What Happened???
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New User
Joined: Aug 2004
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What Happened???
Here it is. I replaced the stock air box with an open air k/n filter. After reading numerous posts that the stock air box didn't seal properly and that diesels would get better mileage once you let them breath more freely, I changed the filter. I was consistently getting 14mpg in town and 17-19 on the hwy with the oem setup. After the change, I'm getting 12-13 in town and maybe 15-16 on the hwy. The only other change I've made is new tires, 285/75/16. Thats it!!! What happened to the mileage?? I drive the truck pretty conservatively and don't pull anything(yet). Could someone please help me out with this. I'm actually thinking about trying to find an oem airbox and put it back in!! The truck is an 01 f250 crew cab s/d Platinum edition. I would appreciate any help you can offer.
thanks
thanks
Postmaster
Joined: Oct 2004
Posts: 3,767
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Cold weather, bigger tires, winter fuel. I've read just a few(or 50) threads here on the weather and winter fuel causing a drop in MPG. Add bigger tires, and i wouldn't be surprised if the combination caused the drop. You might also want to do a search here about K&N. My truck had one on when I bought it, and I couldn't get it off and out of my truck fast enough including scrapeing that stupid "filter charger" sticker off the air box.
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Joined: Aug 2004
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Tire size went up one from a 265, air pressure is about 65 I believe, and the fuel is generally fromt he same place. Whats normal mpg for these. I realize that the numbers won't be great butin talking with my brother whos owns a ram2500 diesel, he says he's getting 18 mpg in town. Now thats a totally different engine(6 cylinder) but still thats a huge gap in mpg. I've been thinking about either switching to the napa6637 or the baldwin pa2818 filter. I even asked the dealer and got the warranty speech about removing the airbox. Is their a way to improve the milege??
Elder User
Joined: May 2004
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From: Forest Hill, MD
Are you figuring your mileage by the odometer or going by the overhead computer readout. If you go by the odometer then you also have to consider the speedometer error caused by your larger tire. Your new larger tires cause your speedometer to show a speed that is slightly slower then you are actually travelling so your odometer records less distance then you are actually travelling. This often causes a perceived MPG loss that isn't really occuring. Yes the larger tires will slightly decrease your mileage, due to the added weight, greater rolling resistance, ect. If you are going by the overhead computer, well lets just say they aren't exactly known for being dead on.
Tuned
Joined: Sep 2003
Posts: 491
Likes: 1
I got a similar change in MPG when I moved up to a 285. The tires make a big difference, alot more drag.
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