Sudden decrease is gas mileage
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Sudden decrease is gas mileage
Just a few months ago, I acquired a 2004 F150 4wd crew cab, 5.4 engine with 114K miles... I was running ~15.2 MPG in the city and as high as 17.0 on the interstate up until yesterday. Gas mileage has suddenly dropped to 12.9~13.1 MPG in town. Sunday, I changed the oil (myself) adding 6 quarts of 5-20 (first oil change since I have had the truck) but didn't driven it enough to pay attention to the gas mileage... and then yesterday, I had the mechanic add 12 oz of freon to bring it to the proper levels- but I was with him watching and that was the only change made.
So my question is, the oil change and freon were the only two changes... driving habits are the same. What caused my mileage to drop like that?
So my question is, the oil change and freon were the only two changes... driving habits are the same. What caused my mileage to drop like that?
Hotshot
Joined: Sep 2010
Posts: 10,459
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From: RVA
Dirty MAF?
Dirty air filter?
Clogged up fuel filter?
Could be a bad tank of gas. Do you fill up at the same station every time? Might be a different blend that the service station acquired.
Are you relying strictly on the truck's computer for your mileage, or are you hand calculating per fillup?
Dirty air filter?
Clogged up fuel filter?
Could be a bad tank of gas. Do you fill up at the same station every time? Might be a different blend that the service station acquired.
Are you relying strictly on the truck's computer for your mileage, or are you hand calculating per fillup?
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You know what, i didn't even think of the gas thing (the most obvious), (someone slap me)but yes, I did fill up the same night I changed oil.ldn't see 2 MPG variation without a reasonable explanation. The gas thing makes sense. I'll burn through this tank of Wal-mart gas and go get some Texaco (which is what I usually put in it).
Senior User
Joined: Aug 2008
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From: Vicksburg, MS
You may have a higher amount of ethanol in the WalMart gas than the Texaco. I've had this difference in the past when I used Murphy gas. I have a Civic Hybrid that shows a significant drop with ethanol gas. My '04-5.4-3v doesn't show much difference since I reprogrammed it with an update from Hypertech.
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Joined: Jul 2009
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From: Minneapolis, Mn
Mileage
You know what, i didn't even think of the gas thing (the most obvious), (someone slap me)but yes, I did fill up the same night I changed oil.ldn't see 2 MPG variation without a reasonable explanation. The gas thing makes sense. I'll burn through this tank of Wal-mart gas and go get some Texaco (which is what I usually put in it).
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flowerpower
6.0L Power Stroke Diesel
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Oct 28, 2009 04:31 PM
