Have 1999 reg cab 4x4 with 4.6 auto & 3:55 gear. Just got back from a 2,000 mile round trip to the Flordia Keys. Overall was 16.7 Best was 18.2. Worst was 13.2. The 13.2 was at a constant 85 mph with the cruise control running the AC (Flordia Turnpike). For this setup the best seem to be in the 65 - 70 mph range.

BassDean

 

'Just came back from an Easter-Blast across the state at speeds between 80 and 95 for 80% of the 285 miles.

Gas Mileage was 15.0 (topped-up to overflow both ends on Regular).

(146 days with no 'piston slap' or 'door crack')

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Y2K™

XLT SC SB 5.4L 3.73LS

 

I have a 2000 Lariet 4X4 5.4 auto. I am currently getting between 13.7 -15.2mpg.
Just turned 4000 miles on the odo. When will I start seeing better miliage?


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BikrMan60

 

Bikerman- your mileage sounds pretty normal for a 5.4 4x4 - it should be pretty well broken in by now. That being said, my 4.2 California model picked up a bunch of power right at 12,000 miles - I'm convinced my computer code was programmed to give less than full power at first. I've heard other people say the same thing about their '99 4.2s. They do some wierd stuff with these computers.

My mileage drops into a black hole some where between 70 and 75 - If I keep it below 70, I get at least 2 mpg better on the highway than when I drive my usual 75.

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1999 XLT S/C, 4.2 V-6, auto, 3.55 rear, dark torreador red/harvest gold, bed liner, Sony 10 disc CD, Edelbrock IAS, K&N filter, Superchip



[This message has been edited by dirt bike dave (edited 04-24-2000).]

 

There is something to be said about speed reduction increasing gas mileage. Today I made a 220 mile round trip up I-35 to KC and back. Gassed up and drove with cruise set on 65 mph, had quartering head wind up, quartering tail wind back. Gassed again at same station (same pump) and got 20.6 mpg. I take this trip often at 70~75 mph and best average is 18 mpg. Took me 7 minutes longer each way, but saved me a few bucks. Will duplicate next week to see if this was luck or standard operating proceedure for lower speed. j.b.

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99 SC Sport, Silver color everywhere, 4.2 auto,3.55 rear gear, split bench, stock AM/FM @ 2 cheesy speakers w/Ford brand bedliner. Keep'n stock from the factory because we love it for what it is...One fine ride!

 

Every engine has an optimum RPM range where it operates at maximum efficiency. With my truck (4.6, auto, 3.55) it is around 65 mph (1800-2000 rpm) anything over that and the milage starts to fall from around 17.5 to 15.9 mpg. My 91 T-Bird ( 3.8, auto)on the other hand will get 29-31 mpg at 70 mph. AT 65 mph on the highway it gets 26-28 mpg. Just have to to play around with how you drive from trip to trip and find where that range on your truck is at. Tire pressure will make a difference ( don't exceed max.) less contact patch on road = less rolling resistance.

[This message has been edited by ps398 (edited 04-24-2000).]

 

Well, I just got back from the trip to Denver. Mileage on the way there sucked big time! I ended up fighting a 30+mph headwind/crosswind across most of Nebraska, which lowered the fuel mileage to 14.5 mpg. On the bright side, I made it back on one stop for gas. First tank: 475 miles, 20.5 miles to the gallon at an average speed of 78 mph. (Thank god for cruise control) Second Tank: 440 miles, 22.5 mpg at an average speed of 70-75 mph. The truck pulls about 1900 rpm at 75ish. I guess it just goes to show that it all depends on your particular setup and the weather that day! Whats best for one, may not be best for another... Your results may vary!

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1997 F150 XLT, Flareside Bed, Moonlight Blue, 4x2, SC, Auto, 4.6L, 3:08, Matched cargo cover, Blue Oval reciever hitch plug, 235/70/16 Firestone Wilderness AT's, Sliding rear window, and a bunch of sand tubes (it is winter, ya know...)