Torque Converter?

[Jackpine]

Altitude DOES have an effect, and it actually should improve your gas mileage. The air is less dense so the PCM is going to meter in less fuel to keep the A/F ratio correct. Of course this also give you less power, but once you reach cruise speed, you don't really need much power.

A big consideration, and one that is probably effecting you is the altitude change. Going uphill takes a lot of energy, more than driving on flatland, and you don't get it all back when you come back downhill. That would imply 100% efficiency. So, climbing and descending hurt you more than just cruising on level ground.

Winding roads will keep you in lower gears too, which also hurts mileage. Mountain roads tend to be "twisty".

- Jack

[ticopowell]

Wow, I didnt think altitude would help mileage at all, and yeah hills suck... but the roads arent too twisty, but the speed limit is 45, and on base i dont dare go faster. What I still dont understand is why after cruising back and forth to denver(again 1000ish feet lower than colorado springs) I still get 13mpgs... I would think it would jump to at least 14-15 range, but it was about 13.1 every time i checked... and with the odometer I dont know how accurate it is, but the speedo is about 3 mph fast at 75, so 4%, so should I add 4% to my mileage to get an accurate reading to test mpg's?

[JWBFX4]

Originally Posted by ticopowell

Wow, I didnt think altitude would help mileage at all, and yeah hills suck... but the roads arent too twisty, but the speed limit is 45, and on base i dont dare go faster. What I still dont understand is why after cruising back and forth to denver(again 1000ish feet lower than colorado springs) I still get 13mpgs... I would think it would jump to at least 14-15 range, but it was about 13.1 every time i checked... and with the odometer I dont know how accurate it is, but the speedo is about 3 mph fast at 75, so 4%, so should I add 4% to my mileage to get an accurate reading to test mpg's?

The speedo comes from the factory, about 2 mph fast on these trucks. So I would say its probably correct.

[Jackpine]

Originally Posted by JWBFX4

The speedo comes from the factory, about 2 mph fast on these trucks. So I would say its probably correct.

Right, your speedo is probably reading only about 1% higher than it should be reading, so your miles driven is about 1% off too (it's a linear relationship). Unfortunately, if the speedo is faster than actual, the odometer reading is higher than actual too, so, you're showing 101 miles for every 100 miles driven. This is hardly an earthshaking error, but it means your actual mileage is 1% less.

You go downhill TO Denver, overall, but I recall there's a pretty good climb around Monument I think? In Denver, and at the AF Academy, you're doing city driving. I don't see your mileage as being horribly bad, just not great.

However, some trucks are going to get better mileage than others, due to tire size, tread pattern, inflation pressure, gearing, overall weight and production "differences". You really can't expect to set economy records with a full sized pickup truck. And, I'm suspicious of ANY "high" mileage claims I read about for f150s.

- Jack

[ticopowell]

Yeah that makes sense... The only thing that makes me think is that I was getting about 14 before i got the gryphon put in, now its dropped... and I thought i was supposed to go up... oh well though, cant do much about it til i get my custom tunes in...
Thanks for all the help too!

[Longshot270]

It is really hard to compare people's mpg claims on these forums because most of the time your talking to someone miles away that drive different trucks, different terrain and many other different factors. The two biggest factors I have seen for my truck's mpg are fuel quality and terrain. I can get 20-22 mpg going down one road that has been heavily used and is pretty much smooth as ice until the surface changes to a rougher texture. Then I may go down to 17-19 mpg. Hills and turns also have a similar effect on mileage. These factors compound with engine load/rpm to lower your mileage.