The trick with AFR for E-85 in that stoich(sp) is 9.99 and gas is 14.7 so you need a wideband that reads limbada(sp) so that you can see if you are rich or lean. Also I beleave you would need a tune like with a DSP cause the car would try to keep looking for 14.7 while cruseing. I think I have all that right. If not Im sure Ill get corrected. Also you would have to go about 30% bigger on your fuel jet.
A gasoline wideband will work just fine. Just ignore the fact that the ture stoich values for E85 are different, and tune to the same AFR you would for gasoline.
Lambda is a universal value to tune from. Regardless of what fuel you decide to run, the Lambda value will be nearly identical, whether it be Gasoline, Ethanol, Methanol, or even mixes of Ethanol/Gasoline.
AFR values are a mathematical function of Lambda multiplied by the stoich value of the fuel used.
Example: Stoich for gasoline = 14.7:1 AFR, or 1.0 Lambda
Because 14.7 x 1.0 = 14.7
A Lambda value of .80 would be: .80 x 14.7 = 11.76 AFR
So, if you make great safe power at .80 Lambda (or 11.76 AFR) on gasoline, you'll most likely make the same great and safe power using E85 at the same lambda value, thus resulting in the same AFR value on a gasoline wideband.
People always get hung up on the "true stoich" values, and think they need to tune to the lower AFR values of E85, when in reality, if you wanted to tune with those values, you'd need a wideband that was set up specifically for E85. Otherwise, using Lambda values is the easiest way to think about it!