I'm currently working on maximizing my MPG on E85. The absolute best I've gotten for e85 MPG on the highway (2010 GMC Sierra 4x4x4door, 20 inch rims) has been 12mpg, most averaging 11.5-11.7 highway. I understand I'm driving a pig with probably slightly worse aerodynamic qualities than a refrigerator, but I believe it can be better.
That being said, looking at stock tunes and the Flex Fuel spark, I've been trying to grasp how much, when, and where to add and pull timing at CRUISING speeds- generally .32-.56 loads at 1800rpm at 75. I've also not been able to log any kind of KR to give me an idea that I've gone too far, another e85 challenge. Looking in the repo, it seems the only e85 tunes are for forced induction 5.3's.
I've picked up some MPG with aggressive DFCO, MAF only, some other tricks I did with my 3.5L 4x4 CC Colorado tune years ago to get 25mpg with stock tires. This PCM is just leaps and bounds ahead of the P12s and P10s I'm accustom to. I have only added a CAI, Denso IR plugs, and Taylor Thundervolt wires. The PO supposedly cammed the truck- which it sounds like it- but I have no idea on the cam specs and haven't had a chance to pull a valve cover and degree it for duration and lift numbers to cross at TSP's website for EOIT adjustment. The PO also wrote an abortion of a tune, but that's another story.
I'm not looking for somebody else's tune, just some guidance what to log or how to read the logs to give the engine what it wants as opposed to what I think it needs. Is there maybe a parameter to log and shoot for highest or lowest point that I'm missing? I want to understand what to look for and why, what to do when, and why, the same as I do MAF, VE, etc tuning,