Originally Posted by ms372
for all the tuners, when the car is tuned to run on 94 octant does the 10% ethanol affect anything in the code ? or it doesn't really make a big difference?
and what are the main differences between the 94 tune and the 91?
The M3 DME is an adaptive control system tuned or stock. It will always self adapt to the fuel being used in the vehicle. This includes the octane rating and quality of the fuel due to additives such as ethanol. You can vary the fuel used and the DME will adapt in an attempt to make as much power as it can while keeping the motor safe. This is why you see cars that run race gas typically gain power on the dyno without any changes to the tune.