Quote Originally Posted by devo321 View Post
Hey guys, thinking about pulling the trigger on an ethanol sensor for my C7.5. (CREC engine)

Live in Arizona so the E85 where is a somewhat limited so I'm curious about the process of switching back to 91 if need be.

I'm currently running the 034 Stage 1 tune. From my understanding going to E85 is fairly simple and there's tons of calculators to help for this. The 034 tune is for E60-E85 so planning to aim for E70.

My main concern is about returning to 91. Do I need to get the ethanol content all the way to E10, or is there some flexibility? If I fill up with 91, can I just drive carefully until the ethanol content drops, or do I need to drain the tank first? Also, should I switch the tune as soon as I go below E60, or wait until I hit E10?

For those running an E85 setup, how do you handle going back and forth, if you do?

Thanks!
Do it! I'm in AZ too running 034 Stage 2 on a CREC. I haven't added an ethanol sensor but will be curious to see how it works out for you. I've considered E85 also but just haven't pulled the trigger yet. This 034 video shows the process on how to switch from one fuel to another. I'm not sure how low of an ethanol content the fuel needs to get before going back to the 91 tune but that would be a good question for the live chats that 034 does. https://www.youtube.com/watch?v=nYKJi8CSZ7s