now, my dads got a f250 lariat. got that dumb lie o meter in it that says the mpg im not getting. wondering what its hooked to that it gets the reading from, and how often it is supposed to reset? i took the truck on a 7000 mile trip in 8 days, it went from 13.3mpg to 13.2mpg and i averaged each tank out at 10-11mpg (loaded with 12k behind me) also wondering if it registers the tire size difference that i put in when i did the programmer. i was thinking about setting the tire size to 29" til it changes, then swap to the largest tire it offers and see how long it takes to change.

 

I have never trusted the OTC (lie-o-meter). When my truck was stock, it would show around 20 mpg when it actaully hand calculated around 14. Programmer and chips, when added to the mix, will just make things worse. I use mine for temp and direction only. With my mods it reads around 30 mpg now. I WISH!