Poor gas mileage

CARLOS424

MEMBER
2011 FORD EXPEDITION
20,000 MILES

Ford Expedition 2011 Flex Fuel use only unleaded 87 gas mileage in city has decreased from 14mpg to 9 mpg no changes in driving habits. Air Filter has been changed. The Truck has only 20300 miles. Can the flex fuel capability be disabled? Ford Expedition owners 2007 do not have this problem. Is the flex fuel the cause of poor gas mileage?

1 Reply

OBXAUTOMEDIC

MECHANIC
3,711 POSTS

Hi Carlos,

Flexible fuel vehicles (FFVs) are designed to run on gasoline or a blend of up to 85% ethanol (E85). Except for a few engine and fuel system modifications, they are identical to gasoline-only models. FFVs experience no loss in performance when operating on E85. However, since ethanol contains less energy per volume than gasoline, FFVs typically get about 25-30% fewer miles per gallon when fueled with E85.1

You cannot turn this function off, have you tried running 92 octain to see if that helps?

If so I would replace the MAF sensor because when these sensors get off a little due too coking they will not set a code and deliver false reading to the PCM.

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

Cleaning them rarely works.

Please let us know what happens.

Cheers