Stephen Max

iTrader: (59)

I'm assuming that the SAFC works by adjusting the injector pulse width up or down depending on the correction factor you input at each rpm range.

But doesn't the ECU revert to a pre-programmed injector pulse width for WOT operation? How does the SAFC get around that?

Jer

iTrader: (2)

Not exactly. It reads and changes o2 readings (if set to) before they are dumped into the ECU, thus tricking it into thinking it must add more fuel or less fuel.

It's adjustable by throttle, which helps prevent exactly what you say : the computer "learning" to compensate and negate what changes the AFC inputs : that's why we generally set the thresholds a little higher (around 40%).. changing the "seen" a/f ratio by the ECU at much less % and the ecu will eventually start to lessen the effects of the AFC and basically I guess you could say to start ignoring it.

Anyways, I need sleep. Hope that sorta explains things.

Remember : regardless of whether in closed or open loop (ie. being in or out of WOT), the computer still reads the a/f ratio and makes sure it's within some sort of tolerance. Consider the AFC a multiplication device for that.