Just because its easy doesn't make it correct.
Try running open loop, then you're not at the mercy of your narrow band, but instead the mercy of your wide band.
I've seen rigs from other platforms where they measure the E85 to determine that tanks precise mixture, then adjust fuel for that setting.
IMO, E85 seems like a giant headache for a daily driven vehicle unless you're running a flex fuel system.
Before you ask: I can't see it working. Our CKP system is 3x 18x, 3500 impala (E38 pcm IIRC, flex fuel compatible) seems to only have one CKP signal, and a different firing order.
