hi all. my mom's expedition is not being nice. it is getting about 10 mpg and she drives about 60% freeway. what is wrong here? the truck has the 5.4, its 2wd and the only mods done to it are gibson cat back exhaust and a K&N FIPK. thats it. we needed to put those mods on cause we tow a large travel trailer and they help with pulling power a lot. but why is her unloaded mileage so bad? i dont remember it being that bad a while ago, but she only recently started looking at the mileage.
thanks for any help

 

Yup - that is pretty bad considering I just recently got 21.5 MPG on the highway and 14 MPG in the city with mine (Imperial gallons). I expect it to be a bit better once winter is over as well. If she's only getting 10 MPG, tell her to slow down

 

speed aint her problem. she drives really slow. totally opposite from me in my truck! hehe. she only drives 70 on the freeway too. i dont get it. she has a feather for a foot and she is still getting bad mpg. and we live in southern cali, so no winter gas like some parts of country.

 

Did she have new tires put on? If they're larger diameter tires, that would help explain the low mpg. Was the rear end ratio changed without recalibrating the speedometer?

Is her Expy loaded down for some reason? Some people carry a lot of stuff in the backs of their cars and trucks. That would hurt mpg.

Maybe it needs servicing? Like new air fliter. Maybe she's running the wrong oil?

 

I'm in the same boat. I get 9-10 in the city and 11.5 hwy. That's with 33's on. There's nothing wrong with the truck; I even had the codes checked and Motor-Vac done but nothing has changed. So go figure.

 

We do get winter fuel in So Cal. It's called oxygenated. Mileage goes down.

With engine off. I REPEAT. With engine off. Try to rotate the fan clutch.

I just did my plugs and wires and decided to check my clutch as I suspect that to be some of my mileage problem as well. It spins free and then lags due to the fluid being on one side from being off over night.

After finishing the plugs and wires. It cycle's every 20 seconds. Odd for a cold engine.

If your fan clutch is stuck it will cause mass loss of power and you will hear the fan pulling the air in.
This could be an easy 4mpg.

Mike

 

Maybe someone is consistantly stealing Mom's fuel? Is there a locking gas cap on the fuel tank?

 

thanks everyone. as for the tires, gears are stock. the maintenence is fine. but the fan clutch sounds like something to check. i will do that asap. thanks for the tip.

 

JA,

I'll let you know how the fan clutch works mileage wise, as I just changed it.
For $75.00, I decided to try it. I will say that my other clutch was very suspect, going on and off so rapidly didn't make sense to me.
Just with a 5 mile drive I can say that the truck seems faster on excelleration, and I know that the fan is on at idle and off now when cruising as there is no excessive load on it.

More info this week when I hit the highway.

By the way around town was 12mpg, and on highway was 16 barely.

MK

 

Spins free? By how much? Should there be alittle resistance when hand spinning the fan? Just curious, because mine cycles on and off alot.

 

I bought a Hayden clutch, and the instructions on the box say that if you can spin 1 to 1 1/2 turns before resistance than you have a problem.

I had about half that but figured, what the heck, I'd change it anyway. 81K on the ODO.
I'll post back here later in the week as I got a 430 mile drive.

Mike

 

i had the exact same problem... generally replacing the spark plugs once and a while helps. mine was down to 14, and it will probablly go out up again, now that i have put in new plugs

I find the champion Copper plus plugs are good, but are only good for around 20,000KM (and i also run a 4.2L too).

 

As promissed. Here's the info on my 430 mile trip this afternoon. The fan clutch works good, but the mileage is the same lousey 15-17 on the highway.
I will say this though. The truck runs smoother. This no doubt is from the wires and plugs.

Have a nice week.

MK

 

I can speak from experience that most fan clutches are grasping to try to give you +0.10 mpg.

Been there, done that, electric is probably going to be the most beneficial unless you have electrical problems (with max a/c on in the desert, going up hill.. it will all hit the fan)