Thread: E85 afr

Originally Posted by dbcruzr

What will changing the master stoich do for me?

The ECU uses the Master Stoich value for all fuel reference tables I believe (PE tables may be excluded). Setting the master stoich to 9.85 will be your new ECU target for AFRs at all times when you're not in PE mode. If you change that stoich value, make sure you also check and recheck your PE tables to make sure you don't have too large of adders vs. throttle position. This could make your new target AFRs actually HIGHER than stoich. once you get into PE mode. Let us know if you need clarification before/after you change your PE tables. I have played with these enough to know them like the back of my hand

set your base PE AFR to anywhere between 7 and 7.5ish to start. then I would make your adder vs. throttle position something around 1 to 1.5 for throttle positions up through 40% or so (then drop off the adder to 0 for all throttle positions higher than that). My PE table kicks in around 28% throttle (when I start building boost). That way, you'll be targeting AFRs around 8.5 to 9 when you get into PE mode, and once you get to 50% throttle or more, you can go to your base PE targets (7 to 7.5). If you aren't running too much boost or seeing knock, feel free to increase that adder out to a higher throttle position (maybe around 60% or even higher). E85 is more forgiving and your intercooling effects are helpful in this case so you can likely stay "less rich" further out into your throttle position and still be safe.