I live in houston and used to get 13.5 mpg.
I went to colorado and got 19.
I installed a k&n fipk and my mileage got worse by two miles to the gallon and my idle increased 200 rpm and became eratic.
Even after the superchip installation the idle is erratic and high.
When it gets hot the truck (F150 SC 5.4l) doesn't act right.
Sucking hot air from under the hood is an obvious no no.

 

Geeman, Towing package ... do you have the 3.74 rear end? That would explain your milage?

 

No. 35something. No towing extras. I think its too hot and the air is too thick. Loved that mileage in colorado.

 

Thanks for all the responses. I had a 1998 f-150 2x4 4.6L that I traded in on this one. I was getting about 16-18 mpg in it. I jumped to a 4X4 with a bigger engine. I guess I was used to the previous mpg. DAHHHHHHH????

I also would not trade my truck in for something that gets better mpg. It is worth the extra $$ in fuel cost to drive it, and with the future mods, I will love it even more!!!

 

I have a 02 Screw 5.4 FX4 with 9000 miles and have consistently gotten 11.3 since day 1, in the city, stop and go with AC on. Was hoping for a little better, once the engine had a few miles on it. The bright side, highway mileage with AC on and running 70+ seems to be 16-17.