afm????

[sandman]

just had my car on the dyno.......
i have...
Hi flow turbo
manafold
dumppipe
denso high v fuel pump
trying to run 15 psi


Running 20/1 fuel at low rpm to 16/1 high rpm/boost
Adjusting afm tooth by tooth until right

gone about 8 clicks leaner on afm and still have 18 at low revs 16 at high......

Thinking bad afm, if u agree, i know there is more than 1 type availabe through injectronics but which is best?

Does having a JAP IMPORT gt4 185, does this mean the afm is tuned to 101octane???

Hmmmm.

[thechuckster]

tweaking the AFM is not an ideal way to tune for boost. Anyway, it would be the ECU that's tuned for different fuel.

Also - by 20/1 AFR do you mean 20:1? in which case that's lean as buggery and you're actually adding fuel to drop it down to 18:1. If not, what scale is that?

Also, the AFM isn't like the TPS - as the AFM flap moves the resistance goes up and down like a saw-tooth pattern. So changing the spring tension on it may not give you the amount of change you're after.

[sandman]

sorry u right....i got that wrong way, 18.1 at low(lean) and well under 10.1(scale only goes to 10)at high. after doing the previous mods stated the car ran very rich, after installing a permanent fuel gauge, reading 2.3 bar at idle and 3bar at WOT, i took the plate off the afm
and found there was a white liqid paper mark on the spring that did not line up with anything... after speaking to other hp workshops they suggested dyno tunig to reset it
(afm)
hence my problem.....

[sandman]

do u think the afm adjustability is not enough to fix my prob? i have standard inj, i should not need to change ecu.....
stock internals only hiflow, fuel pump and boost....

[thechuckster]

i doubt it - and it's not the right way to get more boost into the motor.

permanent fuel gauge = fuel pressure gauge?

have you setup the fuel press regulator correctly? it should have a wider range of pressure when the motor goes from high manifold vacuum at idle to high manifold pressure at WOT

fwiw: i have a sard regulator with a gauge attached to it and it's at 38psi with pump on and motor not running.

[sandman]

i dont want more boost in the motor necessarily, just the mixtures right at stock now and still rich, i dont have fuel pressure reg, tried one and not necessary, have good presure with stock and definitely not leaning out, i have just gauge so i knew it was ok

[thechuckster]

then what is a "permanent fuel gauge"?

am assuming you are using the stock fuel pressure regulator then?

having a bigger pump is not going to get more fuel into the cylinders - but from factory the 3SGTE does run quite rich when under load.

[sandman]

i beg to differ my friend, if u have more pressure behind the injector ....more fuel will enter under and millisecond creating richer idle, off idle the ecu should control as its told by sensors i.e afm

[thechuckster]

bollocks - what controls the pressure in the rail is the fuel pressure regulator.

[sandman]

yes, but after accel...and back off... rail full and pressure high at inject where leak occurs??

[sandman]

i always think of garden hose and thumb.....?

[thechuckster]

The pump supplies volume, the FPR is a variable restriction at the end of the rail after the injectors and that = plus the injector opening time determines how much fuel makes it into the engine.

That restriction varies according to manifold pressure/vacuum (often referred to Manifold Absolute Pressure or MAP) and the FPR will easily accommodate rapid changes in MAP.

Oddly enough, this variation in rail pressure actually results in a constant pressure differential between fuel at injector nozzle and MAP. This makes the injected fuel quantity solely a function of the injector opening time (and makes it easier to tune an engine).
(cribbed from here)

[sandman]

stand corrected...will re hypothesize....cheers, as to afm?

[thechuckster]

do something about working around the ECU-enforced boost cut and flow limitations of the AFM... like fitting an aftermarket ECU that uses a MAP sensor rather than the AFM.

standard injectors, FPR and pump are obviously able to safely provide fuel up to your desired boost target.