My truck gets 16 mpg on the interstate if you drive it like a baby, and it is blown. Around town I get about 10 or so, if I stay out of it. Now when I start playing with it, I get around 6 mpg or so if I am lucky. More boost = a lot more gas. When the motor was stock with a programmer, Jacobs ignition, K&N CAI, JBA headers, and Borla exhaust, I could get up to 22 mpg with a 4.6 5 speed truck.

 

Your mileage is way off. I'd suggest going by any Auto Zone have them check for any codes- it's a free service. Once you've eliminated the mechanicals, you might need to learn how to drive for fuel mileage. I have an 04 SCrew with the 4.6 and I get 18-20 town and 22-24.5 hiway. If yours has a tach in the dash, I push the footfeed down enough that the transmission goes thru the gears but the tach never goes over 1800 RPMs until I'm in OD and then I drive 65 or less. I keep the tires aired up to the max as stated on the tire sidewall. For my tires that's 44 PSI. No, you won't be the first away from a stop light but the morons that want to fly aren't paying the gas bill so get accustomed to seeing folks IQ number. But your mileage is not right and it's either driving habits or mechanical.

 

I have a 2004 Heritage with the four six and get around 22-24 on the hiway as well even with a motorcycle in the box. Around town it gets less but then again so does everything.

Perhaps it could be a dirty throttle body or MAF sensor. Even different fuels give different mileage....

I have a CAI, duel exhaust and a tune (all from my other F-150 when I traded it...).

 

wow....you are correct dude..so does havin your tires at 44 psi good...cuz i was thinkin 35 are good...maybe i should try 44...and ive gotta drive 20 miles to work and another 20 back home..about 16 is highway..maybe i should drive 65 instead of 70.and not try to get to 70 as quick as i can.i keep it under 2300 rpms..maybe i should try 1800-2000 rpms..and yes...when you come to a stop light people are goin to come flyin past you

 

Just read the side of the tire, it tells the optimum presure in the fine print
In stop and go traffic and cruising at 40 mph or less always turn the OD off.
Do check the codes. There san be preliminary codes that haven't triggered the light.

 

There HAS to be something wrong here. In another thread in a different forum, I talked about getting 12.9 mpg pulling a 3600# trailer over the high passes in Colorado. I get something in the 15s when not towing in ordinary driving.

Is your odometer correct? If it shows fewer miles than you've actually driven, this could account for a poor gas mileage.

I'm also hard-pressed to think your driving habits could be responsible for mileage that's this bad.

In fact, it's hard to believe your truck's tune could be so out of whack to give you these figures.

So, no real suggestions, but something's really wrong here!

- Jack

 

and another thing you might not be checkin your milage right....if you fill the tank up to where not another drop of gas will fit..then the next time you fill it up just to where the pump stops..your milage will be wrong...what i do is when the pump stops round it off to the next dollar (so i dont get change ugh change) then reset my trip..then crank it up and start drivin...and dont let it sit and idle as much as you can....let it idle as little as possible...cuz your gas milage goes down when you idle...and when i run it down to dang near empty...i fill up to where the pump stops...then round it off to the next dollar (so i dont get change ugh change) then trip divided by the gallons you put in..then bam theres your milage..then i reset my trip start it up and drive.. and i DO NOT let my truck idle very much

 

yea i know where it is..and i know my tires say MAX 44psi meaning the MOST you should put in there is 44 and really turn od OFF when goin under 40..might try that..i never in my wildest would think thats it

 

yea i dont think theres anything wrong with the truck...he must be driving like a idiot..cuz i could drive my truck like a idiot (pedal to the metal and driving the whole way to work at 95 mph) and i dont think i could get that low in my truck

 

Ah - Tumba, I think you've got something not quite right here. The pressure stamped on the side of the tire is a "max" cold inflation pressure. There are stickers all over my truck (driver's door and in the fuel door, to name two) that say to inflate the tires to 40 psi (which is less than the max pressure) but is what is needed to allow the truck to haul the GVW it is rated for. The max pressure is a "do not exceed" pressure that might keep you from having a tire blowout at crusing speed.

And, why would you turn the OD off in any kind of "cruise" situation? OD lets the engine run at lower RPMs, using less fuel. It doesn't provide as much "pulling power" but you don't need that while cruising, and it doesn't "kick in" until you've reached a low "power need" throttle/speed point anyway. About the only thing turning OD off does, is reduce "shifting" in stop and go situations, which may be easier on your transmission.

If I'm wrong on any of this, there will be a ton of responses that will correct me!

- Jack

 

I don't think that the under 40mph OD is your gas milage problem, it's just a good practice. IT is strictly for the life of the transmission.

 

thanks for backin me up on the tires there jack..and i didnt think turnin OD off would help im gonna ease up on the gas pedal a little and slow down a tad...65 instead of 70 air my tires up to 40...throw cats back on...lol...and a cold air intake...

 

I wasn't trying to argue!

 

were all friends here Tumba! we dont argue here...except the very few a holes that start stuff! besides that we dont look to start arguements!

 

JackandJanet, the tire pressure labels on your truck is for the best ride and still meet the requirements of the carrying capacity. But, here's one for you to consider. My Bronco came with 235/75/15 tires and I have labels all over it stating that the tire pressure is to be 28lbs. I didn't keep those tires on it a week and put 11.50/31/15 Michelin LTXs on it. The max tires pressure for the LTXs is 50 lbs. At 28 lbs the tires will certainly come off the rim in a hard turn as they are half flat. Running tires at the auto makers recommendation would be a case for disaster. The COLD max pressure allows for the air expansion at hot temps. I've run tires 10 lbs over COLD max and have never had an issue in our extreme heat of S Texas where we generally have over 45 days of temps over 115F and 96 days of over 110F. Just like most manufactured things, there are safety measures built in and running COLD max pressures is well within the limits of quality tires.