I recently purchased a SCT X3 tuner from VMP Tuning for my F-150. I have had it on the MPG tune for around 600 miles and have seen a gas mileage drop instead of increase. Before the tuner was installed I was getting about 14.5 mpg. I am currently getting 13.5 mpg and is still dropping. I could be because of the colder weather but am kind of disappointed I have not seen any increase. Any thoughts???

 

No clue, I have never spent money to try to gain mileage, only power and performance.
Also, can you be sure that 600 miles is enough to get an accurate sample of mileage? Conditions change and as you said, gas is probably switching to a winter blend. Checked your tire pressure too? So many things can be to blame.
Why don't you call vmp and see what they can tell you? Or return the truck to stock and see what happens.

 

I didn't really purchase the tuner for mileage. I purchased it for performance but was hoping to get a little better gas mileage too. I will call up vmp tuning and see what they say tomorrow. Thanks Brian.

 

I don't have first hand experience but I have heard cold weather sucks gas mileage in the 150's and btw wow does that mpg suck man I was debating on a 250 with a 5.4 but they get about 15 hwy and was thinking the 150's got way better