04whitescab

My truck got about 10.5-11mpg the last tank of gas I had and about 12.5 the tank before. It was a mix of highway and city driving. This is terrible. I don't expect to have 30mpgs or even 20, but I was hoping to have around 14-15. I keep my RPMS under 2,000 rpms for the most part.

I have the "gotts mod" done to my intake. I also have 2.5 SI/2.25 Dual outlet flowmaster super 44 so I don't believe that air restriction is a problem.

Any Ideas? Do you think this is because of my set up?

*side note, I do have to start my truck, back it out of the drive way, and put it back in the drive way every morning because my truck can't fit in the garage and I have to move so my girlfriend can get out to go to work.
Would this have that big of an affect on it?

5.4L 3v 134,xxx miles, regular unleaded
lifted 2 inches with 285/75/17 Terra Grapplers

I plan to use Seafoam before my next oil change to hopefully help get some carbon and gunk out as well.

dereku

Did you change plugs and coils?

Change trans fluid

Diff fluid

Good battery and alternator good? Could add lots of drag.

Pcv blockage can cause a ton a weird issues one of them being bad mileage. Its often over looked too.

Clean your maf, tb, or iac.

Check for any leaks too especially vacuum.

bubblehead33

just curious,do you live in a cold area? winter is a bitch on fuel mileage. in the fall i was getting 19-20 mpg mixed but with the cold weather, i was down to 12.5-13 last time i checked it. also, check your air pressure, a couple psi will make a difference.

04whitescab

I havent changed the plugs and not sure if they have ever been changed. I would hope so at 134xxx miles. I don't want to attempt this myself and have them break.

I need to do the differential fluid because my 4wd was sticking about a month ago. And I plan to clean the MAF when I seafoam

So this in theory should help at least a little?

dereku

Its not your diff its your transfer case that causes sticking. But do them both. And get those plugs done asap.

04whitescab

I want to replace the plugs but not trying to pay $1000 if they break off inside. I'll just have to see if I can find a place that has the tools to take them out if they do break and wont rip me a new one to do so. This is probably the biggest problem

mhannink

02 sensors? i just bought an 06 5.4, installed an edge evo, and conservative mixed driving got me 13 to just over 14. started doing maintanence and it has started to climb, i changed engine and tans oil and filter, spark plugs, seafoamed intake and fuel system, and finally the 02 sensors. did all of this in stages and each changed how the vehicle drove. the biggest one however was were the 02 sensors. plugs made a difference too but not as much as i would have thought. on a side note, the truck has 160k, the engine was replaced soon after i bought it(oil pressure problem) the "new" engine is supposed to have 40k miles on it. when i changed the plugs i was suprised to see the electrode on the motocraft plugs where nearly gone. i put autolite platinum ht1's (maybe ht15's) in. if the engine really had 40k i would assume these are the original plugs, if so then they need to be changed far sooner than ford says.

04whitescab

Did you clean the O2 sensors or change them?

screw04

Mass air flow, throttle body and fuel filter are the biggest things, make sure tires are properly inflated and do not raise the rpms over 2000 and you can get 15 pretty easy with these trucks. I had mine get 17.5 mountain driving on one tank, got nearly 430 miles to a tank when I was really trying. Now that does take some work and can hold you up but theres no reason to not get 12.5 anyway