skans789

Hello there, i have a classic WRX and on full throttle between 4000-5000 rpm it seems to cut out and come back again, just keeps and doing it on full throttle, but when it warms up for about 30 mins of driving it aint so bad, and you can reach rev limiter if you take it nice and easy 50% accelartation, has anyone got any idea what it could be? thanks in advance,

duncatr

iTrader: (18)

Sounds like fuel cut caused by over boost.

What boost are you running?
Also what mods do you have?
Have you changed anything recently?

skans789

hello there, car has just got a full turbo back exhaust, and a dump valve, first i thought it could be the dumpvalve, so i changed it but nothing, but what i cant understand is when it gets warm, it virtually stops doing it???

skans789

bttt

W9LTN

iTrader: (1)

i just have a full turbo back system on my classic and boost hits 1 bar then drops to 0.9 bar. Older models i think before 98 hit the fuel cut a 1 bar so that is what you could be experiencing. Newer models hit fuel cut at 1.25 bar which is why it doesn't make a difference for me. I read this in my Impreza book so feel free to correct me if i'm wrong anybody.

W9LTN

iTrader: (1)

1 bar fuel cut is pre 97. check the small pipes coming from the turbo. if it is split or popped off it's sure to overboost. i had this problem once when i was on a blast down to santa pod. the pipe popped off my Bleed Valve. Car would boost then drop then boost then drop continuesly.

duncatr

iTrader: (18)

So you have a dump valve and a full de-cat.

We still need to know what boost you are running - do you have a gauge?
Was the de-cat fitted recently?

Take the above advice and check all vacume lines. After time these become hard and brittle due to the heat.

I have heard that some early classics suffered boost cut from a full de-cat especially in the cold where there is more dense air.
IF and only IF thats the problem there is a small restrictor in the vacume pipe from the actuator - this can be opened up slightly to solve the problem.