b18cTurbo

does greedy fmu read positive pressure?
i need prof advise on this
thx

greyzone

I believe all FMUs read positive boost...thats by definition what a FMU is...a boost dependant "fuel management unit"

downpipe

check around...somebody wrote a whole essay on this recently...but it does read boost. it uses the stock map sensor...sending a false signal to the ecu to prevent a cel, and using the map sensor reading to determine fuel delivery up to 6 psi by altering injector pulsewidth. i read that after 6psi it doesn't have any more fuel tables and just leaves it maxed out. greddy told me its good to 10psi with an afermarket fuel pump and an adjustable fp regulator. i've been running 10psi on my gsr with no problems...stock fuel pump. (with a slight boost dependant timing retard...)

greyzone

What you're talking about here is GReddy's FCU, not FMU. THat makes me wonder if the question is about the FCU?? How bout it mikvtech, you mean FCU or FMU??

If it's the FCU (Fuel Control Unit) then its GReddy's old version that was black and the newer one which is blue. Both of these devices are hard wired into the ECU. The FMU, of course, has no wiring and is a vacuum/boost dependant fuel pressure regulator similar to the Vortech FMU that is hooked up AFTER the fuel rail on the fuel return line.

So, which is it??? If it's GReddy blue box I can give you all kinds of info on that. Intrerestingly, GReddy swears the fuel map STOP at 6psi, yet several users are reporting success upo to 9 and 10 psi using it for fuel management. GReddy will often only give figures and stats on their products up to "Standard and stock" levels of performance ratings. They are real particualr about being "politically correct" (or maybe its just CYA) and since their stock trubo application is only promoted as being for 6psi they may not report any figures over that, even thought it may very well handle up to 9 or 10.

The stock MAP sensor can handle about 12psi before it fails.


[Modified by greyzone, 6:23 PM 11/18/2001]

downpipe

oops. i didn't even know that greddy made an FMU.

greyzone, have you looked inside the blue box? all is its is a bunch of potentiomiters. i wonder if with the proper schmatics the blue box could be tuned for larger injectors, more boost, etc. the 6psi thing doens't quite make sense to me either. i had dealings with greddy on this because my car was runnign like crap and from the symptoms i was fairly sure it was the blue box. after many phone calls and a few weeks of forgetting, they shipped me a replacement. PROBLEM GONE. at least they were apologetic, and didn't charge me. sometimes i think that these companies withhold information becasue they don't want consumers tinkering with their products. what do you think of my blue box idea?

b18cTurbo

i was talking about the blue box
sorry

greyzone

i'm going on the dyno soon to see if i can get the blue box to work with the vafc up to 12ish lbs boost...probably within the next two weeks.

I wouldnt really wanta try to change the blue box cause its not adjustable at all so it'd be more trouble than its worth. If im gonna modify something at least do it with somethng thats adjustable, like the VAFC.

Sides, i hear greddy is coming out with e-manage, a unit that will do boost dependant fuel management and more for around 300.00, that sounds like a good option.