One small question about fuel mileage

[rocketvette95]

I know that this issue has been beat to death,but I went on my first long trip across NC. When we left I filled up,drove for a couple of hours stopped for a break and thought I would go and fill up since the gas was a little cheaper. after driving for a couple more hours,wife needed a stop (like most). So when we got to our destiantion I sat down and to fiqeure some fuel mileage. Now I know that my 2002 Expedition EB 4x4 with 164000 miles and with 3.55 gears,is not going to be the best in the world but when I found out I am only getting 13.4 to 14.6 I like to have fell out of the chair. I have changed all the fluids and gone with all syntheic which I thought would have helped little. The only thing in the truck was me and my wife a one bag of luggage. I set the cruise on 76 mph. I knew it was going to be bad while in the mountains so that did not bother me,but when we got to the flat lands I thought it would have improved.
I know that this is a heavy tank and I am not trying to get 20 or more but man is there anyway to atleast get 16 to 17.5? I kept the RPM's under 2200 but that did not do anything.
So is there any improvment out there or am I just going to have to live with it

 

[Brusky]

I get a little better than 17 when I drive the almost 3 hr trip to my dads every few months here in Florida. Running about 75mph.
That 13.5 - 14 is what I get average just filled up today and math came out to 13.79mpg. Mostly city 123,000 on the clock

 

[96mustangV6]

On my 98 Navi with 8 people a luggage on roof goin from middle of missouri to chicago Il. So half hills and half flat. I avg about 14.5mpg. I figured not to bad for a 6000lb plus everything/everybody in it. Even with my 22s i avg bout 13.5-14 on highway.

 

[alaskanexpy]

yeah thats not so good when i can get 14.5 with my V10 excursion 4x4 in the alaskan mountains. i've seen nearly 18 mpg with the expy before, my prob it i hardly take it on long road trips i always use the bigger truck.

you should be doing much better then that.

 

[rocketvette95]

Well that is what I was thinking. I knowthat these trucks weight over 5000 lbs,and like I stated before I am not wanting to get over 20 ( God would that be really nice). But I would sure just like to see at least 16 to 17. I know that living here in the NC mountians I am not going to get any type of gas mileage because of the terrian but as soon as I get over Black Mountain the mileage sould improve to 16 or maybe 17
Now I will have to say that I did lower the air pressure down to 35 and the tires are a set of Cooper ATR P265/70/17 so these are NOT 10 ply's.I did change the Transfer Case fluid to Mobil 1 ATF,Changed the Rear axle to Valvoline Synthetic 75/140 along with 2 bottles of friction modifier. Changed the Trans fluid to Mobile 1 ATF. The engine is using Mobil 1 5w30.
I DO NOT drive the piss out of it 90% of the time. Most of the time I drive it like most Middle aged males not driving a Corvette or Porshse.

 

[alaskanexpy]

I DO NOT drive the piss out of it 90% of the time. Most of the time I drive it like most Middle aged males not driving a Corvette or Porshse.

ahh maybe thats the key! i drive mine like a stole them all the time haha!

 

[BANGEREXPO76]

From my experience. Doing 76 MPH in these heavy trucks is going to get you 13-14 MPG or less. Your not seeing 17-18 mpg in these trucks unless your doing 55 with everything tuned up to spec.

 

[Bowesmobile]

I get around 17.5 - 18 and I'm doing 75-76 in mine almost every day. Its a first gen with 3.55 gears. We dont have mountains. But we are not flat here in Richmond either.

 

[71Rcode]

Our '01 4x4 (3.31s) is only driven on the weekends to kid sports events and the like. I rarely get her over 55mph. I'm averaging 11 mpg driving her like a BABY.

Just like driving a musclecar back in high school in the mid '80s... without the power.

I'd be shocked/pleased if this tank got 17 mph on the flat TX highways running at 60mph. But you guys give me hope that she may.

 

[BANGEREXPO76]

I get around 17.5 - 18 and I'm doing 75-76 in mine almost every day. Its a first gen with 3.55 gears. We dont have mountains. But we are not flat here in Richmond either.

I'm on the highway everyday I have new everything under the hood and under the truck. Doing 75 MPH only gets me to E faster. The only way I can make my truck get a 17 MPG reading on the actual gauge is to drive 55 on cruise. The 5.4 based trucks are only rated to get 13 city & 17 highway off the lot.

 

[toms89]

I'm on the highway everyday I have new everything under the hood and under the truck. Doing 75 MPH only gets me to E faster. The only way I can make my truck get a 17 MPG reading on the actual gauge is to drive 55 on cruise. The 5.4 based trucks are only rated to get 13 city & 17 highway off the lot.

3.55's or 3.73's?

Rear gear ratio, motor (pi vs non-pi, 3v) make a difference. Its a given that 55 has less aerodynamic drag than 75 but where you are at in your engines powerband also has an effect on load.

 

[Bowesmobile]

I'm on the highway everyday I have new everything under the hood and under the truck. Doing 75 MPH only gets me to E faster. The only way I can make my truck get a 17 MPG reading on the actual gauge is to drive 55 on cruise. The 5.4 based trucks are only rated to get 13 city & 17 highway off the lot.

Well there is one difference. I have the 4.6L. Not as much power but my gas goes further. I try to keep the RPM's around 2200-2300 when on the highway. Works pretty good for me. I'm shooting for 20mpg. Hopefully with an exhaust and electric fan I'll be that much closer.

 

[toms89]

Well there is one difference. I have the 4.6L. Not as much power but my gas goes further. I try to keep the RPM's around 2200-2300 when on the highway. Works pretty good for me. I'm shooting for 20mpg. Hopefully with an exhaust and electric fan I'll be that much closer.

But my gas goes faster!! .......................

 

[rocketvette95]

Thanks Guys. But what is really killing me is that my last 2 4x4's (2000 Land Rover Disco II and a 1996 Lexus LX450) got better fuel mileage. So I know that the Expedition is a 3 ton truck,but I was really hopeing that there was some higher gas mileage somewhere. I am not knocking the Expedition at all,it rides and drives almost better than a Cadillac. I was just trying to see if I may have been overlooking something. I will say that I filled up in Raleigh and drove 271 miles and only had 1/4 tank of gas left.

 

[Bowesmobile]

But my gas goes faster!! .......................

I'm working on mine going faster too! Just with less displacement. I will say there are a few reasons I want a 5.4L instead of the 4.6L.

To the OP,

I work 50 miles from my house. So I drive 500 miles a week. I get 425 miles on a tank average. So far I have done the Gotts mod and a K&N air filter. I'm changing over to a coil suspension and getting rid of the air ride. Since my system failed Sunday. So I dont know if that will increase or decrease my mileage at all. I also have the third row seating that adds weight.

 

[toms89]

Thanks Guys. But what is really killing me is that my last 2 4x4's (2000 Land Rover Disco II and a 1996 Lexus LX450) got better fuel mileage. So I know that the Expedition is a 3 ton truck,but I was really hopeing that there was some higher gas mileage somewhere. I am not knocking the Expedition at all,it rides and drives almost better than a Cadillac. I was just trying to see if I may have been overlooking something. I will say that I filled up in Raleigh and drove 271 miles and only had 1/4 tank of gas left.

I think you should be doing better with hwy miles. 16mpg is a reasonable number unless your lifted, running larger tires, modified, etc... The sweet spot in mine was around 70 mph. Took very little throttle input to maintain speed. Below that it would require more throttle to maintain speed up hills.

IMO.. I would focus more on your right foot than rpms. Lower rpms do not help if your having to modulate your right foot more to maintain speed. Low rpms and overdrive may load engine more on slight inclines.

Its also possible its ready for a tune up.. air/fuel filters and plugs. If your fuel milage continues to decline I would recommend new front O2's. These are used by the pcm to control fuel trims.

 

[rocketvette95]

Well my EB has the factory coil spring/torsion bar set up with no Air Ride. I have taken the third row seat out just to see of that would of had any effect on the mileage,but it seemed to of gotten worse. I did replace the fuel filter abou a week ago,but that is about it. I have really be thinking of going to look at a 2005 Expedition EB 4x4 but I would really like to keep what I have.

 

[superexpy]

Im starting to question if I got 373. I got to be going around 80MPH to see over 2000RPM with OD on. My door tells me I got the 373 rear. If I remember corectly I took a three hour trip to the dunes with three quads going around 70 - 75 the whole way and it only took me a half tank. I think my overhead MPG said something like 13 MPG and I remember thinking it has to be off. I do have alot of go fast crap on my Expy so I am not suprized if my milage is worse than others.

 

[rocketvette95]

Well I am just about 99% positive that mine are 3.55 with a rear locker. I can remember back in the mid 80's,I was messing with my 85 Mustang GT and if you had a 5 speed you wanted to go with the 3.55 and if you had a automatic you went with 3.73. But when we would change the gears most of the time fuel mileage went up as long a you kept you foot out of it.

 

[GAINMOB]

invest into a programmer...exhaust...intake or gotts mod...efans...i get 18....CITY