When e85 is used, the afr on the stock fuel pulse will show lean so stock computer starts adding fuel pulse. The conversion box sees this and adds its fuel pulse offset, so then the stock computer will back off the fuel trims closer to normal. You have to remember in closed loop it is all about the 14.7 afr from the O2 sensors. What I would be curious is how the open loop afrs look. Most cars can run up to 64% total fuel trim before injector is maxxed out. But, you would get a lean bank code long before that. The box just increases the pulse so the factory computer does not have to. There is plenty of injector size to run e85.