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That's doing 61mph all the way home (the two high numbers). The twelves are arround town and doing between 65 and 75 on the interstates. I right down the odo at the time of fill up, and then add them to my computer, I am not missing any numbers or slips. On the way home I did wait til over 230 miles to get gas, and the last leg was just over 160miles.
So superduties with a 5.4L motor can get good gas mileage, if you have enough mods.
I have an 05 F250 crewcab,3.73 gears and automatic with the 5.4,it has a little over 7,000 miles on it it gets 14.5 to 15.5 mpg,I have a gibson exhaust and k&n filter.,so you are about average.
The tuner I am using made a big difference, they have the TC lock up earlier and stay locked. I did the factorytech valve body and put royal purple in the Trans at the same time. I am tickled about seeing 19 mpg in a 3/4 ton truck with a gas motor.
I also have a 4" lift and 35" tall tires. Even with those calculations, the speedo was 3mph slower than my GPS showed and it was a 7 hour ride.
I have put 25K miles on my truck since I bought it. I got great mileage twice. 16 & 17!
Most of the time I get 10 to 12, combination of city/highway to and from work. I was so impressed with the truck when I first looked at it, I never noticed, it only has a 4 speed tranny! I'm sure if it had the 5 speed, I would do better.
What brand tuner? I have the 4R100 as do you I am sure. Did it firm everything up in the shifting? Mine is slow to shift most of the time. Like it is almost hesitant to shift cause it might blow up from the mighty power of the 5.4L... LOL
Or, I really needed to change the spark plugs. I just got home from a 800mi round trip to GA and here's my mileages.
So superduties with a 5.4L motor can get good gas mileage, if you have enough mods.
our 1999 with the 5.4 and 373's gets 16-17 all day long on the highway at 65mph. It irritates me cause it gets very slightley less than my 1997 F150 regular cab SB with the 4.6L, also 373's, and it has gobs of power.
our 1999 with the 5.4 and 373's gets 16-17 all day long on the highway at 65mph. It irritates me cause it gets very slightley less than my 1997 F150 regular cab SB with the 4.6L, also 373's, and it has gobs of power.
Forgot ours is a supercab 4x4. I was amazed at how good a mileage this one got when we got it new and is one of the reasons its still around.