Homemade SAFC!!

[justjuiceit]

I am the king of "budget" set-ups and I wanted an inexpensive fuel controllling device. I saw that people charge up to $200 for an regular a/f ratio meter, when one can be made for about $15. I am basically looking for the wiring schematic of the SAFC or SAFC II, I dont need a fancy display or even all the other bells and whistles. So any electrical gurus, please let us know!

[MikeMurphy]

http://www.apexi-usa.com/produ...g.pdf

scoll down to page 8

[matt4pl]

i believe there is something about one in the faqs or installs on 240sx.org

[bruinbear714]

Are you talking about making your own a/f ratio meter? Or talking about making your own afc?

a/f meter = easy.afc = little more difficult.

[matt4pl]

if you can make your own meter, couldnt you just use a potentometer in-line and use it to adjust outputs? that way you can do on the fly adjusting, but you'd have no memory function. im no comp wiz, but i dunno. might work.

[BoostFab]

Are you talking about making your own a/f ratio meter? Or talking about making your own afc?

a/f meter = easy.afc = little more difficult.

he said: Homemade SAFC!! so that mean--the controller.

this seem like an interesting addition to the to-do list. let's get more info about this.

[huguetpj]

A simple way to explain how the SAFC works is by using an ajustable high impedance amplifier/divider. The ajustable value is controlled electronically and is taken from the high/low throttle vrs rpm tables.

What the SAFC does is change between values (+-%s) by looking at the rpm and throttle position and deciding the correct factor. Changing this factor in the amplifier/divider circuit (don't know the exact working of an electronically controlled circuit of this kind) and thus the signal the ECU sees is modified accordingly.

Then it has some other nifty features like knock sensing (the II does), MAF changeability, MAF average or mirror (for 2 MAF cars) and some other stuff I can't remember.

Ohhh... and when working in Karman mode what it does is read the frequency of the sensor and use a PWM chip to give the ECU a modified signal.

[matt4pl]

afc meter instructions