Hey iam hoping someone can help me. My truck is getting 8.6 mpg ! Im not driving a hummer ive taken the truck to the dealer.they have no idea ive changed plugs bought a coil. Changed mass air. New fuel and air filter. Tires are at propper air pressure. No codes in the system. Its a 2007 mark lt so just nice looking f150 no one can figure it out iam thinking faulty pcm but fords computer says everything is fine. I have no leaks in the fuel system anyones input would be thankfull

 

Hey iam hoping someone can help me. My truck is getting 8.6 mpg ! Im not driving a hummer ive taken the truck to the dealer.they have no idea ive changed plugs bought a coil. Changed mass air. New fuel and air filter. Tires are at propper air pressure. No codes in the system. Its a 2007 mark lt so just nice looking f150 no one can figure it out iam thinking faulty pcm but fords computer says everything is fine. I have no leaks in the fuel system anyones input would be thankfull its a 5.4

 

Winter blend fuel, a heavy foot, and stop-n-go traffic would easily push you into the sub-10mpg range. I drive like there's an egg under the throttle but still only get around 12 in town.

Brad

 

Parking brake dragging will do a number on the MPG's. Also after you drive it a bit look underneath to see if the cats are glowing.

That would be my $0.02

 

I recently fixed my 12mpg highway problem. It was bad actuators on the front 4x4 hubs. Do this to check them:
Start your truck, in 2wd with truck running reach under each side and try to spin your half shafts by hand. If they wont turn then your hub actuators are bad causing the hubs to be locked all the time. After I replaced mine my highway mpg went from 13 up to 16. they are 122 each at Ford and both of mine were bad.

 

Even a small exhaust leak will cause o2's to read more oxygen. I had a pretty small leak that could barely be heard, but it was causing my bad mileage.

 

This. I had a bad cat that was sucking in oxygen and making the O2s go out of whack.

 

Thank you for the suggestions guys ill try looking at my hubs. Does the truck need to be on a hoist for that or just on the ground. I think my eshaust is ok but ill take a further look. I put it on my mac scan tool and o2 s were reading fine but the left rear was responding slower then the rest.should I replace it. You guys have been alot of help, thank you if I figure it out ill be sure to let you know

 

You can't really expect to get that good of mileage from a v8 lol.

 

Ya I don't expect good mpg but it says this truck should get 12 city and at8.6 iam no where close to where i should be

 

My truck feels like it has no power and stutters going up even the small hills

 

There are a couple of things you can do if you suspect the cats, try this link and see if it sheds some light on things.http://www.aa1car.com/library/converter.htm

I think that's the right one.

 

Ill look into the cats is got the dealer to scan the truck thinking cats would of come up but mabey not thanx for the link

 

Yer welcome.