My names Kip and i own a 2003 F-150 Ex Cab short bed lariat FX-4 and about 65K on it. Its got the 5.4 and i love the pickup, except for a few things i need help with.

1- Mileage) I need some help in this category. I put a true flow intake, and a Gibson single exhaust on it, as well as 33 BFG KM2s and i cranked the torsion bars up a little, and it gets terrible mileage. I get an average of 215-230 Miles a tank- About 20-21 Gallon fill. Just a little over 10mpg even when calculating for the tires. What can i do to get better mileage? The tires are not going, and i am very mechanically/motor savy and build performance atv motors so im not an idiot as far as performance. How good are the exhaust and intake that i bought? And what are my next options as far as power/Mileage improving mods? What parts are a joke, and what parts are good?

2- Power) Ive driven a few 5.4L F-150s and they dont seem to have a ton of power. They do ok, but my buddies 98 K1500 kicks my *** with his stock 350. I think its a gearing difference, but what can i do to give this thing some more power. Especially for towing.

3- Everytime i pull a heavy trailer with it, or run the crap out of it, it gets a lot better mileage. Significantly. I replaced the O2 sensors cause they were reading bad, but what else could i do to fix this? It cant just be cleaning out carbon can it? Mass Air Flow Sensor?

Thanks!

-Kip

 

ttt

 

I'm not exactly sure but I can say that the 5.4L is somewhat under powered itself. Then the obvious.. keeping things clean like MAF, injectors..etc I've even gone and pulled my whole intake plenum and throttle body off and completely cleaned all the carbon build in them. I have some before and after pics.. its amazing and was a noticeable difference. And with a 6" lift, 37x13.5 tires, 160k miles... I'm getting around 10 city and 12 highway on just a 3" air raid intake and SI DO 40 series flow masters with everything clean and chevron fuel only.

 

maybe try running seafoam through it

 

Like this

 

prolly the best thing you could do would be to get a tuner and for the i would recoment a grpyhon tuner with custom tunes for tow , performance , and ecomony , that would help out alot and prolly cleaning the maf would help to if its dirty

 

Thanks for the help Guys. Ill try the above.

Cool Pics BTW. Are any gaskets or anything needed when taking all that stuff off?

-Kip

 

hey Toyz how many miles were on your truck when you cleaned it? mines got 145000 and has a "miss" at idle and I've done the coil packs and plugs checked and cleaned everything and my next venture was to take off the throttle body and clean it. It almost feels like a vacuum leak but its not.

 

seeing that clean throttle body has inspired me to clean my own out!

 

It had about what you've got, 145k, was running a little rough and mileage was poor. When I had that no start issue with the IAC I decided to take it a few steps further and went for the TB and intake area. What a surprise when I opened it all up... nasty nasty, some areas had close to 1/8" of carbon build up. Butterfly valves were sticky, passageways were clogged. I also cleaned the egr side, that was probably the worst, took some pipe cleaners and lots of intake/carb cleaner.

As far as the gaskets, I was very gentle with removing the TB and was able to save a surprisingly in very good shape gasket. Was also able to reuse the IAC gasket. Had a bit of damage to the egr gasket when removing the egr so I replaced that. It is very crucial to have good clean surface and a sealed gasket.... and for only a few bucks it doesn't hurt to have the peace of mind that they are new. And it helps you get to the back of your throttle body and really be able to check for cracked hoses in the way back where they were common.

couple of tips....
make sure every socket or tool you use is connected good, worn out sockets that fall the the end of the ratchet are a no no. I spent 2 hours searching for a socket under the intake plenum. Also make sure no bolts/nuts drop down into the actual intake. Not hard to do, just pay attention.

I think this cleaning (other than the search for the socket) only took me about 2 hours total, was pretty simple. And definitely worth it. Better mileage and a lot smoother running.

Here's the write up that I used to reference everything
http://www.fordf150.net/howto/throttlebodyclean.php
I didn't follow it step by step and my 5.4L was a bit different but it was helpful