Poor gas mileage
 

I was wondering what other tune ups I need to do to my truck to get the gas mileage to go up. Currently I only get about 14 mpg regardless of how it is driven. The truck has 115000 miles on it. I have done plugs, fuel filter, air filter, cleaned the mass air sensor. It doesn't seem to misfire at all, and there are no check engine lights. Also I have had a coupel of O2 sensors replaced. What other things need to be worked on? Would replacing the COP's increase the mileage at all?
Thanks
Tim

Welcome to my world. My 95 F-150 4.9l w/ M5OD R2 has gotten 14 mpg since the day I bought her no matter if it's in town or on the highway. Guess if I was really concerned with gas milage i'd drive a rice burner. lol But anyhoo, if you've done a full tune-up theres not much more you can do unless you start adding stuff ie: K&N Filter, synthetic oil and whatever else you can dig up. Good Luck

Gas Mileage
 

Hello,
I have a 2000 F-150 2WD 5.4 with 3.55 gears. I was getting some pretty good mileage 15 city, 17.5 city/hwy, 18.5 hwy, with 235/70/16 tires. My wife and I decided to buy a travel trailer (4800) loaded. Shortly before buying the trailer I decided to go with larger tires 255/70/16 what a mistake. City mileage drop to 13, city/hwy 15.2 but hwy went to a incredible 20.3. This was tested several times. Then I hooked up the Trailer, I now have to take out a loan just to go camping somewhere, the first time out i got 11.2, the last time I took it out I got a 10.1 miles to the gallon. I have used K&N filter no change, injector cleaner no change. Do you have any Ideas? I change the oil every 3000 miles and the fuel filter is being changed this week I have about 27000 on the fuel filter, I'm going to go back to my fram filter to see if that helps.
I just cleaned my K&N air filter is there a chance I sprayed to much oil on it? The engine runs smooth, and has great power.
One other thing when driving on the hwy with the trailer it sounds like the clutch fan ingages for some reason. Boy is it load the only time I here it like that is in the winter when I first start up the truck.

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Im getting 16 mpg with my '99 F-150 (4x4 reg cab, off-road package) with a 5.4L and 3.73 gearsunder normal driving (60% country backroads, 40% city).
Id try a K&N (it gained me 1 mpg) and check your tire pressure.
Other than that, perhaps try accelerating smoothly and lightening up on your right foot a little bit.
Octane

I wish I could get 14 out of mine. The best I have seen, even with my upgrades, was 12.7 MPG. These trucks just don't get good mileage.

Thats load of BS. My parents are getting 18 mpg highway with their '04 F-150 SuperCrew (5.4L, 4x4, 3.55 gears) and like I said, Im getting 16 with mine back and forth to work.
Heck, my brother is getting 16 mpg highway with his '99 F-250 Super Duty (supercab, 8' bed, 4x4, V10 with 4.30 gears) but he is also running Amsoil synthetic.
Id still take a Ford over a GM or Dodge when it comes to fuel milage!
Maybe if you got ride of those 35" tires and put back on the ones that it came with you could get decent milage. Bigger tires will gain you better fuel economy when driving at steady speeds, but when you climb a hill or accelerate they absolutely RUIN your fuel economy!
Octane

I get about 18 to 19 on mine andit's city/hyway driving. I did nothing different but give it a good tune up and add synthitic oil (castrol). Changed the tranny fluid as well and filter.

I have read all the messages in the thread and I don't know if this will make a difference but the tranny fluid should be changed periodiclly, I say 30,000 with filter. if changed it could get better gas milage, just a shot in the dark. possible though.

If you do try changing the tranny fliud and fiulter make sure you put the right fluid in! it does matter and the two transmissions take different stuff Dex/Mercon III ver Mercon V.
Lance

I've avg 17.5 mpg on my 98 F150 4.6L 4X4 Off Road since brand new. Mainly highway miles also.

i get horrible gas mileage with my 1998 Expedition and I also have a problem with it eating oil by the quarts? by the time i need to change the oil again there's only about 4 quarts left in there?

anyways, i've always heard these things suck where gas mileage is concerned especially if there are any other emission issues going on. if you noticed a sharp decrease in gas mileage then keep your eyes open for your check engine light as there's probably something going on that just hasn't triggered the CEL yet.

good luck.

My F-150 has a small oil leak between the head and block. It doesnt use coolant, and the oil doesnt look milky when I change it. I think that one of my headgasket o-rings is cracked and is allowing oil to leak out. Its not a bad oil leak, it leaks less than 1 quart over the course of 3,000 miles. To be on the safe side, I add 1/2 a quart after 2,000 miles.
It cant be hurting my engine too bad though, it still pulls 16 mpg back and forth to work (mix of city and country backroad driving) and on the highway it gets 17-18 mpg. Considering that it has a 5.4L with 3.73 gears (it turns about 1900 rpm at 70 mph), Im fairly pleased. Not too bad for a truck with 124,000 miles on it if you ask me.
Octane

I didn't put these tires on the truck. The previous owner did. I know my mileage AND power are suffering from these oversized rubber pillows. But at $190 a pop for the 285/70 17's I want...I'll just let these tires wear down to racing slicks before I drop the change.