hmustang, I would be glad to show you the mileage results from my rig if you question the 20+mpg figures. Been there and done that many, many times. Note however, I drive a 2wd with a 3:08 rear end. When I'm doing 75 on the freeway, I'm pulling right under 2000 rpms - the engine isn't breaking a sweat!
After 133,000 miles I have a pretty good feel for what this rig can and can't do. 20+mpg happens routinely, for me at least!

If I am remembering right, all trucks after '97 have romeo engines? Maybe I've got that backwards, but obviously if you only want to compare WIndosr Engines and the 4.6 has not been made there since '97, then there would be more 5.4 engines than 4.6.s In then end, there are still probably more 4.6 powerplants on the road today than there are 5.4's due to the use in the CrownVic series, even with the slight changes from cars to tucks.

 

I just filled up my first tank on my 01' 5.4 auto. 13.8 mpg, and the dealer put just a few miles on it I'm not counting.

My 97 -- 4.2 V 6 -- 5spd got anywhere from 13.6 - 14.7 mpg each tank.

That's stop and go suburb and short freeway commute.
I had to get into the 4.2 a good bit to keep the competitive edge over the other maniacs. (read into it all you want...) But, I pretty much feather the 5.4 around. Still trying to lighten my foot to keep from loosening the back end.

It all seems to be a "weight vs. gallons @ acceleration rate".
My truck payment went up, ALOT. But, monthly fuel cost should be the same.

Also, Driving the 4.2 in a headwind 70 miles up or down the Columbia River Gorge required me to drop it into 4th to keep 65 - 70 mph.

****** If a 4.6 was available in a 2wd and I DIDN"T plan to carry much weight, I may have choosen one due to Fuel System reliability, 4.6 vs. 5.4 Engine repair history, and Ease of Serviceability. Invoice Price Wasn't much different but resale may be... ******

My .03 cents worth.
Tim

 

hmaustang..

How come you dont get better fuel mileage???

I get 19.5mpg mixed city/highway...

I would expect-21+ on a long trip...

Have you had yours on a long, highway trip???

How many miles you have???

Do you need a set of plugs..How well is your maintained???

 

Goin from the 4.6l to the 5.4l, our monthly payment was $20 higher.

 

THE 4.6 AND THE 5.4 are the same engine family and design, many of the parts are interchangable. the main issue with the early 5.4 piston slap was because a supplier had problems with the pistons. they are called modular engines for a reason. the 4.6 is used in several vehicles so it only makes sense that there are more of them out there, so does quantity make it a better engine?
every engine ever made has had its problems,

if you are basing your purchase on the fact that the early 5.4 had piston slap (i had a 97 5.4, no slap) then you really are just trying to talk yourself out of the 5.4 . Or the 4.6 is what you could afford and you are just trying to make yourself fell better.

everybody thinks the engine they bought is the best!

 

My old 2000 4x4 OffRoad with the 4.6 NEVER got any higher than the low 19's on the highway, and that was with the Superchip. Bare I got upper 18's...

 

Well, I see 4x4 and offroad in the last post, so there shoudln't be a huge surprise you don't see 20+mpg.

We have a 99 F150 in the family that is nearly identical to my truck - only differences are: 4x4, 3.55 gears vs. my 3.08's, it has keyless entry where mine doesn't, rear discs to my drums, and its a different color (they stopped making moonlight blue -
)

It never sees 20 mpg with the extra weight and gears of the 4x4 system. High 19's, but never 20.

The discussion about the numer of engines on the road came out of the rates of problems on the engines. Just because there are more on the road doesn't mean they are better, but if there are the same or fewer problems with more on the road, it could be said it is a more reliable engine on that basis. In the case of the 4.6 vs the 5.4, I have no idea how these numbers would break out and compare. I can only speak from personal experience...

Peace all...

 

I guess my heavy right foot has something to with my gas mileage in my local driving. I had a good long road trip in August where I drove 4500 miles in one week out west I went up to Yellowstone and down to Zion National parks and drove the limit using cruise going 65 on the 2 lane highways and 75 on the Interstates and got 19.5 on average as of now my truck has just over 38900 miles and I have the oil changed every 3000 or so miles I don't think the 3.55 rear end gear should make that much of a difference over the 3.08 gear but maybe it does.

 

4.6l is good, and when it gets loud, you know you're movin...

The 5.4l gets extremely loud at highway speeds when you're passing, and it literally throws you into your seat...

 

I currently have a 97 F-150 with a 4.6, and it is a "dog" when pulling my 20 Javelin boat. Last week I figured the mileage pulling the boat, averaging 60mph, and it was a dismal 10.5mpg. Going up and down the hills of mid-Georgia keeps you applying full throttle most of the time, to get up the other side of most hills.
I also own a 2001 Expy. with a 5.4, and the differences in power and torque are enormous. Go for the 5.4.

 

I'm with Yankee7985!!! Go with the 5.4!

Gopher, you're probably right... 4x4 + ORP != Good Mileage!
This time I opted not to go with the ORP and just have 4x4... That could certainly explain the fact that I consistantly get .5 - 1.0mpg higher with my 5.4 over the 4.6!

 

I get right at 20mpg with the 4.6, but yes it is a dog...Its the wife truck...she says it dont need to go fast...

If I want to tow I get out the diesel...It will tow 10,000 lbs and still accelerate up the steepest of hills...

It will tow more then I need, I had 16500lbs on it max...

When empty it gets 22.67 mpg best...

not bad for 6500lbs....

If you want to tow or have a weightee vehicle...diesel shines...

I am glad Ford has reconized this and will have half its SUV/Trucks diesel powered in the next 3 years...

The 4.6 modular family was the first high tech engine in America and is one of the best engines designed ever...

So 4.6 or 5.4,,they are both excellent engines and out shine the competition...

 

hmmm, I have a 99 XL, 4.6 w/3.08's, get about 22 hwy, 16 city with 134k on the clock and a "slow responding" o2 sensor

 

Am driving a 98 F-250 light duty single cab 2WD (F-150 body style). Before purchasing we were leaning toward a pickup with the 4.6 for better mileage but am sure glad we got the 5.4 for our kind of driving. On level ground with a light load we are getting 19 to 19.5 mpg if we keep it down to about 65. That's with 3.73 gears and the A/C on. With a pop-up camper in the back and towing a 17 foot loaded water ski boat it can get kind of doggy in the mountain passes, but that's with a full load. Overall we have no complaints. The newer 5.4 3-valve engine would be even nicer.

 

I would get the 5.4 over the 4.6. I had a 99 5.4 and have a 05 4.6 now. I like the 05 4.6 but it definately is lacking some powah.
Thats why we mod these beasts, you can never have enough powah.

Later
M V