FMU users

[bmxpunk]

Because of recommendation by our vrg3 I might look into one of thes to supplement my perfect power.
any recommendations?
But the real reason I am asking is we just turboed my friends 2.5 rs and we are gettin like a fuel cut.

This is a bizzare hybrid. It is a dohc 2.5L block and heads wit h2.5 sohc pistons in it. In theory the compression is higher. bad idea for a turbo but I continue: this was swapped into a 94 impreza L using the recalibrated ECU I bought from matt monson.

All turbo components came off of a legacy turbo.

The problem is that at 35oorpm-4000rpm (just like my car hmmmm) his car looses all guts. the fuel pressure never goes above 40 lbs even with a walbro pump and an FMU. Any idea what gives? I am banking on the maf sendor maxing out like mine, though mine isnt reaching the 4.5 volts anymore.

any ideas will help. and yes we triple checked the installation of the FMU.

[vrg3]

How are you measuring fuel pressure?

The MAF sensor has nothing to do with fuel pressure. On this engine, fuel pressure should always be at least 36.3 psi higher than manifold pressure. If the FMU is actually doing something it should be even higher when on boost.

Figure this out. Check the vacuum hose to the fuel pressure regulator. Check the FPR itself. Check the fuel delivery hoses and pipes. Check the wiring to the fuel pump.

[bmxpunk]

We hooked up a fuel pressure gauge, and we shecked all connections to the fpr and the fmu. he did the parrallel fuel mod which t's to the fpr then goes to the fmu.

All wiring is the factory wiring.

I will have him triple check the vaccum lines.

[vrg3]

Where is the gauge hooked up? What kind of gauge is it? Are you just watching it while also watching the boost gauge at the same time?

Checking the factory wiring is probably a good idea. At the very least, measure the voltage across the fuel pump while it's running.

[bmxpunk]

It ended up being the ECU that I bought from Matt Monson.

Do you know what all they did to that matt?

THe thing runs an Na car great!!!!! but it doesnt seem to like the turbo cars very much.

I am gonna retry it on my car 1 more time then its up forsale. Take not anyone building a crazy Na hybrid in an early impreza.

[vrg3]

The ECU was limiting fuel pressure? I don't believe you.

[Legacy777]

Yeah....the ECU isn't limiting fuel pressure.

How exactly did he hook up the parrallel fuel line mod? Can he, or you draw a little diagram in paint or something?

I looked at it, and can understand if it's not done right, you could get some weird pressures.

[bmxpunk]

Vrg3, I dont believe it either. Its a mechanical thing and not electrical at all. Dont ask me. I bought this ecu from Matt that was from one of the JC (?) turbo 1.8's that matt had used in some crazy hybrid head/block thing. I bought it becasue i was hitting my 6000 rpm rev limiter way too easy with my 22t.

It didn't help my car at all, so I took it out and put it in my friends car when it was NA. He loved it. Seemed to pull harder through the whole power band and had a 7200 rev limit (logged a 7140 on my perfect power just revving it while sitting).

We checked EVERYTHING and it is all correct. He thought, we will just try the old ecu. we put it in amd he is pushing 5 psi of boost wit hlots of fuel pressure all the way to redline now. Nothing else was changed.

I could be wrong but his fuel pressure guage is "T'd" on the return line between the injectors and the fpr(which is still on the car just before the FMU.

car runs absolutely fantastic now with the original Ecu, I cant explain it either.