Frank Bangok

I went to check my Unichip settings yday and they told me that my fuel pressure was too low.
I went to my workshop and they installed a fuel pressure gauge between the filter and the engine.
It showed 30 psi at idle and 35 psi at full throttle, not sure if this with vacuum pipe off, I dont know where this is located but cant remember them seeing them taking any pipe off.

We installed a 2nd hand STI pump, idle again 30 PSI, full throttle 38 PSI.

Went back to Unichip, they could see that this pump was slightly better but still not good enough, engine still running lean.

So the question now is whether the pump is still at fault or whether it could be the fuel pressure regulator as I read that pre/post '97 models operate at a different fuel pressure.

I am driving a '96 WRX with full decat, 1 bar boost and Unichip, 260 HP and 300 Nm.

Since I have to do something to solve the problem I am also considering to change to a parallel fuel rail, would that be of any help?

hope to hear.

Frank
Bangkok

R19KET

How did they know the fuel pressure was low, without having a gauge fitted ?

To test the regulator, clamp the fuel return hose, and see if the pressure increases.

One would assume that if two pumps read the same, it's not pump related, unless you're very unlucky, I would also check the gauge, incase that's reading low.

Did they tell you how lean it was ?


Mark.

Frank Bangok

Good question, Unichip can only measrue that mixture is lean so it has to be pump or regulator or injector, we started with the pump but agree that 2 pumps failing is strange so will have to check regulator next.

R19KET

Did they try increasing the fuelling on the Unichip ?

Maybe the mapping isn't correct ?


Mark.

David_Harden

What's this Frank, Scoobynet vs IWOC?

Frank Bangok

2-0 for Scoobynet sofar...