Surging in 4th and 5th WOT
 

Hi all, recently brought a WRX with mods, FMIC pink injectors, VF35, decatted, uprated fuel pump and ECUtek remap to 336bhp.
The issue I’m facing is in 4th and 5th the car seems to surge/lunge when wot, if I feather the throttle it drives nice but any more than half I get this problem? I’ve done some bits with no joy, only other thing to note is I’m getting a random misfire codes cylinder 2 and 4 but I’m led to believe this is due to a billet flywheel?
any advice welcomed!

Time to log whats actually happening, boost/fuelling etc.

I’m trying to get SSM working or looking at a dyno/diag run. I’m looking at changing my intake pipe as it’s a silicone Perrin one, when the problem happens I make 1.1bar of boost and the surge happens​​​​​​… first and second ok it sometimes happens in third if going up a steep hill?

Overboosting mate, bad mapping or dodgy boost solenoid, or all those mods make the car too good! :lol1:
The silicone intake pipes are known to collapse on good boost / high suck ... not sure if Perrin do or do not! ( I have a fair few bits of Perrin on my Scooby ).

Could be a simple boost solenoid hose has come off? So too much boost when booted?

Won't be due to a billet flywheel as that would only cause poor starts / pull away, requiring a slightly higher idle or more throttle on pulling away.

Suggest go back / go to a reputable Subaru mapper and get them to look at the surge problem.


Don't expect you to have equipment to log the engine parameters as suggested above so will need a Subaru specialist or auto electrician or similar.

Hi thanks for the reply.
I have changed the boost solenoid and this sorted the low boost I was experiencing at first.

I have read up that with the VF35 and FMIC they are prone to surge, on one of the forums it suggests the intake pipe diameter to large, I changed the intake for a different silicon one and it’s much better.
ill see if I can find the link.

https://www.scoobynet.com/general-te...t-problem.html

here’s the thread and its pretty much the same as what I’m experiencing, I have brought a std intake pipe, just need to fit.