No hassle with E85 other than upgrading your fuel system to flow enough of it and finding it in your area if that's an issue. Only one station here carries it at the pump. The other issue is the same as with pump gas - consistency. If you fill up in the summer with E85 and it's actually E85 and you get tuned on that pretty aggressively, but then fill up 4 months later and get E60, you're going to have a bad time. The government stipulates that "E85" really only has to be E51 to be labeled as such, and content changes wildly throughout the different seasons.
I believe the only way currently to actively measure (read: guess at) ethanol content in these cars is to use a combination of both HP Tuners and SCT to be able to have the ECU calculate estimated content based on lambda. Obviously this will only work in the 11-12 cars with wide and sensors. A much better solution would be to either not tune aggressively on it, buy good fuel (race gas/ethanol), or go to a standalone management like Holley that will accept input from a flex fuel sensor. The latter being a fairly costly and invasive approach that most people aren't going to be willing to do unless they are building a race car.
I believe the only way currently to actively measure (read: guess at) ethanol content in these cars is to use a combination of both HP Tuners and SCT to be able to have the ECU calculate estimated content based on lambda. Obviously this will only work in the 11-12 cars with wide and sensors. A much better solution would be to either not tune aggressively on it, buy good fuel (race gas/ethanol), or go to a standalone management like Holley that will accept input from a flex fuel sensor. The latter being a fairly costly and invasive approach that most people aren't going to be willing to do unless they are building a race car.
