mark6

Hi peeps,need some advice,just been out for a country thrash and car suddenly started losing power/holding back at 4000ish revs,got a bit worried and took it easy till i got closer to home but now its really fast.

It only used to boost to about 1.2 bar but now its boosting to 1.5 bar!! and turbo is kicking in really aggressively and i'm loving it.

Does anyone know what could have happened? Can overboosting be caused by a mechanical problem? I do have a knocklink and no det is been picked up so don't know wether to be concerned or not.

Car is a bugeye with full de-cat and remap.

Any advice on what to check?

scoobyDAZZA

you put methanol in by mistake ?

mark6

No just usual optimax,i've since driven it again and it seems that its producing more boost and 1st and 2nd gear can sustain it right through the revs so is really quick, but as you get to 3rd gear and above it can't sustain the boost and pressure drops off so is slower,is this over boost?If it is what can cause this to happen all of a sudden?.

It did have a boost restrictor washer fitted when it was mapped at scoobyclinic by pat,is it possible this has moved out of place?where exactly is the boost restrictor fitted?

Also what else can cause this that i can check?

DYK

mmmm a couple of things it could possibly be if it is overboost related is your ECU/wastegate..when the wastegate is opened,the turbo is still accelerating,so for a moment the boost continues to rise,untill the turbo speed falls.this higher than desired boost is overboost.or your oil pressure T-piece could be clogged with oil,or your restricter needs a larger hole drilling in it.this lets the car boost to a lower level.that can also cause overboost..im not 100% sure what your actual problem is,most likely it is something to do with your restricter/washer you had fitted.and give scooby clinic a call and explain it to em..But i just thought i would give you some ideas as to what could be causing it.

DYK

How Subaru's Factory Boost Control System Works v1[1] 01

mark6

The 'waste gate duty cycle' seems like a possibility,i can't see it being an electronic problem so i'm wondering if the wgdc is stuck on 100% for some reason,i'm wondering what boost pressure would be possibly achievable if you tried to max it?,if it was about 1.5 bar then it points in this direction.

apalmer

iTrader: (8)

my mates turbo did that before kaboooommmmm

duty cylce is mapped in to the ecu, unless its been changed?

Solenoid could be sticking open?

mark6

i thought if the waste gate is stuck open,that would be like having a 100% duty cycle,i'll see if i can check the solenoid,put it in cycle mode connecting the green blocks under steering column,how do you check a waste gate?

mark6

well car has suddenly cured itself,anyone got any sugestions as what could have been causing it??I'm begining to think it could have been the waste gate sticking as for a while i kept thinking it got a bit sluggish after a thrash and as that is a mechanical part it could stick a bit where the solenoid is more electronic switching,it only seemed to do it when it had been thrashed for a bit so it could be a heat issue with it.

Does anyone agree with this or other suggestions??