Troupe

there are a few on here with the grphyon tunes and it want be to long and ill have some

allen_98f150

When I got my truck I was getting 15 mpg. ( My only upgrade is a K&N air filter) I filled it to a quarter of a tank with 87 octane and ran a whole bottle of seafoam through it, back till the fuel light came on,filled up then cleaned my maf with maf cleaner. I went to 16 mpg on the very next tank. Some people may not recomend running it through that strong,but I've done it for years on different veihicles and all it ever done was increass fuel milage. Some people say it does'nt have upper cylinder lubricates,but it says it right on the can that it does and mechanics say the same. Local autoparts store here at home push Lucas products,but that's because of sales reps.
If you run a K&N air filter I recomend maf cleaner at least once a month because of build up from the oil. The last time I cleaned mine I put a little to much oil on it and actually got a check engine light 'cause of build up on the maf. I cleaned the maf and the code cleared ( stupid me ). Oh yeah I also run at 35psi.

rhicks20

'04 FX4 SC with 2" lift and 20" tires w/3.73 gears. Cold air intake with K&N with airaid throttle spacer. Driving to work and back at around 55-65 mph I get 19-21 mpg all day long. My '02 FX4 before it with similar setup got even more because of 3.55 gears.

rhicks20

Now....on the interstate @ 74 mph I only get around 17-18...cost of headwind.

dieseldan2005

Well what the heck. Sounds like mine isn't do ing so well. I use seafoam all the time and i will try soem today. I have plenty of cans waiting. I will also try cleaning the MAF sensor.

CrashTECH

Just throwing this out there... I did some math...

Increasing your MPG by ~ 3mpg will reduce your cost per mile (fuel only) by ~ $0.03. To make back the $430 (call it $450) you would have to sustain that gain over 15k miles to break even.

Doing this mod for milage increases alone is only going to be valuable only in the REALLY long term. If you can get 5 mpg more, you can recover $700 in about the same time period.

However if you get 5 more MPG for $300, you recover it in 6500 miles

Just some food for thought.

BigRedXlt

I am sorry but I have trouble believing that you get that kind of mileage in a SC just a CAI and a throttle body spacer.

CrashTECH

I saw 19.1 mpg mixed highway country when I drove out to my mom's house to bike up my CBR a few weeks ago. Unmodded 04 FX4 screw with the 5.4L.... it is possible, but really hard to maintain.

AZFX4

Besides doing a basic tune up..

Cai, Exhaust which you have. And you can do a tuner. SCT with custom tunes from Troyer or VMP. Or get a Gryphon(rebadged Edge) and get custom tunes. I have the Gryphon but have not recieved my custom tunes yet. You can also do E-fans and Underdrive pulleys. They will free up some HP and give you a solid 1mpg gain.

I have heard mixed reviews of doing E-fans when towing depending on where you live. But I think with custom tunes it shouldn't be a big deal.

BigRedXlt

Dang I need to learn how to drive like you guys because according to fueleconomy.gov you should get 13 city driving and 17 on the highway in a 2004 5.4 3 valve. If you dont have the 3 valve you should be getting between 11-15. Unless you guys somehow use a sail to propel yourself that seems crazy to be able to gain 4 mpg over the best hwy mpg just by driving "nicely."