poor gas milage in flexfuel 07 fyi

Noticed poor gas mileage on my 07 periodically over the last 6 months. Finally tracked it down. Apparently the flex fuel calculations were going screwy. I use a predator hand held for a little bump in power and I pay extra for fuel that does not contain any ethanol. About 2 months ago the avy threw a code for being rich. Cleared it and every thing was fine. Started checking all of the parameters that the diagnostics would show. To make a long story short the computer was figuring the ethanol incorrectly. Every tank it would change, reading between 5% to 30% ethanol. I finally got it into the dealer when reading high. They pulled a sample and found 0% ethanol while the computer thought it was 28%   This causes an excessive amount of fuel to be dumped into the system. Apparently the 07 does not have an ethanol sensor but is calculated mathematically by the computer from several different readings. They reprogrammed the computer with some update to fix it. It is a known problem according to the service tech. My mileage is back up, actually it is the best it has ever been. I hope this helps someone else from banging their head against the wall like me. 

Thanks for the info Mello.

tell us what kind of numbers you were getting before the change and after .....

I have an 08 and sometime my number sucks .... but now that I run with traction control off during dry weather I'm getting about 16-18 .....

It had dropped to as low as 13.7 to 14.1 per tank with DoD. Now it is back up to 16.5 or so without DoD. That is combined mileage and I'm not the lightest foot in town. I'm running on 33" tires and 4.10 gears. A little more tuning and I'll turn the DoD back on to see a little more improvement.

MS03 2500 said:

Thanks for the info Mello.

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x2.....every time I've used E-85 recently I've developed mild hard start issues and switched back. Don't have the option of 0% ethanol here, but the last time I switched back to E-10, my fuel mileage never did full recover. Part of it I'm sure had to do with weather, but something's felt just not right. Just pulled my modules today and shipped them back to Nelson for a reflash. Hope that clears the "problem". Personally, I'm definitely over the E-85 thing and won't use it anymore.....and you're right about the change in the way later models calculate ethanol content.