Ive got a 98 exp with a 5.4 and 3.73 lmt slip. I just bought it for the original owner. I was told that they got around 14 mpg but I thought people were crazy. Well sure enough... Is there a reprogramer out there that will increase the mileage? I'd hate to have to sell this rig, I love it!
Why I figured it would get better mileage, if you figure out that 5.4 liters at 1850 rpm's = 60mph. That doesnt seem like it would be ingesting that much fuel, unless its running ultra rich to keep it moving. 5.4 ltrs is 1.4 gallons of air fuel mix per 4 rotations of the engine. @ 12:1 ratio air fuel mix it doesnt seem like that much gas is being injected into the engine.
Who has any ideas.

 

I have the same truck. My wife gets 10 MPG out of it city driving and I can squeeze 16 MPG out of it on the highway. I ordered an Xcal II from Troyer for the purpose of getting better milage, but they don't gaurantee better milage, so they talked me into a performance and tow tune instead. I've heard some people claim to get better milage on the performance tune, so that's what I'm hoping. I'll post results when I get mine, but from the looks of it, it won't be until Christmas :santa: .

 

Depending on your driving habits, you can expect somewhere between 14-16 MPG. Considering the size & weight of the vehicle, that's not that bad. If you upgrade the intake, exhaust and tune it you will get a few extra ponies, but MPG typically gets no better and often gets worse.

In comparison, my I6 Grand Cherokee and V6 Liberty got no better gas mileage than the Expedition. So, I really can't complain.

 

Agreed,
My '99 EB 2X4 gets 15.5....mostly highway. My '97 Jeep GCLtd 4X4 got almost exactly (15.4) the same. Both V8's.

 

It all depends on driving habits, if you are hard on the gas it's a pig on fuel. I usually average 15-17 on the highway and about 13 around town. I have gotten as good as 21 but that was with a good tail wind about around 70 mph and as bad as 13 mpg at 70 mph pushing wind.

Around town I'm very light on the gas and use the cruise all the time on the highway.

 

I get 14+ mpg with a chip, superchip tuner, magnaflow, k&n cold air, wires, plugs... but i got 35s (BFG) and lift.... do a tune up i assume you have alot of miles on it, and it will help, flush everything and replace all worn items...eventhough its not broke, it still affects overall performance.... be warned, its expensive owning and EXPY.... if you want good mpg, get a honda, if you can afford and EXPY, you can afford the gas.. thats my 2cents

 

Any small car would be your answer lol what about a young priest and an old priest lol. The bigger the vehicle = bad mileage also more displacement.

I had a 1990 454SS 7,8,9 maybe even 10 MPGs had to fill up every 3 days.
At the SRT10 forum one of the guys there his motto is 1mpg per Cyl.

 

If I said my Exped is too slow who would reply, "these are big vehicles, if you want more power get a honda"? Whats that all about?!
I now set the cruise at 57, I got 15.5 once and then 14.5 mpg. The engine is turning at 1750 rpm's. How rich do these things run? 1750 rpm's should be the same if the motor was in a crown vic. If the engine has a hard time keeping up the speed you'd think the motor would be turning a lot faster, not running a lot richer.
Things I've found out that I might look into incase you're interested:
1. O2 sensors.- cost ya bout 200+ to find out if thats the problem so Ill do these close to last.
2. MAF- should be cleaned every 6 months with only electrical connector cleaner. If you have a K&N filter, you need to clean the MAF soon after you oil it becuase the oil soils the maf wires.
3. Tune up, specifically good plugs, and synth oil.
4. ECM tuner- no one seems to make one of these dirrected towards mileage.
5. Beer and aspirin. finding out how to get better mileage with these vehicles takes some research. haha.
6. Talked to a toyota guy that told me his 6 banger lost the fuel pressure regulator and it spiked the fuel pressure. Didnt set off any codes and gave him 10mpg. He said that it smelled really rich though. So Ill check the fuel pressure in the lines.

I'm gona make this my project. If any engineers out there might be able to help, let me know about the fuel map. By the way, my truck revs to 2000-2200 on start up, that seems high, is that an indication of anything?
By the way, how much tension should be on the fan belt? Im getting noise from that area and dont know if it's coming from the tensioner or the idler pulley.

 

14mpg - you are not too far off. should get better on the highway unless you really accelerate hard and ride over 70. i get 17.5 at 70, 16 at 75 and sharp decreases at 85 and faster.

i did not notice a difference in city driving when i used slow acceleration. 14 is it. that was printed on the sticker when i bought the thing - 14 city, 17 highway.

 

What's that all about... are you kidding? I don't know what kind of responces you are expecting, but there is no way your going to turn your Expy into an econobox...

Anyway, I think your driving down the wrong road.

Even IF you are able to get a custom tuned chip, programed for max mpg, I think the absolute best you can even dream about is perhaps a 5% increase in fuel economy, and that's what, an extra 3/4 of a mile per gallon....

And at what Cost? Hand held programmers sell for $200+ with custom tune chips running about twice that... you would have to save a whole lot of gas to break even.

I think you need to start with the plain ole basic simple stuff. You have a 5500# plus vehicle with the biggest availible engine that isn't very aerodynamic AND it's geared for towing, not economy...

1. make sure you have a clean air filter
2. clean your mass air sensor
3. how old and in what shape are your plugs
4. what shape is your EGR in... clean it too
5. make sure you have your tires fully inflated
6. Have your alignment checked
7. check and see if your parking brake (or service brakes) are dragging
8. remove any exterior items that contribute to aero drag... lose the roof rack
9. LOSE WEIGHT! If you don't use it, remove your third row seat and anything else that you don't need to truck around.


And most important
10. adjust your driving style... get out of the fast lane, lift your foot off the gas in anticipation of any slowdowns or stops, axcell slowly and don't let her sit and idle.

if that don't help, trade her in for an Escape hybrid

 

I have an 03, 4.6l. I did the TP Xcal2 tune (93 performance), AF1 intake and Royal Purple oil. Cleaned the inside of the engine with Sea Foam (made it very nice and quiet), cleand the MAF. Stock plugs (only 40k miles; bought with 27K), stock everything else.

I get a flat rate 15.5 combo city/highway. I never get to try all highway as here in NJ you tend to run out of it after a few hundred miles (or the traffic turns highway driving into city driving).

I datalogged my engine, but didn't have the A/F ratios so TP couldn't tell me too much, however one of my O2's was acting kind of weird. Ether an exhaust leak upstream, or sensor going bad.

Also due for Oil change, clean the MAF.

With a custom tune you may or may not get better gas mileage. You will get very noticiable (and enjoyable) performance in driving.

When I first bought my Exp, it was like driving a pregnant cow. it couldn't get out of its own way. After the tune and the intake, it is very responsive and moves very fast for changing lanes etc. Cruises at 70 mph @ 1800 rpm.

I also hope to find the magic bullet for a few more mpgs, just as a matter of principle. I am trying a gas additive called RxP gas kicker, recently mentioned on one of these forums.

anyhow, if you have the $$, get a custom tune and run the best, highest octane you can. Your driving pleasure will be increased immensely.

Regards,

John

 

Heres way to pick up 1.5 to 2 MPG'S on highway....

1) Draft Busses or Tractor Trailers on highways.. Staying 5 Car lengths behind and you will feel like a NASCAR driver... The bigger vehicles help you cut through the wind like a Civic!

2) How to measure... do the Speed and hit the reset on the MPG meter if you have one... it will give you an instant reading, then get behind bus or truck and hit it again...

I Firgure my NASCAR tailgating plan could bankrupt the oil companies... but tripple the collision and towing biz LOL...

Seriously... try it... really enlightening how much of the bad MPG issue is aerodynamics!https://www.f150online.com/forums/im...ies/banana.gif

 

I want to reply, but the whole "running rich" thing and comparing "RPM" of one vehicle to another has me giggling.

With my 2000 5.4 exhaust, intake, chip I could get much higher MPG in absolutely perfect conditions which would include weather that allowed me not to run the A/C. Towing 7500# would get 11-12 MPG. I thought I got much better MPG than the average Expy., but only when my driving habits directed it.

You're not going to get much more than you have and don't' expect a tuner to do it with a gasser.

Good luck with all the scientific lb/hr, fuel burn and all the other stuff.

 

I dont know why you dont consider 5.4 liters alot of fuel. Not very many vehicles are more than that. The Ford V10 is like 6.8 Liters and the Chevys upper performace engines are 6 something liters. For the size and amount of fuel used these vehicles do very well. That is the nature of these beasts.

 

I guess I am lucky or my AMPG is off. My display shows 16.8 mpg and my wife drives 50/50 street and highway. When I drive highway and reset it while on the highway, it stays 20+mpg no problem.