Ok guys you have given me GREAT advice in the past---All of a sudden my gas mileage has dropped significantly ---(I have a 2005 F150 5.4 4X4 Lariat) Being a dumb *** I took it to the Ford dealership because I really don’t know where else to take it. They did a fuel induction cleaning service, reprogrammed the PCM with the latest software update and changed the fuel filter. However the gas mileage still hasn’t returned like it was after I bought the truck. There have been no error codes or Check engine light nothing---I am at a loss. I thought at first it was the new tires I put on but they are the same size that came with the truck—15X65X275 ---I was getting about 15 mpg before now I’m getting around 12 to 13 mpg. Anyone have any suggestions???

 

Are these new tires heavier than your previous set, even though they're the same size?

Is this just one tank of gas, or is constant for the truck now?

Been getting gas at a different station?

 

Mudterrain is right on spot about gas from a different gas station i think. and even if you are using the same station, they could be gettin gas with a higher percentage of ethanol in it. ethanol has less energy then gasoline (let the cows eat corn, not our trucks.)

 

I have been getting gas at the same station for over three years. The tires are the Goodyear Wrangler Silent Armor P275/65R-18 114T OWL are they heavier than the original tires? This is the first set I have put on the truck.HUMM I don't know about the Ethanol I've been getting the gass at the same place for a while---I'll fill up somewhere else next time

 

I do not know what your original tires weighed, but according to tire rack your Goodyears weigh 49lbs. I don't see your original tires be light enough to merit a 2-3 mpg loss. I am serious about you checking with your gas station and seeing if they are using gas that contains more ethanol.

edit_http://www.tirerack.com/tires/Spec.jsp?make=Goodyear&model=Wrangler+AT%2FS&vehic leSearch=false&fromCompare1=yes&partnum=765R8WRATS OWL&tirePageLocQty=%26partnum%3D765R8WRATSOWL
this is the website showing your current goodyears.

 

I had BF Goodrich Rugged Trail T/A P275/65R18 114T ORBL

 

I will check with the gass station--It's Valero used to be shamrock

 

Tirerack, http://www.tirerack.com/tires/Spec.j...e1=yes&place=2
says the Bfgs are only 43lbs. However, I still do not think the 6lbs is a big enough difference. Another idea that came to me is the psi in the tires now vs what was in there.

 

I had the ethanol problem too. It is hard to find non-ethanol gas where I live now, and it drops my mileage by about 1 mpg.

What a waste...

 

what speeds do you drive your truck at?

 

Thanks guys the tires I have now are inflated a whole lot more than the BFGs were. The BFG were about 35PSI the new ones are 44PSI. I checked with Valero and they say that they haven't changed the amount of ethanol level any 10%---so I don't know--I haven't changed my driving habits much I drive mostly Freeway speeds on the freeway and the speed limits---Something has changed and I am at a loss---It wasn't a gradual change I noticed it right away--that's why I took it in to the ford dealership

 

If you ever get your truck back to getting 15 let us know what you did. Since I had my 05 I only get MPG's in the 13's my last tank I got 13.36MPG one before that was 13.78MPG I got over 14 MPG once in the last 3 months and that was 14.12MPG. I have never gotten the 15 city this truck is supose to get as of yet. I have had the truck since early November of 2005.

 

wow I wish I knew what happened---

 

Could it be the transmission?

 

My gas milege has dopped a whole lot could it be the Transmission?