i just bought a 2003 f150 super crew 4x4 with the 5.4. i hear bout people getting 13 to 15 mpg. my truck is all stock. when i bought i did a complete tune up on it. i bought autolite iridium plug, replaced all boots, springs, and coils with bwd brand. im only getting 11 on the highway and about 9-10 in town. i was told putting summit headers on it helps it breath which improves the mpg. i was looking around on the internet looking for a programmer. but i dont want to spend the money on one if it would help at all. i was wondering if anybody knows something i can do to improve my mpg?

 

Not for nothing but did you clean your mass air sensor? And maybe replace your fuel filter. Is this a 4x4,? Make sure you use mass air cleaner spray if you do it.

 

Sorry you did say its a 4x4 they do like a little more fuel than 2wd. One other thing is you may want to check into replacing the fuel pressure regulator. It is the year 2014 and your truck is how old. That diaphragm inside is at its age limit. I had one of my customers fuel pressure regular leaking fuel inside the vacum side and fuel mileage took a toll when fuel was being sucked in thru the vacum lines and intake. If it was me I would change the fuel pressure reg to have some peace of mind. And clean the mass air with a fuel filter if it hasnt been done. Let me know how it turns out.

 

You *should* have used Motorcraft platinum plugs and either Motorcraft or Visteon coils.

 

would if make a noticeable diffrence if i put motorcraft in instead of autolites.
i put on a new fuel filter on yesterday. i cleaned out the mass air senor as well. i really havnt travled enough to tell the diffrence. i am going to go back home this weekend which is 300 miles so i hope it help my mpg.

 

A programmer will help with responsiveness and shifting, make it more fun to drive, but normally does little or nothing for mpg.

 

This. All ford for sensors and electrical items.

 

If there is not a missfire the coils and plugs are working. Did you change the o2 sensors? They get old and WILL effect fuel economy long before they die completly. Go to Rock auto and try to get the motorcraft but if you have to substitute use Bosch. Always remember Motor craft parts are best. If you dont use them the part is always going to be suspect. I think most likely your not haveing and issue with the stuff you already changed. Spend your money on oxygen sensors next.

 

You should only need the 2 front O2's, the rears won't affect mileage.

 

BTW I have the same truck (only 99)and I hhave only been able to get it average about 13. It'll get 15-16 on long highway trips and it can get pretty bad 10-11 if I'm driving around town You can do a little better. But not much!