It's me again complaining about miles per gallon. Well it seems as though my mpg on highway trips is not much better than city driving. I am highly skeptical about some of your claims when you post your mpg results,truth is refreshing in todays world. Im not trying to vent but how is it that we are all driving similar vehicles and some guys can only get14mpg and drive reasonalbly but some of you guys can drive at 70mph,tow a camper,leave the air on,argue with your mother in law,and perform minor surgery and not even try and still can get 20-22mpg. gimme a break.At a recent visit to my local dealership the service manager told me that mpg results are achieved at 50miles per hour or 80kilometers{for fellow canadians that might read}.How is it then that 70mph gets you better mileage. Please enlighten me.

P.S Im 29 years old with lots to learn in life but very teachable.

1999 F150 XLT 4X4 no mods except for k&n filter.

 

Altitude reduces mileage as do hills. Additionally, how you broke the engine in and the axle ratio plays a role.

Ken Payne
Ford Truck Enthusiasts Admin

 

It is interesting that you refer to breaking in the new engine as an indicator of how good mpg results will be. In you opinion what is the proper way to break in a new engine? Is it too late for mine? It has low mileage, and it is a dog.

 

[font size="1" color="#FF0000"]LAST EDITED ON 20-Aug-01 AT 08:51 AM (EST)[/font][p]It all comes down to Horsepower and the efficiency of your engine. Gas engines have a theoretical limit on the efficiency (how well they convert gas to heat and Horsepower). Diesel engines operate at a significantly higher efficiency. You can always affct your MPG negatively by making your engine less efficient, but if you think you have an answer to increase the efficiency limits for gas engines, then the automotive industry will make you a rich man (I'm not talking about minor variations here). You, through your driving habits, can elect to use as much of your available HP as you want. Increasing the rolling resistance of your truck by using large/wide tires, using 4wd, increasing the weight, etc will all cause the required HP to go up. Anything that affect wind resistance will affect your MPG. Jacking your baby up, adding grills, light bars, etc will increase your coefficient of drag - and your required HP (that is why race teams spend so much time in wind tunnels). By the way, drag goes up as the square of velocity changes - farm implements don't go very fast and don't really care about how sleek they are. Now you see how towing affects many areas that relate to MPG. Driving up and down hills will use more HP than driving over flat land, same thing with driving with the wind at your back vs fighting a headwind. Imagine carrying a plywood cutout of the shape of the front of your truck on a windy day! How fast you choose to accelerate will affect the required HP and the attendant MPG. A wise man once told me: "If you're gonna work them horses, you're gonna have to feed em". This is why I don't get all the hype about HP increases, unless you are going to use that available HP, why pay extra just to have it available. Having said that, I do have the 5.4L engine in my '99 and do use the HP occassionally to pull trailers, pass other traffic and collect speeding tickets - but 99% of the time, I only use a small fraction of the available HP.

 

As others have pointed out, there are many factors that can affect mileage. Off the top of my head, I can think of these:

- trans type (auto/manual)
- gear ratio (axle, tranny)
- ambient temperature
- altitude
- truck weight
- wind resistance
- rolling resistance (tires, alignment, mechanical drag)
- hills
- driving habits (speed driven, method of acceleration, etc)

And, then you have the question of the engine itself - no two engines are quite the same, and sometimes all the small differences can add up to something substantial. Heck, in our company fleet we have identically-equipped cars that get as much as 25% different mileage.

Improper break-in could be a problem...the automakers officially say that it is no longer needed, but in reality it still is. For a proper break-in, the first 1000 miles are the most important...though the engine is still in the break-in phase for the first 3000-5000 miles. I'm certainly no expert on breaking in engines, but what I do know is that the worst thing you can do to a new engine is lug it (have it turning too low an RPM). Also, it's a good idea to avoid higher RPMs (maybe over 3500-4000rpm) for the first 1000 miles or so, and you want to constantly vary the engine RPMs and not run at a constant speed. One thing which supposedly works very well is to accelerate in gear up to maybe 3500rpm, and then let off the gas and let the engine compression slow the vehicle down - this pulls oil past the rings and helps them seat properly. I did all these things with my '01, and in general ran the tranny one gear lower than I normally would have (4th instead of 5th on the expressway, 2nd in town at 30mph instead of 3rd).

As a vehicle is broken in, your mileage should gradually increase - my first tank I checked was 18mpg, and now I'm in the 19-21mpg range (21 on trips, closer to 19 in mixed driving). Of course, my truck is a 2wd w/few options, which has lower rolling & wind resistance and is much lighter than yours - I'm guessing your truck weighs at least 400 pounds more. You end up paying for all the options at the pump - power windows, power locks, power adjustable mirrors, and that sort of thing all decrease mileage by a fraction of a percent. One of the worst is A/C, but I have that in my truck as well so that isn't part of the difference. Also, my truck has a 3.08:1 axle gear ratio - and yours might be something like 3.55:1 (don't know). However, if you had 3.55 gears you'd thihk that the truck would be faster than it is...heck, mine is fairly quick with the 3.08s (definitely faster than my '91 4x4 w/the 5.0L). Of course, once again that comes down to weight...heavier trucks are slower, which is why you can stuff a V10 in an Excursion and still get outrun by a V6 truck (or a 4 cyl. compact car).

My truck weighs about 4150 lbs. w/out the driver - so, with 202hp that comes out to 20.5 lbs/hp. A 4x4 Excursion with the V10 weighs about 7200 lbs. and has 310hp...which works out to 23.2 lbs/hp. So, by all rights a base-model 2wd V6 F150 should outrun a V10 Excursion pretty easily...and from the acceleration numbers I've seen it does. Your truck probably weighs about 4550 lbs., so you would have 22.5 lbs/hp. It might not be a hotrod, but it should still be faster than most of the late-80's/early-90's pickups running the 5.0L V8...because during that period the V8 was only rated at 150-175hp. Maybe that's what you need to do - drive an older pickup in order to make yours feel faster. :-) I'd loan you my '91, but I sold it close to a year ago...compared to that thing my '01 feels like a Cobra.

LK

 

Thank you for your input,it is refreshing to know that you guys have an honest factual response to my question. Maybe I am expecting too much from my truck,the truth of the matter is that when I purchased this truck with a v6 engine I kicked myself. I couldn't afford to buy new so I was hoping to get a near new F1504X4 with the 4.6 engine. To make a long story short, the sales guy called me up one afternoon with a 99F1504X4 with everything I needed, except the V8. I debated back and forth about a V6, low power,hard on gas,lower resale, until I saw the truck, man this thing was mint, so near perfect it looked as new as a 2001 model. I said i'll take it. From that day till now(owned it for 8 months)it has been a love hate relationship.I love the look,handles well rides real carlike but I hate the performance and the mileage sucks. The dealership has replaced several fuel components(it was burning too rich)which were defective and say there is nothing else that can be done,so therein lies my dilemma "to keep or not to keep". Gas prices here in canada where I live are ridiculous,3dollars and change per gallon, and at 16mpg it can add up. The only speed which I can get decent mpg is 50mph(80kms/hour)(get20mpg) how many people in the real world drive on the highway at 50 mph ? I know of quite a few people that have the newer 97-2001 model and they all tell me the same, low power,low mpg and never again.

 

Some more input for consideration....I have a 2000 F-150 XL extended cab. 4.2L w/ 5 speed manual. 3.55 rear end. 37,000 miles. Use 10-W30 oil. Few aftermarket accessories (tool box, nerf bars, bug deflector, etc). Also, had factory muffler removed and went with a one-into-two "dual exhaust" set-up. No muffler...only cat. converters. It's a little louder than I had wanted but not all that bad. I'll probably wind up having a good muffler installed some day.
Anyways, I do not baby the truck nor do I scratch off every chance I get. Probably 90% of my upshifts take place after a moderate acceleration up to about 2300-2500 rpm. I run 70-75 on the interstate, Occasionally I'll run 80-85 mph but that's not the norm. And now for some numbers....I check my mileage most every tank and average about 18.5-20 mpg tank in and take out. This is a solid consistent average with a varying mix of city / interstate mileage, flat / hilly /etc. All city stop-and-go yields about 16-17 mpg and conservative interstate driving at 65-70 w/out A/C yields about 21 mpg. 75-80 MPH gets me down to about 18-19 mpg. One time I filled up and drove a lot "harder" for 3/4 of a tank. MPG dropped off by about 3 MPG. One thing I have noticed, and it might be accentuated by the exhaust changes made to my truck, I do get better MPG running 65-70 MPH but the truck seems to run better and pull easier at 75-80 MPH. Basically it makes its better power higher in the RPM range. For the record 75 MPH = 2275 RPM in 5th (O/D). The big players in MPG are -accelerating- (remember "drive like you have an egg between your foot and the gas pedal")and -cruise speed- to cruise faster takes more and more horsepower, and it ain't a linear relationship. GAS and Oxygen = horsepower.
My final 2 cents...if nothing is "wrong" with the truck, driving habits are the single biggest variables for similar vehicles in similar conditions.

 

Some of the guys where I work have talked about replacing the O2 sensors in their trucks and improving the gas mileage, one in particular went from 12 to 18 in town in his 6 cylinder. I got them to replace the sensors a 96 mustang when I bought it and my 4.6 liter v8 went from 14 to 14. It did get 28 on the highway. I never figured that out. I did try different driving styles and that did not change it more than 1/2 mpg. I am getting 12 to 13 in the 1997 ext cab 4x4 4.6 liter that I just got (no idea yet on highway miles). I was hoping to get more but had to have that full size truck again...Good Luck

 

[font size="1" color="#FF0000"]LAST EDITED ON 24-Oct-01 AT 01:14 AM (EST)[/font][p]https://www.ford-trucks.com/dcforum/User_files/mil1ion/3bd64d3a74997f69.gif
Seems no one has mentioned one of the obvious ideas about gasoline.
I don't know where you buy yours but, the best gas in Canada is from Shell.
My point about gasoline is : Always buy gas from a BUSY gas bar.
Gasoline has a shelf life of about 34 days.
With our ever changing weather patterns here in Canada,it has an effect on out undergound storage tanks.
Condensation from being Hot, then cool, then hot,etc
Petro-can, Esso, Shell all have special additives according to your general location.
You've must seen our Winter Gas advertised by Shell!

Gasoline in your tank is even more subject to deterioration.

I suggest Never to buy Gasoline from an out of the way Gas Bar.

Watered down gasoline is a prime suspect for "All of a Sudden " less mileage driving.

Dennis

78 F-150 429CJ 465,000 KM.(Original Owner)
68 Mustang 289 Sunlit Gold 80,000 Miles(second Owner)
64 1/2,260 Pre-World's Fair Mustang #8092
64 Fairlane 500 S/C,waiting for a 390 4-Spd

If The Girls Don't Find You Handsome,
They Should At Least Find You Handy!

 

This is probably too obvious, but on the other hand too overlooked as well: Checked the air in the tires?
My 4.2 was getting really sucky mpg also, then one day I checked the tire pressure and found three of them sorely lacking for air! Large tires don't look much different when they're low on air, but man the rolling resistance goes way up!

I would also like to disagree with a previous comment that mileage suffers with an increase in altitude. Not true, as the ECU actually leans the mixture with an increase in altitude, to maintain the same air/fuel ratio in a less dense atmosphere. In fact, for this reason it can be argued that higher mpg numbers can be achieved at higher altitudes, were it not for the fact that since less horsepower is also produced, one tends to put his/her foot down a little further, thus negating any increased mpg.

 

https://www.ford-trucks.com/dcforum/User_files/mil1ion/3bde4f29089d2709.gif
Rebuttle .
What about NON-Computer vehicles.

My Volvo gets 28 MPG on the HWY in O/D.
Elevation 3,325 FT
Calgary AB
When I take it to Osoyoos BC ( Near Oroville Wash.)
Elevation 800 ft
I get 33 MPG Hwy in O/D

4.54 Litres = Imperial Gallon
4 litres = 1 US.Gallon

My truck, 429 gets 17-19 Hwy 60 MPH 2.75:1
Calgary

429 Osoyoos B.C. 20-21 Hwy 60MPH


I say THINNER air causes worse mileage.

TMHO

Dennis

78 F-150 429CJ 465,000 KM.(Original Owner)
68 Mustang 289 Sunlit Gold 80,000 Miles(second Owner)
64 1/2,260 Pre-World's Fair Mustang #8092
64 Fairlane 500 S/C,waiting for a 390 4-Spd

If The Girls Don't Find You Handsome,
They Should At Least Find You Handy!

 

There is no conflict. I was speaking of modern vehicles, most of which are automatically compensated for air mass density by the ECU.

 

I wish I could get 14 mpg out of my 98 4x4 4.6L sc. I do mostly highway driving and get at best 12.5 mpg without laying into it. I also wish it didn't ping like crazy with no repair ideas from ford the past 4 times its been there.