F-150 mpg problem
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Joined: Sep 2006
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From: GA
Originally Posted by brandonhadnot
i got a 99 f-150 ext.cab 104k miles 4.6L i think it has 3.55 gears not for sure....but i have changed: plugs,wires,maf,all o2 sensors,air intake sensors, k/n air filter, got a tornado fuel safer in intake tube , changed egr valve and sensor, pretty much every sensor on the truck.. have had the cats tested to see if were clogged... which arent.. both intake manifold gaskets had a fuel lean problem at one time.. the truck used to get bout 21-24 mpg bout 6 months ago using 87 octane ...but running 91-93 octane in it now i get 13-15 if im lucky... but as time progressed the truck has lost power... just has no guts.. any solutions..? ideas i'm all ears.. where did the power go how do i get it back?
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From: YUKON ,OKlahoma
Originally Posted by 02SCrew4x4GA
Running 91-93 octane will not help. Higher octane is simply created to stop detonation. This is for High horsepower, high reving engines that need to keep detonation from happending (knocking). Detonation can cause serious problems, but your engine is made to run on 87. Running higher grade fuels will not help. My Lightning had to run 93 because of the supercharger and upgrades.
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You repost your own THREAD? 
here's some answer that might help you.
https://www.f150online.com/forums/sh...d.php?t=254584
here's some answer that might help you.https://www.f150online.com/forums/sh...d.php?t=254584
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Joined: Aug 2006
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From: Troy, NY
Cars that "recommend" high octane fuel probably have the compression to take advantage of better fuel, but will run perfectly fine on regular. The ECU almost instantly adjusts the motor's timing to run on whatever grade without knock or ping. You might see a slight performance gain with the 91/93 but there will be no negative effect with 87. My mom's Acura TL says "premium fuel only" but it's never seen premium gas in it's 130k miles, and still runs like new. Unless your motor has significant mods, you're wasting $5 or so every fill-up.
Shoot, I'll get 20mpg with my '93 3-speed, the 300 i-6 motor on the highway. I just shift earlier rather than later, my revs rarely if ever pass 2500. Of couse it's more like 12 or so around town, but for a 13 year old 4.9L motor I don't think that's bad at all.
Shoot, I'll get 20mpg with my '93 3-speed, the 300 i-6 motor on the highway. I just shift earlier rather than later, my revs rarely if ever pass 2500. Of couse it's more like 12 or so around town, but for a 13 year old 4.9L motor I don't think that's bad at all.
Last edited by RaWarrior; Sep 21, 2006 at 08:17 PM.
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From: GA
Originally Posted by brandonhadnot
hey if my engine is made to run 87 then why in side the driverside door and along the fire wall there are factory labels placed stating 91 octane or higher on the truck
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From: YUKON ,OKlahoma
well how is everyone.. or is anyone alive yet... me im about beat... my brain is like mashed potatoes.. work last night nearly kicked my butt.. so im not gonna be f150ing too much today... i got concrete to pour before i get to bed today..
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From: YUKON ,OKlahoma
woohoo good news... after a full 32 oz. bottle of Marvel Mystery Oil poured in the gas tank my mileage came up so im hittin mid 17's mpg.. but it not where it should be... atleast i know the injectors are definately cleaned out... putting 4 times too much MMO. never hurts to over to it. 
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From: YUKON ,OKlahoma
Originally Posted by kretinus
No offense dude, but reading some of your other posts, I have to ask, did the guy who sold you that give you some lube to go with it?
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Originally Posted by brandonhadnot
that tornado works... and i modified it to work even better.. so im not offended. and the price has been reasonably good.. nothing i have done.. is any worse than anything that other idots have done or asked bout...
The whole theory behind them is somewhat laughable.
You might think it works, but if you had any measureably different mileage, it wasn't because of that BS.
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From: Kentucky
were do you all get your gas i know if i get my gas from chevron it dont last that long i most of the time get my gas at speedway they have marathon gas any one know of a better gas for milleage