Finally figured my mileage today. My extended cab 01 SD 4x4 5.4 is getting 10 MPG. If I drive it very nice and keep it under 2grand doing interstate driving it gets 10 mpg!!!! Sometime if I play with it alittle it gets 12 but whats wrong with that??? Anyone have any ideas??? It runs fine and has 80800 miles on it. I have new plugs for it but the old ones are in decent shape.

 

well the superduty is heavier than the f-150. my f-150 was getting only 12-13 mpg stock in the city and 18 mpg on the highway. now i added an intake, tonneau cover and magnaflow exhaust and now im getting 13-14 in town and 21-22 on the highway

 

Problem must be that 5.4, I get 17-18 with my 6.0 turbo PSD...

On a more serious note:
Have you checked tire inflation and alignment, plug gap along with any carbon tracking etc., ignition timing, or any of the usual things looking for a problem? When was your last oil change, air filter cleaning/change? Did you do anything lately like bigger tires? Lot of variables that could account for low economy....

 

The truck is due for an oil change. I run Royal purple 5-20 in it with great luck and change it every 3,000. Plug gap is fine and everything looks in order. It has a K&N FIPK system and a Hooker aerochamber mufflers. Also has 285/75/16 tires.

 

like stated before, check tire pressure and since you have over 80,000 on it, maybe its time for new plugs if you havent done them recently

 

Tire pressure is fine enen though they are about to get replaced. I have plugs for it.

 

what about wires?
fuel filter ever replaced?

 

It has coil on plug. And I am unsure of the filter.

 

Sorry to tell you this but that is pretty much all I ever got out of my 99 f-250 with the 5.4 and 285/75R16 tires. I got 10mpg pretty much always except extended highway trips (500+ miles) I might get up to 12 or 13.

 

Tune it up and check again.

 

I've had mine since new, and it usually get about 14 mpg. Best is 16 mpg. You ain't that far off. So it might need some attention. And besides, it's a 4 x 4 , and that'll take your mpg down. If you can sort thru the condition of your truck, you can make it a little better.

 

I've been keeping track of my fuel consumption carefully over the past 2 months and I am averaging (city and highway) 9 mpg. No heavy lead footing and that sort of thing. Trying to keep it under 2K rpms and that's the best I can get. V10...... not too bad compared to the V8. No doubt the gear swap brought the number down a tad, but still worth the performance gain.

 

BTW...what gears do you have in it?
you might get a little better mileage with the 4.10's rather than the 3.73's since the engine wont have to work as hard

 

I really don't know. I would believe it to be 3.73's because it is pretty much a dog...

 

that 01 should have 3:73 gears. a swap out to 10' or 30's will help performance but not mpg's.

the bad part is both the v8 and v10 get the same numbers city and highway. just that the 5.4 v8 is really a underpower for the super duty. but if you enjoy a gas motor as i did the v10 was the way to fly and if you want any good steady mpg's then a psd is the only way to fly. 10 to 12 is going to be your real world. sorry guy we gas lovers are stuck with living with that fact as hard and cold as it may sound