Hi all,

With all the superior wisdom on this board maybe someone can help.

I have a 97' f150 4.6L 4x4 ex/cab long bed. Bought it used a month ago with 48k miles. I was getting 15 mpg mostly city lead foot driving. I got the super chip and got 11 mpg w/ a light foot. Sent chip back for a check up. Last week I put the chip back and also got a flowmaster 40 catback system installed. Sounds great, think I lost a little low end. Did the battery disconnect for an hour after both mods. Just filled up after 300 miles of mostly highway light foot driving 60/40. 12 mpg!!!! What the f*ck is going on here!!!!! All I want is the same milage Im hearing the 5.4l are getting. Is 17 highway to much to ask? What could be giving me such bad milage? Im using Texaco gas.
To sum it up...
$500 in mods
$1.59 per gal premium fuel
30% worst gas milage
No real noticable power diff with both mods

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97' F150 Lariat S/C long bed 4x4 3:55LS 4.6L auto...SuperChip, 40 series Flowmaster cat back.
Colorado Springs, CO

 

Darren Dude -
This gas mileage thing will always be a hot topic. Here's my two cents. Based on my own experience, I think that 17 MPG with the setup you have is asking a bit much. I have a '97 with the 4.6 motor and a series 50 flowmaster. I do NOT have a Superchip. I get about 17.4 MPG with 80/20 driving mostly freeway. This is being mild on the gas pedal. With your truck being a 4x4 (more driveline loss) and a long bed on top of that, I think you'll be hard pressed to get your 17 MPG. There are many other factors of course that affect mileage. I see you live in Colorado which sounds like the altitude is higher. Was your truck originally sold for that geographic location? That can really have an effect. Is your driving mostly flat or are there hills? I don't know what numbers you are seeing for 5.4 motors. I have two friends with that motor and the best mileage they get is 15.5 - all freeway. They both tell me they get down to 13.5 when some street driving is included. Neither has a chip.

This may sound silly but you can adversely affect your mileage calculation by how much gas you pump into the tank after the nozzle clicks off. You need to really make sure you are getting the level of fuel back to as close the same level each time you fill up in order to get an acurate calculation. I can change my calculation by 1-2 MPG if I don't pay close attention to the final level.
Take notice - you'll see what I mean.

The bottom line here is that I think you have to find what conditions will give you the best mileage for your setup and location and then just accept it.

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Black '97, SC with 4.6, 3.55 gears, automatic, 2-4 Belltech drop kit, SnugTop fiberglass lid, 3 chamber Flowmaster muffler, billet bumper grill, fog lights, American Racing 17x8 wheels with 275-60 Goodyear Eagle GT II tires.

 

Your truck sonds a lot like mine! See my post under Engines "4.6 vs 5.4" BTW my friend had a 97 5.4 4X2 short bed, and averaged 20+. But then again, he had put bigger wheels & tires on. I think that affects the odometer and therefore, mpg calculations. Sometimes I think mine could have a chip. I bought it used. Lots of power. No noticeable pwr increase with $200 chip?? I hope you resolve that. Good luck.

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White 97 XLT SC 4.6, 4X4 "ORP" 3.55ls, tow pkg, long bed, Rhino liner, Owens running boards

 

I don't know why you got worse gas mileage with the mods. When you sent your chip in did you check the mileage while it was sent in. If not pull the chip and check it with the chip out. BTW I average 17-18 mpg 70/30 highway/city driving. Also, have you checked your mileage since you posted here. Maybe someone else can help you better.

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1997 4x4 5.4 ORP XLT extended cab Dark Toreador red Westin nerf bars tint HARDER THAN A ROCK AND FASTER THAN A HEART BEAT

 

If it make you feel any better I get 12.4, and 14.6 on the highway. I've just learned to live with it, I realize it's no Geo Metro.

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Arlington Texas (DFW), member of Fordified.
Mudder,Black 98 Styleside S/C F150 4x4 0RP 5.4 3.55ls, Magnum bug shield, Grizzly roll bar,2 Baja lights, 4 165 watt KC lights (I can light up the night with these), Manik grille guard, Westin step bars,Sonic aluminum treadplate 36" tool box, Flowmaster dual exhaust, K/N air filter, 265/75/16 BFG AT/S, American Racing Baja wheels, a Mobil Speed Pass on the back window, a F150 Online sticker, and a Stone Cold sticker on the front windshield. . More to come for the 3:16 machine: Ramsey Pro 8000 winch is here, and will be on as soon as the hidden kit gets here, 4 more KC lights, shocks, and tail light guards. If you would like to see pics, email me at mudder46@hotmail.com or see pics at me and pony's new website www.angelfire.com/ok3/ponysix8, and to hear the exhaust http://www.angelfire.com/ok3/ponysix8/images/T005.wav

 

Thanks guys,

But keep in mind I was getting 15+ mpg before the mods. Would 50k miles on the plugs be the culprit? Air cleaner looks good, was considering the Air Raid system, but I want improved economy.

Any thoughts Mike?

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97' F150 Lariat S/C long bed 4x4 3:55LS 4.6L auto...SuperChip, 40 series Flowmaster cat back.
Colorado Springs, CO