wickedxboi

ive read the directions and it says to use dsm 440s/450s. the reason im asking is because i already have the 390s and dont want to try until somebody can verify it will be ok. could i use a missing link and just lower the injector pulse on idle for the 390s? it says not to use a missing link, but that is for 440s/450s.

filetofit

Yes you can run 390cc injectors but you won't be able to run as much boost. And regardless of injector size, when running the hack you cannot use a missing link, it defeats the purpose of the hack.

What people don't seem to realize is that the VAFC does not control the injector pulsewidth (at least not directly). It reduces the MAP sensor voltage that the ECU "sees" by placing itself in between the MAP sensor and the ECU, but the MAP sensor itself must see the boost so that the VAFC can correct the MAP sensor voltage down by whatever correction you apply. In your case, wild *** guess, maybe -25% correction across the board (maybe -20% at the top end of the RPM range)

CzanSOHC

from what i read...you really can't go under 35% without getting a cell...

filetofit

With a -25% cut in MAP output you'll throw a CEL at anything more than about 5 psi of boost. Actually that brings up a good point, what is the exact MAP voltage at which the ECU throws a CEL. I could screw around with my MAP sensor and try to figure it out but does anyone know exactly? I've brought my MAP sensor output up to 3.0 volts, which corresponds to just a hair more than atmospheric pressure, and not thrown a CEL? Has anyone gone over 3 volts?

wickedxboi

if i cant go below -35%, then my 390s will defeat the purpose of vafc hack if i will still throw a cel. any suggestions? sell the 390s and get 440s?


[Modified by wickedxboi, 5:36 AM 9/5/2002]

zojirushi

get a adjustable fuel pressure regulator. This way u can increase the fuel pressure and lean it out more with the afc. I'm able to run 7 psi of boost on my rc 370's. My settings are -33% across and my idle fuel pressure is 43 with vacume.

wickedxboi

how does raising the fuel pressure allow you to boost more?


[Modified by wickedxboi, 6:18 AM 9/6/2002]

Smashback

Because with increased pressure you will be running more fuel across the board, which will allow you to lower the fuel settings on the AFC more than with stock pressure. He said he's running 43 PSI with vacuum, whereas stock should be around 30 PSI with vacuum.

liam821

im not sure of the voltage..but its about 1 or 2psi of boost before the honda ecu goes CEL.

liam

wickedxboi

how would i go about getting this to work if i wanted to run 7 psi?

zojirushi

i would increase the fuel pressure at idle like a few psi. And use around -34% ->
-36% across the afc. This will allow u to run 7 psi. My settings are -33% across and no cel's at .45 bar.

wickedxboi

what is your fuel pressure set at?

liam821

Yea that works great. Just up the fuel pressure to make up for the smaller injectors and lower the afc.

Thats what we did with my friends b20/vtec turbo, 450cc dsm + 65psi of fuel pressure and the afc set at -35%. (b20 is fuel hungry)

liam

wickedxboi

thanks guys for the info