I just took a 1400 mile trip to Indiana and back, and I averaged 16.5 mpg going a steady 80 on the Interstates. I'm not a good comparison to a stock truck, as I have a supercharger, upgraded fuel system, and custom tune, but this is about the best I have ever gotten, even from before I had the supercharger.

 

Screw drivin it easy and might as well have fun as it costs a lot to fill these beasts anyway.

 

I have been averaging around 13.5 ttp 14.25 here lately so that is about right. It goes up n down. I used to get better like around 15.5 but not lately. I dont know if its the gas or what.

 

Babyhauler, and for those of you getting "poor" gas mileage, I put that in quotes because these are full size V8 trucks, although I have to agree 13-15 seems on the low end compared to what I have read here, anyway, have you pulled your spark plug wires away from the aluminum air conditioner condensor? There is a very informative thread regarding this somewhere on this board. Seemed to be the holy grail from the responses. Apparently, the aluminum canister interferes with the plug wire conducting the spark resulting in poor performance, at least on that cylinder bank, hence you are mashing it to compensate. Just a thought.

 

If you're getting the same mileage beating on it as taking it easy, you may need new O2 sensors. The O2 sensor monitors your A/F during light cruise and adjusts it for optimum mileage. During heavy throttle applications, it will ignore the O2 sensors and revert to a certain map depending on MAF voltage, TPS voltage and RPM.

BTW, I just got my F150 yesterday. an '02 Dark Grey Sportside 2wd with 5.4L to tow my other toys...

 

i average about 19-20mpg on the highway on the flat texas panhandle. In town i get around 13-16 if i dont run the truck hard. The thing that amazes me is that the truck has over 320,000 miles on it. That is on the stock motor as far as i know. I bout the truck with 280,000 miles on it. the trucks a 97 4x4 5.4. Its a great truck

 

Heh, yeah...my dearly departed Mustang's gauge didn't budge till you'd used about 4 gals, then it moved in the space of about 5 minutes driving from F to 3/4 (16 gallon tank). My Bronco now is the same way - use about 4 gallons, then it starts to move down to 7/8 in about 5 min, and levels off to 'normal' after that.

 

I get 19 to 20 mpg on the flat highway with the 5.4 2wd and don't even want to know what I get in the city. Stop and go driving always kills mileage. Like you I have slightly larger than stock tires, which helps highway mileage slightly. At the same time, being slightly over-geared may hurt city mileage just slightly also. It all comes out in the wash.

 

Don't know if this will help but, My wife has an 02 mountineer. We run 89 octane in it since we bought it, got 19 mpg. When gas skyrocked, we started burning 87 and we started getting 15.6mpg so better gas definately helps plus its so much cleaner for your engine. Now we are back to buring the 89 and the milege is slowly climbing it's back up to 17 .8 now.

 

This last tank would be an average normal driving pattern that matches my previous months w/ out any type of road trip as the last 2 tanks.
14.06 mpg of driving hard & fast. More fun driving like this. Easy,slow driving & I barely get 14.5/15. Something must not be right.
Can I get it "scanned" or checked to see if the comp. is communicating correctly w/ the sensors?
Should I clean the MAF & try that a week or buy the front O2's & see what that does?
Just trying to document & take it one step at a time.
Thanks

 

Keep in mind that your odometer is probably off (unless you or previous owner changed the setting) because of the larger tires. What was the original size, 265/60R17? Check your driver's door sticker or the fuel door for the OEM size. Assuming thatis the original size, you are actually getting an extra mpg.

Cleaning the MAF sensor is easy and cheap. Do it first.

 

It is a 2wd SuperCrew w/ stock 275/60-17 tires as shown on the sticker on the door post. I shall clean the MAF this weekend.
Thanks

 

CA gas sucks, so I always get worse mileage here. I was in Vegas a couple weeks ago, where the gas is slightly better. Filled up and ran the entire 320 mile trip home with the cruise set at 75. Mileage worked out to just a hair over 16.5. I figure that is as good as it can get at that speed. 2001 Screw 4x4 5.4.

 

babyhauler,
I think your truck's behavior is normal. I have an '01 SC 2wd 5.4, and it gets 15 mpg whether I beat on it or not. It's amazing how little difference it makes, city, highway, loaded, unloaded, doesn't matter. I don't do a lot of sitting in gridlock, so that helps. I agree with the comment about lower interstate cruising speed helping, but just don't like to drive slow. Regarding the O2 sensor-it's possible mine is bad but I doubt it, truck has less than 30,000 miles.

The 5.4 is a great engine with amazing torque. I hauled 850 lbs in it last weekend, and could barely tell it was there.

Too bad you didn't get a chance to check out your mileage before all the mods. Some mods can hurt mileage, others help. For example, I suspect that the stock exhaust could be better tuned for lower rpms, where you spend most of your time. It isn't as simple as taking away restriction and increasing mileage. If the stock exhaust was that restrictive, it wouldn't rev past 3000 rpm.

Saying that higher octane gas helps mileage is a generalization, and not always accurate. Higher octane fuel in some areas has ethanol where the 87 doesn't. Ethanol leans out the mixture, and won't do any favors for your mileage.

The acetone thing is a joke, don't even go there.

Increasing tire pressure near the max rating on the tire itself will give you better mileage than using the lower pressure recommended on Ford's sticker. More pressure equals rougher ride though.

 

Update:
14.26 on the 15th, then cleaned the MAF w/ electronic cleaner. Seems to run the same.
Next tank dropped to 13.3 on the 23rd. I do not think I drove any harder or sat in traffic more than normal.
I should be able to install O2 sensors this week, after this tank.
This cool weather last week helps to pep this thing up!
Hope everyone had a good Thanksgiving.
later