tephra and I are discussing what's needed for map interpolation for flex fuel. Are different injector scaling values needed for E85 and pump gas?

 

I think you could squeeze both tunes in using really lean numbers for pump gas. I played with it a little bit when I first switched and it looked like it would fit. If they are scaled so 14.7 on the map is stoich on e85, then ~19.2 or so should be pretty close to stoich on pump gas.

I didn't actually do a pump gas tune though, and I think everyone uses the scaling to switch between pump and e85. So being able to vary the scaling might be best, but I think keeping the scaling the same could work.

 

Looking to do it, "right", so interpolation for injector scaling is on the list. Different fuel maps are used as well, correct?

 

That I'm not sure on since I haven't used pump since I switched.. but it's probably better to err on the side of flexibility and have it interpolate both two fuel maps and the two scalings.

The megasquirt flex fuel uses a flat fuel trim adjustment (would be just like having a single fuel map and interpolating the scaling), but I haven't seen any talk from anyone using it.

I'd personally rather have the support there for different fuel maps even if it works decently having the same map. But I'm not doing the coding so I'll love whatever comes out. =)

 

I have to lower my scaling from 860 for 93 to 770 for trims to be right. I tried to make a happy medium with the maps but couldn't get trims close enough. One would be to fat or to lean. At 770 I could get it to run both without any cell codes but on 93 it was fat at mid trim and would put some flames out the pipes every once in a while.

 

Scaling, fuel maps, ignition maps and boost tables (boost/load desired and WG duty) should have us covered pretty good