Hello I'm new to this forum. I'm looking to buy a 2013 Evolution X GSR. While on a test drive in the car I was going on the highway in fourth gear, I floored the car and out of nowhere hit what seemed like a huge fuel cut. On the dash the check engine light came on along with the message "ASC System Service Required". The guy told me this has happened before and that it's caused by overboost, apparently the code is P0234. I did some research behind this, especially on evolutionm, and found no definitive answer to the problem.

The seller is the second owner and he says that the car has a stock tune on it although it does have an AEM cold air intake. With my limited knowledge of turbocharged engines from subaru's, the intake was my first suspect behind the overboost issue. I figured it may need a proper tune for the intake wich can flow more air. The car only has 59,000 miles and is otherwise in perfect condition, appears well maintained, the overboost issue is my main concern. I have no experience with Evo's and was wondering if this is a car I should stay away from? Can this problem be fixed easily with something like a tune? Or could it be major problems? I really love the car and am hoping to figure this out. I appreciate any help.

 

Any other mods? The intake alone shouldn't be a problem. Mine did the same (bought used). Previous owner installed full exhaust (with test pipe) and removed the boost pills (guessing ebc at some point). Flashed it back to stock (tune) before trading it in. Had a over boost issue as well. Fixed the issue with a tune.

Anyway. If you're not sure what to look for... take someone who does. Even if you have to pay. Better safe than sorry.

 

As far as I know the only other mod is some dumb blow off valve and an invidia catback. I read somewhere that the wastegate can be messed with on these cars manually, is that a possibility? The previous owner may have played with the wastegate to get more boost?

 

Start with a visual first. Have you checked the stock cat and bc? Still there? Any other codes?

 

Looked under the car and it appears that the stock testpipe and downpipe are in place, just the invidia catback. No other codes. This seems impossible but there's no way that the bov would be the cause correct?

 

Take a look here for the wastegate. To give an idea. Basically not needed (tune and ebc instead)...

https://www.evolutionm.net/forums/ev...ain-40whp.html

The bov? If anything a cheap one would be leaking and you would drop/lose boost.

Have you checked the boost controller at all? Possible that it was switched out at some point and the pills were removed from the lines.

 

If he flashed it back to stock and is running an intake and a bov I would stay away. Running an intake and bov without being tuned for it is a good way to run to lean and pop something on these.

 

Well I bought the car, it runs perfectly fine until you floor it. This car does not appear to be messed with under the hood, all heat shield are in place around the turbo and aren't bent or anything. I guess I'll have to check the stock BCS. Will someone care to explain the location of this and how to confirm the boost pills are in place?

 

So after some snooping around in the engine bay I discovered this COBB bcs. I'm almost certain this must be my overboost issue. Looks like I'll need a tune. Any idea what damage this could have caused by running without a tune? Will a COBB OTS tune suffice until I get a protune?

 

I'm having the SAME Issue.
I understand that if boost goes over 30psi (I have a 2012 GSR), the code will trip.
A key cycle clears it. Even a momentary spike over 30 will trip it.

So, does anyone know the trick to change the limit before it trips?
There ARE folks making over 30psi I know.
I hear it's an easy fix.

I forgot to add:
I had a 91 GSX. Know very well what fuel cut is. It is the veritable "Hitting a brick wall"
Never had a single one with either Evo. I would imagine the experience would be the same.
On my GSR it's simply "over 30, *Bing*, AYC Service Required...yada yada"
True??

 

I ended up getting a tune, car runs great now. The COBB boost controller I had on there was my problem.

 

So are you still running the COBB 3-port and what is your highest boost?

 

Yes I'm still running it. I'm using a COBB stage 3 tune temporarily until I get protuned in the next few weeks. Peak boost is 22 psi.

 

100% need a tune. You are tripping boost limits. That is what is saving the car right now.

 

Yes I've figured this out. My car was not tuned for the COBB 3 port, it's running fine for now on a COBB ots stage 3 tune.