You wouldnt really have to worry about that much. If you have a return style system, the problem solves itself, but even with a returnless system, there isnt THAT much fuel in the lines, you switch to your ethanol tune, and you just run a little rich for a little while until you are running full ethanol. leave it switched until you are back to full gas in your lines.
For the money, I would just put a small volkswagon turbo diesel in the car and then you could run cheap biodiesel, if you are really looking for an alternative to foreign oil, want to save the planet, or just want to save some money over the next 10 years. Ethanol is just putting a bandaid on a broken bone. Ethanol is nothing near the answer to the fuel problem, no matter what we here in the midwest would like you to believe. It is just a football to keep people thinking they are winning the green war and taking money away from the middle-east.
Originally Posted by Danthurs
I guess that'* possible, but there are a lot of wires going in to a PCM, you would need a big switch.
I used to get tunes on a chip with a switch for my race cars. Look into chips.... Like superchips and whatnot, most manufacturers offer ones that can have multiple tunes and you can switch back and forth on the fly.
Really useful for situations where you need to change tunes often, such as racing.
Otherwise, you can just get a programmer with multiple tunes, but that is a little less convenient, since you have shut the car off and spend a couple minutes reflashing between fuels.