MPG are horrible!? even for 5.4l!

[jlo82585]

hey y'all, first off im not complaining about fuel economy, I am very aware that I bought a v-8 on a 7 thousand pound truck. I am curious though as to why my mileage seems to be so much worse than other expeditions. I have a 2002 eddie bauer expedition with 147k miles. I just bought it so the only things I have done for it so far is change the oil and air filter and do the gotts mod to it. It needs tires and I will be getting them shortly as well as having my exhaust straight piped after the cats. I am seeing about 9 MPG in town ( about average ) and 12.5 on the highway ( well below average ). my brother usually sees 14 on the freeway and my sister claims her expedition gets between 16-17 on the freeway so does anyone have any ideas as to why mine is so much worse? the original window sticker for my truck says 16 highway and 12 in town. Are the numbers im seeing about normal or is there something I should be checking?

 

[MoHawk]

Was it ridden hard and put away wet? My 2005 gets 15 city and 22 Hwy....

 

[bedrck46]

whens the last time you changed plugs COP's etc, clean the throttle body exhaust ports What your getting highway I get around town and I haven't changed plugs yet I would expect you to do somewhat better

 

[jlo82585]

I don't think so, the engine doesn't burn a drop of oil though it leaks a few drops a day, after changing the oil and going about 500 miles the oil still looks totally clean so the rings would appear to be okay. The exterior is 100% clean ( except the typical rocker panel rust ) and the interior looks brand new. it does have an exhaust leak and the transmission needs to be serviced as the fluid is very dirty but all in all it seems to be running great. no CEL ( when I bought it the CEL was on due to the MAF sensor being unplugged ). your 05 would have the 3 valve 5.4 so you should be getting better mileage either way but for the 2v 5.4 im still way off what I should be getting supposedly. I haven't changed plugs yet, im actually dreading it after seeing where they are located but that is my next step. Should I replace coils with plugs?

 

[tonydiv]

Those mpg numbers are worse than my truck was getting with the setup you see below.

It's time to hit all the basics. Fuel, air filters. Clean mass air meter. Sea Foam the intake. Change fluids. Check air pressure in the tires. Ignition system maintenance.

Once all that is all done. It's time to check the rest of the driveline to make sure that nothing is dragging.

 

[bedrck46]

if you don't change coils at least install new boots and use dielectric grease Clean the throttle by removing it from the intake pay attention to the exhaust ports thru the TB

Also agree with above by tonydiv

 

[jlo82585]

well ill be dropping the fuel tank soon to replace the fuel level sending unit so ill change the fuel filter then too, air filter is already new as is the oil. Just got the tax return so ill get some new rubber as my current tires are worn, weathered and one has a broken belt. when I pull the TB isnt there a gasket ill have to replace? and do I just use carb cleaner to clean it out? plugs are in order as well, as for the dragging, it seems at low speeds 1-2 mph when I crank the wheel on pavement the front tires drag a bit, I was told this is normal. I can hear the T-case engage / disengage when 4lo is selected so as far as I can work out that is all functioning correctly.

 

[allanbegg]

... and the transmission needs to be serviced as the fluid is very dirty ...

Transmission slipping, perhaps?

 

[bedrck46]

you will need gaskets for the throttle body also use throttle body cleaner. Some good videos on youtube about cleaning TB's since your dropping the tank you may want to consider replacing the fuel pump as a complete unite being your mileage is up there unless you know if and when the pump was replaced.

 

[toms89]

It may be worth changing the upstream O2 sensors. (nearest the engine) These are used by the pcm to tune the engine. You can have your exhaust checked for back pressure to determine the condition of your cats.

Do you keep your tires properly inflated?? Rolling resistance can have a big impact on fuel mileage with a heavy suv. I like to keep mine on the higher side to help reduce rolling resistance but well within the range of the tires specs. Tire wear and comfort are possible disadvantages but you can monitor tread wear and alter pressure as necessary.