Let me see if i can understand what you are saying here.

>I think that fuel cut is based more on injector pulse width
>than manifold pressure, and here is why. most all HRC stage
>2 cars with stock injectors and the rising rate fuel
>pressure regulator hit fuel cut if they hit boost without a
>little black box or a vc-whatever or a missing link. think
>about what the nong term fuel trim is..........zero. the
>fuel pressure under vaccuum and at idle is just like
>factory, so while the ecu is reading the peripherials, it
>detects no need for leaning out the entire fuel map.

So you are saying stock injects, with a map voltage greater than the 4.5 volts, when as soon as it sees boost pressure, the ecu is maxing out the pulse width? (assuming no cut device is on the car)By putting on a cut defenser or ML, that it keeps the ecu from making the injectors run at max pulse width? I guess i just dont understand fully what you are trying to say..


when
>you run boost on it, the ecu uses a fuel map which is "quite
>enriched" past 4250 rpm and is basically a linear
>progression based on rpm and throttle position. the main
>reason i say this is on MuRiX's car............there is no
>fuel cut defense device..............and also no fuel cut
> . it however DOES go into a different fuel map once it
>hits boost, which is "very" evident after 4250 rpm between 0
>and 4 psi (it shoots so much fuel per air that it won't
>burn).

What do you mean by this? Does his car barely run at 0-4 psi?

after 5 psi, the air/fuel mixture gets into a
>burnable range, and the car makes power.

By this, i am assuming that he is running fuel pressure almost the same at 0-4 psi, as it is under vacumm ?


the air/fuel ratio
>seems to be slightly dependent on boost pressure, which
>leads me to beleive that it runs on a static base map in
>boost, and it seems to enter the "danger" zone at about 18+
>psi with this map and 93 octane fuel and 525 cc injectors
>with -25% longe term fuel trim and 63 psi of fuel pressure.
>if the fuel pressure was higher, it would be consistantly
>safe, but the regulator the car is equiped with is non
>adjustable. all I say is if you have relatively large
>injectors, try zeroing out all your adjustment devices, and
>lower your fuel pressure so that it doesn't skyrocket under
>boost, and you jsut may never have fuel cut again. it's
>based on injector pulse width imho.

I have the 315cc injectors in my car, and datalogged it to fine tune. I run an idle fuel pressure of 25 psi. This keeps my short term fuel and long term fuel trims much below the -25%, and closer to the stock fuel map. It stays like this while normal engine vac driving, and part throttle, closed loop, low boost. I was getting around 75psi of fuel at 8 psi of boost. EGT's were good, not over 1575. A/F was around .93-.94 at WOT in 3rd gear. At ANY idle fuel pressure above 25 psi, i would get a too rich CEL. Short term fuel trims were almost pegged at -25%. So was long term. What are your thoughts of this? In your opinion, what is the max boost i can run with these injectors? I'm thinking 12-13psi with over 100 psi of fuel pressure.


>
>A.D.P.
>"...If you do too much, people become dependant. If you do
>to little, people loose hope. If you do it right, people
>won't be sure you've done anything at all."
>bring it on............

13.5 @108 MPH-2.2 60ft(stupid FWD!)
S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential
fuel injection)
My webpage: http://eclipsed4evr.home.comcast.net
-1998 Mitsubishi Eclipse RS-T- "Toy"
-1992 Plymouth Laser Turbo AWD(SOLD)
-2000 Honda CR-V(daily)