When I used my truck to commute about the same amount of miles anmd driving I would be between 10-10.8. But yes everytime I need to make the truck get up and move (stop lights/signs) it needs more fuel to do so and gets worse mpgs, but that just makes sense anyways.

 

I get 11.8, lie-o-meter. 11.2, hand calculated. Its half frwy (70 mph) and street between 25 and 40 mph. I would love to just break that 12 mpg. Now my truck has only 7500 mils on it. I am thinking that it still is breaking in. And with some more time and milage I could see 12 mpg. Or is this just foolish thinking.

 

I've yet to see anything above 11.5. I don't expect to see more and I know my DRW is affecting that.

Foolish thinking.....no.....but you would need some good flat highway driving. I did that and was only able to squeak that 11.5. Maybe some other time I'll do better but my 5.4 only got me in the 13's one highway trip so I'm not very optimistic. I'm sure the 14 and 15 mpgs do happen but I bought mine to haul and tow and there is no "egg" under my accelerator pedal so that doesn't help. I have my car for mpgs.

 

Trying to calculate mpg over such a short distance is a waste of time and basically worthless all around. Hand calculate the average of three full tanks.

My truck runs better on 87 pure gas than 87 E10. Any knock that was apparent on E10 disappears with the pure gas. I don't really notice a big difference in mpg. I usually run the E10 in my truck and spend the extra money for pure gas for in the boats and other equipment that doesn't see the daily use the truck does.

 

The slower you get the mass moving on acceleration the better. Over sized tires also add to the resistance. If you can handle the ride, run your tires at max tire pressure. These are just a couple of suggestions that may help some. Search google for "hypermiling" if you want to learn other little tricks to conserve. Another thing to do is to let off the gas as you are approaching a stop. I know a lot of people that go gas-brake-gas-brake. Try foot off sometimes, especially if you know your going to be stopping. It is not all about Pole Position.

 

Krewat - I also noticed the idling thing. This truck guzzles fuel at idle. If I let the truck warm up for 5 minutes in the winter I go from 10.8 down to 10.

To the OP - When I cut my converter off I went driving around and my 10mpg truck suddenly became a 14+ mpg truck in the city. I thought holy crap that converter was leaking and all plugged up. Well, after about 1 fill up it was back down to 10.something. What I think happens is your computer adjusts for its operating conditions, then you go and cut off a converter (or throw higher energy content fuel in the tank) and it runs lean for a while till the computer re-learns its fuel tables. So I think its entirely possible you got some big improvement, I'm just saying try that fuel a couple drive cycles and it should come right back to baseline

To everyone else - has anyone gotten substantial fuel mileage gains off a tuner? If so, which one?

 

I think I already mentioned it, but I'll throw my hat into this one. 5-5.5 stop-and-go on stock 87 octane tune, or Mike's 87 performance tune.

Mike's 93 octane tune, 6.5MPG same conditions, over a 10 full-tank cycle, and a few back-and-forths between the 93 octane and 87. Each time, 87 got me 5-5.5, 93 got me 6.5. At the time, it was worth it, because the difference in MPGs made up for the increase in fuel cost.

Not sure if it's the 93 octane gas being "better", or the tune. I never tried 93 octane on the stock tune, so I can't say.

Otherwise, no tune made a difference on the highway or mixed. I figure that closed-loop with a stoich mix just couldn't get any better than it already was.

The old "rotten egg under the gas pedal" idea holds the most merit

 

First trip in my X. Engine has 91k miles on it. X has 285/75-16 tires. Running 65 psi (D rated) Running 85 octane from Conoco. I got 13.46 mpg calculated (489.8 on 36.38 gals) vs 14.5 on LOM. I was running 70 mph which was about 1975 rpms. I did notice that if I were to drop my speed to 68 mph with rpm's about 1900 that my lie-o-meter (LOM) would climb. I may try a different tune as I am running the SCT stock 85 octane tune (to many expenses right now to get 5-Star tunes). I hope to change the X back to stock 265/75-16 tires since I am more about practicality then appearance.

I head back home on Friday and I will try the 87 octane with the 87 SCT tune.

 

2008 v10 4x4 f350 crew cab, California 87 octane stock tune I have gotten as high as 13 all freeway driving from Northern California to L.A. Southern California. Normal milage is 12.4. Sct tuner with tune from VMP 87 octane milage went to 13 mpg. Switched to 91 octane and Power tune and went to 13.8 mpg.Now doing JBA headers and complete 3 1/2" exhaust with custom cold air intake and Amsoil in engine and differentials. Goal is 14mpg. I believe this is a possibility and higher on freeway only driving. VMP SCT Tunes definately increase in performance and milage. Will post what I get when doing other modifications. Won't go back to 87 octane after my latest milage results. Standard oil premium from now on. A tad more than others, but I think it to be superior. Love the v10. :-)

 

This attained in 200 miles of Florida I-10 "level", strainght line driving at 75 mph with Amsoil 0W-30 engine oil, 3.73 gearing, Michelin tires, 2WD and 87 octane non alcohol gas. Once 10% gasohol became the norm, 14.5 became the standard. (run this route/test several times a year with a pretty full load of people and gear). This approximately offsets the 1.5 mpg increase experienced when switched from 10W-30 petroleum-base Castrol to Amsoil.

In other words, I am back where I started.

Around town mileage has also fallen from around 13.5 to 12.5 or so. Also agree with those that have posted that this engine consumes a lot of fuel at idle.

Engine runs like a Swiss watch though and this is a heavy vehicle. Have had since new and would not trade for anything else out there!

 

[QUOTE=2004TBIRD;13156746]This attained in 200 miles of Florida I-10 "level", strainght line driving at 75 mph with Amsoil 0W-30 engine oil, 3.73 gearing, Michelin tires, 2WD and 87 octane non alcohol gas. Once 10% gasohol became the norm, 14.5 became the standard. (run this route/test several times a year with a pretty full load of people and gear). This approximately offsets the 1.5 mpg increase experienced when switched from 10W-30 petroleum-base Castrol to Amsoil.

In other words, I am back where I started.

Around town mileage has also fallen from around 13.5 to 12.5 or so. Also agree with those that have posted that this engine consumes a lot of fuel at idle.

Engine runs like a Swiss watch though and this is a heavy vehicle. Have had since new and would not trade for anything else out there![/QUOTE

Did you notice any difference with the Amsoil?

 

[quote=ggbiw;13157181]Absolutely. Best I could ever do on this vehicle pre Amsoil was about 14.5. After switchover, approached 16 but could not quite get there.

Similar experiences with T-Bird and wife's Crown Vicky.

Amsoil says to expect a 5-6% mileage increase over petroleum based oil and that seems to be a reasonable claim in my experience.

 

I've been surprised to say this, my super duty V10 got 15.38 once....only ONCE..... When I first bought it. THis is how I generated the conditions:

Running 235/85/16 Tires, max pressure. I could handle ride so I did it. I ran at 65 mph with the engine turning @ 1900 RPMs. Running gear is as follows: Magnaflow Model 140 Muffler, 3.73 gears, V10 4x4 automatic 4R100. I did this driving from Missoula Montana to Great Falls Montana. I kept my foot out of it, and didnt use the cruise control. Its a EC/LB. I held my foot into the throttle just enough to maintain 65, but not upshift.... When I did the calculations I was pleasently surprised as to the mileage.

 

[quote=2004TBIRD;13165065]Thank you for responding. got the Amsoil. Will do exhaust soon.

 

So Amsoil is the best one? Which do I get? I want to break 400k with this truck, yes I know this truck will be a dinosauer by the time it gets there. But if I go back to work in it yes it will have miles racking up like crazy