I have recently had my 94 wrx boost raised from 0.7 bar to 0.85 bar , with a HKS AFR unit fitted to help with the mixture issues. However the car is now overboosting badly in 1st, 2nd and 3rd gears.

I want to put it back to 0.7 bar and noticed when removing the bottom pipe from the boost solenoid ( the one that goes to the MAP sensor on filter ) that there is a brass solex carburettor jet 130 size acting as the restrictor.

Does anyone know if I fit a jet with a smaller hole will the boost pressure go back down ?
Does a smaller restrictor size = less boost on a my 94 car ?
Is fitting a HKS fuel cut defencer an option?

Cheers

lumby
do a search for 'boost pressures and little brass bits' on the search facility.....
I asked a pretty similar question around a few months back,I got some quite knowledgeable answers from some people..

The restrictor in the vent (bottom) pipe should have a 2.0mm bore, smaller means slower boost response and possibly less boost, how was the boost increased ? If a restrictor was fitted into the top pipe of the solenoid (the one that goes to the turbo outlet) then that would cause the problem you describe.

Thanks Bob , as far as i can see there is no restrictor in the top pipe , the restrictor was put in the bottom house and it would not appear to be the original one as it is a carb jet and looks smaller than 2.0mm.

I assume this is what has been put in to create more pressure . Do you think sounds correct ?

cheers

Just the opposite in fact, rstricting the flow through the vent pipe keeps pressure on the actuator which restricts boost, they must have fitted another device or restrictor somwhere and needed to balance the control using the one you describe, that part is an official Subaru one, I'll look up the number and let you know.

Email me off line, posting part numbers has led to them becoming "frozen" in the past

[This message has been edited by Bob Rawle (edited 28 January 2001).]

Bobs thanks for the advice will investigate