Is there such a thing as boost creep?

Basically, MY96 STi was overboosting and hitting fuel cut. I installed a MBC and set it to 0.9 bar (think it might be 1.0 bar as gauge might be slightly out!) and tonight, it hit 0.9 on the gauge, foot kept planted, the boost slowly crept up until I hit the fuel cut!!!!

Can't understand why this is happening??????

Anybody?????

 

Yep

Pi55ed me off on my old wrx a few years ago.

Soultion? get the wastegate ported so it flows enough to allow target boost to be held.

 

Could be either the wastegate actuator has gone weak (i.e it starts to cloase hence reducing the amount of boost vented off) or you have an air leak somewhere that is acting like a bleed valve.

If your actuator has adjustment (most do on the TD turbo's), try tightening it by 2-3 turns. Although after this you may have to back off the MBC a bit to achieve the same boost.