DirtyScrew: When you get to this point you have to consider some other questions.

1) What fuel are you using? About 18 months ago, the local stations near my finally switched to ethanol-blended fuels from straight gas. I was closely monitoring my fuel economy at the time and it dropped 1 MPG when they went to E10.

2) How are your mileage computations made? Are you using the factory computer (notoriously inaccurate but usually in the other direction). If using the old fashioned method, are you making sure the tank is filled to the same point at each fillup?

3) Tires/Odometer. You mention a tire upgrade. You and the others are right about the tires losing up to about .5 mpg. My truck (factory 4.10 ratios) gained a little from going to 33 in diameter (from a 31 equiv.) but then lost what it gained due to an aggressive tread tire. But what I wonder is if your odo/speedo is correctly calibrated (I've had several trucks and cars that were off!). Stopwatch yourself over a few measured miles on a straight section of highway. Not only should it take 60 seconds to cover one mile at 60 mph, but the odo should read one mile. If not, you can find a correction factor for your mileage, e.g. if you went 1.1 miles over a measured mile, you would multiply your miles per tank by 1.1 (250 miles indicated X 1.1 = 275 miles actually driven). An error in the other direction will make your MPG seem better so if you went only .9 miles over a measured mile, 250 x .9= 225 miles actually driven. If you get a Gryphon, (or an Edge) you can correct the speed by precisely measuring the tire circumference in millimeters and entering that into the computer for a dead-nuts accurate speedo/odo.

4) Lubricants. Not sure if your truck already has a synthetic gear oil in the axles from the factory. My '05 did. Depending on what viscosity is in there, it may make a noticeable difference going to syn. The t-case or AT won't make any difference. Ford installs a SAE 75/140 grade oil in the later trucks, so there might be some benefit going to a 75W90 synthetic. I'm going to try that myself soon. They put the higher vis oil in to protect against heat when towing, but my truck has a Mag-Hytec cover and a oil temp gauge, so I could get by with it. If you don't tow or haul a lot, a 75W90 syn will be safe.
Part B- Are you using a 5W20 engine oil? There can be a small gain by doing so if you are not.

5) Aerodynamics. I installed a winch and bumper onto my truck. Instant 1 MPG loss when I drive above 65. At low speeds, barely enough loss to note. Consider a tonneau, or at least cover over the last three feet of the bed, right in front of the tailgate. There is a great EPA wind tunnel and MPG test on the web that shows the gains (about 1.5 mpg on some trucks). Sorry, can't find the link to post, but you can Google it.

6) In my testing, the exhaust system is the only thing had had a noticeable effect on fuel economy. Intake systems didn't for the reason mentioned in this study.

http://www.fueleconomy.gov/feg/pdfs/...02_26_2009.pdf

In playing with my Edge/Gryphon, I saw some small gains but anything under 1 mpg is very difficult to quantify and pull out of the "margins for error.". Have been playing with advancing the timing a little in level 1 and 2, or going to Level 3 and retarding the timing to run on regular. All seem to change it upward a little. I haven't verified it, but many report better MPG in Level 3, but you have to run premium, the cost of which negates the gain.

7) Anyway, the faster I go , the worse my MPG. My answer is to go slower when I can. At 55, my truck gets 16-17mpg. At 60-15.5-16.5. At 65- 15-16. At 70, I'm happy to see 15 mpg these days. I'm going to try the tonneau thing for my next highway trip.

 

Michael---your post is not pointless and I appreciate it. What you described is what I am afraid of!!!!!!!!!!!!!!!!!! I'm afraid that no matter what I do I'm gonna get 12-14 mpgs! Only time will tell. The only good thing is that I don't drive it very much...maybe 5 times a month due to shift work and taking the Mrs. car. But I still want better mileage. I know I know.....want in one hand and crap in the other and see which one gets filled up first! HA!----DirtySCREW

 

JimAllen---I'm using regular 87 octane. I try to go to one or two stations and EVEN try to go to the SAME pump. I try to take as many variables out as possible. I try to fill up the same way every time; a couple of clicks past the first or to the next whole dollar amount. I believe ALL gas here has 10% ethanol.

I calculate the old fashion way---MATH. Miles gone (measured by tripometer) divided by gallons used (how many gallons it took to fill up). I will try the 60 second 60 MPH test to see if my odometer/tripometer are accurate. That's a great idea.

Tire upgrade?? If you are referring to BFG All terrains, then yes. Agian these are fairly new so they aren't being replaced for awhile.

Lubricants---Yes I use 5w20 Motorcraft Synblend motor oil (with MC filter). I don't know if ANYTHING else has been changed or not. Some on here advised that Ford puts synthetic gear oil in the diffs. I don't know. I DO know that it will soon have either Amsoil or Royal Purple in the diffs. I also plan to put the trans and transfer case in synthetic as well; even though it may not help out with MPGs...its my peace of mind knowing they are better protected

Aerodynamics---I don't have anything on the front of my truck. I did just Ice my truck (turtle wax Ice) so its a LOT slicker and smoother feeling. That alone should cut through the air better yielding an extra 10 MPGS right???--kidding

Tonneau--I don't have one and don't know if they make one (a soft roll up one) that can be use with a tool box. I'd like to have one that begins at the end of my tool box and goes to the tailgate.

I do plan on getting a Gryphon eventually....after everything else is done---DirtySCREW

 

I think the best way for you to deal with your MPG issue is to accept the fact that you bought a big, heavy, safe truck. It's not designed to get the best fuel mileage, if you wanted that, you should have gotten a ranger with the 4banger, or anything else besides a truck.

I've been tracking my mileage for 2 years now, every single fill up. I always stop at the first "click" and 90+% of my fill ups are done at the station, same pump. My total 2 year average MPG is 13.71. I've had tanks that were as low as 11.92 MPG, and as high as 17.42 MPG.

The vast majority of my driving is around town stuff, and I usually get 12-13 MPG (getting worse now that "winter fuel" is here). Just accept it and you will be a happier man!

I take it you've never heard of the terms, "moment of inertia" or "angular momentum" have you?

- NCSU

 

I run Techron through my tank every oil change and when I run it I get worse MPG. Usually within the next tank or 2 when the Techrons gone I start seeing improvement.

 

IMO fuel mileage is all about your right foot. You can have two identical trucks with identical mods and have a huge varience between average mpg. I can get up to 16 mpg or as low as 12mpg, all depending how I drive and thats not only around town but also highway. If you can watch your RPM's and try to do more coasting around town and feathering the throttle on the highway to avoid downshifting I think you can save a considerable amount of money.

 

I average around 17... cleaned my Maf... looks like I gained more. I'll know in the next day or so when I fill up.

 

... and don't be that guy who has to consistanly mash on the throttle at the change of every green light just come to an abrupt stop at the next red one. Your not going to get anywhere any faster, your just beating everyone else to the red light. Every once in a while its great to hear the pipes sing, but use common sense.

 

I truly believe you will get better mileage with the stock intake. I ultimately went back to the factory induction on my old truck and saw a minute increase in the gas mileage. I do not have the old records in front of me but I calculate by the fill up, not the lie-o-meter . When you are bringing more air into the engine, the PCM is going to increase the fuel until the tables are maxed out (running lean) which doesn't sound like you are running lean, but again more air requires more fuel ergo less mileage.
As for the suspension issue, how the truck rides will affect your gas mileage. It affects the dynamic of the wheel as it rolls along the road. There are some smart engineering cats who can explain it better than me.
Altitude has a lot to do with it too. I see you are in North Carolina, but I don't know what elevation or if you are relatively close to the coast. The ethanol blends will reduce mileage. I believe for you it is a combination of the 4x4 ride height, aggressive tires, air intake, and the added weight of the front diff and axle set up.
I would not wast money on the tonneau. Mythbusters did an episode with 2 identical f150s and drove the tail gate up and down, windows up and down, and AC on and off. They explained the pressure effect that builds up in the bed which actually counteracts some of the drag the truck incurs as it moves through the air. The tonneau cover or tailgate down reduced this effect thereby reducing gas mileage. I didn't read all of your mods, but I would consider reducing some of the parasitic drag by switching to e-fans and maybe under drive pullys. FYI my last fill up netted me avg MPG of 16.13168724279835 MPGs. (392 miles/24.3 gallons).
Some one posted about the right foot. I rarely exceed 2500 rpms when accelerating. It's not as fun to drive, but it is as it is my friend.
Good luck to you.

 

I never go over 2000rpms. At most and this is rare I hit 2000 or 2100

 

It's rare I don't hit 4000+ at least once per trip. Usually when pulling away from a light i'll peak between 2800-3200.

- NCSU

 

Bet it sounds nice. I am more into the low rpms myself. I love cruising. I'll be doing 30 at just below 1k rpms

 

It sounds quite nice http://www.youtube.com/watch?v=Rcgh_EPdgxo

- NCSU

 

Sure does... nifty amp steps too!

 

<--- made it do it!

- NCSU