engineermike
Well-Known Member
Let me give this example, because it's the one most would be interested in. This is the flex fuel table called "borderline spark modifier for flex fuel":
And this is the weighting table, called "multiplier based on fuel type to blend ffv tables for borderline spark":
Basically, it goes through a bunch of calculations to determine borderline spark (where it expects knock). If it learns more than 30% ethanol, it multiplies the factor from the bottom table by the top table and adds that to the borderline spark timing. These are the factory F150 tables.
For a flex fuel mustang, you'd basically set the top table to some number high enough to get the final borderline number "out of the way" (higher than MBT and cylinder pressure timing limits), then set the bottom table to how you want it to add the timing vs ethanol%. I have my basically just "switching on" 8 deg of timing adder at 55% learned. This keeps it on the safe side, rather than trying to eke a little timing out of it at 25% ethanol.
Sponsored
