low boost

[scoobypat]

Hi all, just wondering why my scoob has low boost. 7psi, its running about 290bhp, its a 93 wrx.. why I ask is my other scoob was running 14psi.. ive got the same ecu and everything else, any ideas

[Mortster]

Checked all the boost pipes?

What's the reading at Idle?

Has someone changed bottom pipe on the 3 port?

[scoobypat]

no boost leeks, -20 on idle. no bottom pipe not changed. - 20 is what other scoob idles at too

[Mortster]

Any faults stored?

[scoobypat]

no. ive even swapped the BCS.s over

[Mortster]

Blow down the pipe the runs to the actuator, if you can blow, the diaphragm inside is gone. Swapped one over for a guy on Surrey at the weekend just gone.

[scoobypat]

will try that

[scoobypat]

done the above test. actuator working fine

[Scott.T]

Boost gauge plumbed into the wrong pipe.
Your reading actuator cracking pressure rather then manifold pressure.

[scoobypat]

Boost gauge plumbed into manifold

[Scott.T]

Originally Posted by scoobypat

Boost gauge plumbed into manifold

Well you won't be getting 290BHP from 7psi.

That's more like a figure generated by 16psi (and even that's if everything is top notch w.r.t MAF, Plug's, Coilpacks, Fuel Pump, Turbo and compression).

[scoobypat]

when it went to surry rolling road last year the print out says 290. but it had good boost then. its just dropped for some reason

[Scott.T]

Probably a knackered MAF then if the CEL hasn't come on.
Sometimes cleaning the MAF with carb cleaner will bring it back temporarily.

[scoobypat]

ok will try that, thanks

[Scott.T]

The early MY92-96 have a tendency to drop the boost target down to protect the car when it spots a MAF fuelling issue. It doesn't normally throw up a CEL either.

If you can boz one from someone else it could be worth a pint........

[steve1200]

I have a maf from my classic, had it removed when daughterboard was fitted, was working fine before that.

if you need to test

[Brad Wrx]

I had this scott if you remember we fitted dawes device to compensate