I had some questions about turbolarry's SAFC tuning guide it's on evotuners.net. I was a bit confused on the low throttle settings. Basically do you look at the short term and long term fuel %, for example short term: -4% and long term +15% @ 1k rpm and get a combined total of +11% and then therefore the ECU is correcting to add more fuel so you need to add more fuel in the AFC and then it will get to 0%? Or is the other way around where I need to subtract fuel to get it to 0%?

Also for the hi-throttle tuning is there any risk of engine damage by tuning the entire RPM range to the target o2 voltage of 0.92 ~ 0.94?

 

That's the way I understand it. If your LTFT is in the positive range, you need to add fuel to get it to 0. This should only happen if you have upgraded injectors.

Tuning to .92-.94 is proper, but I've found that just getting the optimum AFR is not always the way to make the most power. You need to pay close attention to your timing, because you may get your AFR's looking perfect, but you may be experiencing knock and pulled timing. I sometimes have to tune to .95-.97 O2s just to get my timing to advance to 20 by 7k rpms. I've also had my O2s look perfect at the track on 21-22psi while my timing wouldn't advance past 12, which meant I was definitely knocking. Once I richened up, I regained my timing advance. Of course, the best way to go about this is to log using wideband O2...

 

Hey thanks man, definitely given me some more insight on datalog tuning.

 

How far in the RPM range should I go for the low-throttle settings?

 

You are supposed to get your LTFTs to 0 at 1k, 2k, and 3k at least. Once you get it to 0 at 3k, then carry that fuel setting across the board.