ok heres what i got 02f250 7.3 with 136000 miles stock truck
no programer or chips

dose have 2inch lift and 285 75 r16 tires and 3inch airstream exhaust from turbo back

i can only get about 6 to 10 mpg at the best

done filters fuel additive checked all i can think even ford has no idea
has no missfires or any codes at all

i am at a loss any ideas i am up for anything at this point

everyone i talk to is clueless

dose not smoke or leak anything and motor runs great but just horrable on fuel

even for a stock truck

 

I would hope you have a 4" turbo back system not a 3", if you went to a 3" system you went backwards from the factory 3.5"...

Are the up pipes leaking? What are your boost levels and drive pressure levels?

 

sorry yes its 4 inch exhaust

and its 20 pounds of boost

not sure what the drive levels are

i only asked ford the boost level

they keep telling me the truck is 100% ok

but something has to be off or wrong

and there is no leaks of anykind that i can find