA (venting to air). I dont think Apex'i makes a recirc kit for the Evo.

Ge a code scanner, download scantech and get a tactrix cable or in the very least go by an automotive store and have them pull the code. At least find out what you're dealing with.

My guess is its a code for a lean condition because of the VTA BOV.

 

Sounds like the BoV is VTA to me. Take a picture of your BoV. When I bought mine it was VTA too and idleing like ****. It would drop to ~400 then knock itself back up to 1300 and repeat that cycle. I flipped the BoV to recirc and got a tune and now it idles steady as can be.

 

Get it tuned ASAP!

 

If the BOV is adjustable like my GReddy one the spring is probably to loose, because the person you brought it off wanted like loud pshh from it. Make that tighter.