s-afc/s-afcii set up and tuning guide.

[turbolarry]

After looking around at other Evo sites I found that none had good information on how to set up/tune with an AFC. DSMtuners has a great article that I followed when I was tuning my Eclipse. I contacted the author and asked his permission to edit it and use it as a basis for an Evo tuning guide. He said yes, so here it is;

S-AFC/S-AFCII tuning guide.

Thanks again Kyle for all your help you never knew you gave me.

[ldstang50]

Nice write up Larry. Question though, was this for an AFC-I or AFC-II. I don't remember seeing STFT or LTFT on my S-AFC I. I know about low throttle and high throttle, your NE points and adjustments. So I was wondering where I would pull these STFT's and LTFT's from

[turbolarry]

Short term and long term fuel trim (STFT/LTFT) values will be read from a logger, not the AFC. It's easer for me to think of it as long term and short term memeory. This is a very crude example;
The ECU looks at O2 values and sees that at 1000rpms it's too rich so it takes out 5% of the fuel it is programmed to put in. That's STFT.
It does this for several seconds then learns that at -5% of the normal fuel the O2 readings gives the desired 14.7 AFR, so it consistantly puts in 5% less every time. LTFT
I hope that make a little sense. Keep in mind this only applies to idle and part throttle crusing. Tuning for WOT you look at the timing.

[ldstang50]

Oh ok, thanks Larry that makes sense