I've been tracking my gas milage since I bought my '99, SC, 4.6l in January of 1999.
The milage started out about 15.5mpg and rose to 17.5mpg in June(Assume rise in mpg due to break-in). Now as the weather here in Michigan has gotten colder, the milage has steadly decreased to 13.5mpg. The dealer ran a diagnostic on the engin and said the results were in spec.

Any suggestions or have others experienced the same.

Thanks for the input.

Bono

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[This message has been edited by bono (edited 12-29-1999).]

 

I've been tracking my mileage too and went from 17.4 to around 16 when it got colder. We don't have the big temperature drop of Michigan though.

I hadn't thought about it being weather related.



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99 Lariat Normal Cab 2WD 120"WB 5.4 3.55LS Tow
Dark Toreador/Gold Line-X
raoul_oba@hotmail.com
F150's of Virginia
Just cause we're from Virginia don't mean we're(well, you know)

 

One thing we have in winter is oxygenated fuel to reduce emmissions. This causes lots of people to have reduced mileage. This stuff is not as good as it claims in my opinion. Your O2 sensors try to make the A/F mixture correct, but since the fuel is screwy it needs more to get the so-called stoichiometric ratio programmed into the EEC. You burn more fuel. Is this good for the environment. Its all crap.

birdman

 

I experience the same thing here in Colorado. I have 2 theories:

1) The oxygenated fuels. With mostly-newer vehicles out on the roads now, oxy-fuels are worthless and expensive (due to the extra taxes and extra costs to put the additives in the fuel).

2) You tend to idle your vehicle more in winter (warming it up before work, after work, etc.)

 

I have the same thing happening here in Minnesota. I go from about 18 mpg to 14 mpg in the winter.

I tend to believe the difference is in the extended idling when warming the vehicle up at cold starts and slower, less efficient travel between point A and B because of bad road conditions. As for the oxygenated fuels, I don't think that has too much to do with the difference, since I use those fuels on occasion in the summer, without a 4 mpg drop in fuel mileage. Maybe .5 mpg, but thats it! Just my 2cents ...

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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 300 lbs of sand for traction.

[This message has been edited by gopher (edited 12-28-1999).]

 

Dr. J's diagnosis..........we must be driving trucks.......nothings wrong.

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The Midnight Flyer
'99 XLT SC SB 4x4 5.4 auto 3.55 ls

I'm not driving fast.........I'm Flyin Low.

 

Hi Bono:
Your 4mpg drop is quite normal. I live in norther Alberta (Canada) and you should see my drop in mpg. I have a F-150 and a '95 GMC with a 350 engine (have been tracking my mpg since day one). In the summer I am getting around 14.5 mpg in the City, now in the winter I am down to 8.5 mpg. As a matter of fact the Canadian EnerGuide says, that at 32F the fuel consumption increases by 8% and at -22F 30%. When combined with short trips and warm up idling this can increase to 50%!!! There you have it.



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1999 XL S/C 4x4, 4.6w, auto, LS 3.55
XL Appearance Group (Polished alloys, 40/60 bench, colour-keyed bodyside mouldings)
XL Value Group (Air, AM/FM Cassette)
Tilt & Cruise

 

My 98 chevy ext-cab Z-71 W/5.7 does the same thing. During warm weather monthes I average 15-17 mpg. During cold ones average is 11-15 mpg.

 

I have a similar decrease in my mileage during the winter months. The colder air makes my truck a lot more responsive so my decrease is probably due to my changed driving habits. Just can't help myself.

 

add me to the "me too" list. My truck goes from 14-15 mpg to a 11.5-13 mpg in the winter.

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97 F-150 4.6 auto, 4x2, 3.55 LS, WMS Velocity tube, K&N, Dynomax Super Turbo exhaust with Echo tube.
Oh yeah, it's Oxford White with crome wheels, Legacy shell & custom grill!

 

I think it's the oxygenated gas, too. Someone tell Bill Clinton and his EPA to get the hell out of my gas tank!
Next thing you know they'll be messing with the enzymes in the beans I use in my chili.

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97 F150 Lariat 4X4 Ext. Cab. 5.4, AT, Tow Pkg, bedliner, white/grey 2tone w/ grey leather, Fact. CD changer, Gibson Side Swept, K&N, Bosch Platinum +4's,Michelin LTX 265/70 16, Both doors cracked, Piston slap quieted by Mobile One & Slick 50 Synthetic.

 

I thought something was wrong with my truck as I am included in the decreased mileage club too. I just put a Superchip in my truck and thought that was the reason along with the hot rodding that comes with the chip. I guess thats what you get with driving a 5700lb truck, 11-12 mpg during the winter and 16-17 in the summer.

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'97 F150 Red/Silver Lariat, SC, 157" wheelbase.
Factory Equipment includes: 4x4, 5.4L, Automatic, 3.55LS, Grey leather, Power bucket seats, HD Tow package, Rear sliding window, Ford bed Liner, electric shift on the fly.

Aftermarket additions/modifications: Superchipped, Bug deflector, Window Drip edge guards, Sony 10 Disk CD changer, Chrome Nerf Bars, K&N Air filter, Air box Modification, 2-1/2" True Dual exhaust with chrome tips out the back, 36" glass packs, 265/75/16 Michelin LTX A/T's, custom rear spring pack, cranked torsion bars, Extang Tonneau cover.


Future additions: Hellwig bar, tinted front windows, still looking for "good" floor mats?.

 

I've had my truck for almost three years and ditto on the reduced gas mileage. Great theories about the oxygenated fuel! I never thought about that.

I hypothesized it was due to the below freezing temps not allowing the engine to quickly get to an effecient operating temperature.

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Warren's Web Page
\/\/arren B
"It showed us that we have to care for each other, because if we don't, who will?"
- Susan Ivanova, Babylon 5

 

I'm sitting at 7,000 miles now. I was getting 14-15 mpg. Last tank was 2/3 highway (against a strong wind) and I got 13 mpg. The tank before was all city and I got 12 mpg. I'd guess that the temp has dropped about 30-40 degrees since I was in the 14-15 range.

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1998 F-150 SC 4X4, 5.4, ORP, Red clearcoat, K&N, Chrome push guard, roll bar & tube side steps, Smoke bug guard and tail light covers, Black bed mat & Ford mud flaps.
www.wrtc.com/oldbook/Truck5.jpg

 

Your gas mileage decreases because the air is more dense during winter. You'll remember from science class that when things get cold they contract. The same applies for air, it contracts, or becomes more dense. Because of this, more air can get inside your engine. Your computer wants to keep the air/fuel ratio the same, so if you drive the same style and idle the same amount, but your engine is taking in more air, what happens? You burn more fuel.



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-cm