Ok guys I a 99 F250 with 4" Lift 315 tires a Hypertech chip and K&N Filter charger kit. I decided to check the MPG today and was suprised to see that its only 13. The computer in the overhead console said that I was getting 18. First off is this normal (I hope not) and what can I do to fix it?

 

The 13 mpg might be normal, it depends on how you drive it. The overhead reading off is normal, your Hypertech is the root cause. When I got home from work tonight the OHC was reading 32.7 mpg, that's with the chip on the highest setting and the resistor cranked down to 5.6k. Electronic gizmo's really whack out the overhead.

 

Putting larger or smaller tires on would screw it up too, wouldn't it? I mean it's calculating your mileage based on an algorithm. Not really measuring fuel consumption directly. So if you change one of the constants in the formula, it would screw it all up. Of course if he all ready told the computer he has larger tires, this would not be the case.

Just a thought.

-Shawn

 

Yep, the tires screw up the reading too, but even with stock tires the programmer will mess it up.