Engine/Transmission (1998.5 - 2002) fuel mileage

[DSell]

need help from the fuel air guru's.

while driving my 2k 3500 stock ctd in the mountains above 5k ft. my fuel mileage consistantly goes between 20 and 22 mpg. running empty of course.



running in my home state at 1000 ft. the mileage drops to 17. 5 to 18. 2 mpg. lets have some suggestions please.

 

[Mark Baker]

Before the real Gurus jump in, I'll ask the amateur question: any chance the A/C was functioning at the lower altitude?

 

[klenger]

The air is thinner up there.



Could it be different fuel? Winter blend?

 

[Alan Reagan]

Sometimes changes in altitude can result in some interesting changes in fuel mileage. At higher altitudes, the MAP determines there is less dense air to deal with and cuts back on fuel. If you drive reasonably you can achieve higher mileage because the engine is trying to be as efficient as possible. Admittedly, your mileage increase is substantial, so fuel quality may have played into this some.