Bone stock '02 F250 5.4 with 285s and horrible MPG. Is it the tires?
 

Guys,

I've got a 2002 F250 5.4 with 285s on it and it is getting MPG down in the single digits. Is it the tires? Anything else to try? No codes, doesn't smell rich or anything like that.

Anybody make an new y-pipe for this truck? I looked and can't find one? Was thinking about new exhaust from the manifolds back with a new cat and better muffler.

I have a 03 cc 5.4 with 285x75x16 and around town I get 10 mpg and with a mix of highway and town I get 12 mpg. these are gas hoggs.

There is definitely something wrong. I have a 2wd 03 F250 crew cab with the 5.4 and auto that is lifted on 37" tires and I get about 11mpg. I drive up and down he Cajon pass daily.

Try cleaning the mass air flow censor. Also when did you change tye spark plugs last. Finally, make sure your cat. Converter is not clogged.

How bad is bad?

I'm at around 13mpg's around town all the time in my 2012 F350 Reg Cab 4x4 with 3.73 gears and 285-70-18 tires. Sometimes its better, others worse. The trucks mpg's never seem to be good on cold start ups combined with cold mornings. It seems as if the computer dumps lots of fuel in the motor to get things warmed up. Once warm, the engine gets better mileage.

My truck came stock with a block heater (yes its a gas 6.2) and I am going to start using it to see if I can get better mpg's with a warmer engine upon start up.

One thing is for sure, turn the traction control off and put the trany in "M" mode and the thing rips. Lots of power on the upper end of the RPM spectrum ;)

Good luck with the 5.4, I've read several threads about ignition coil packs going bad but not throwing codes. You could also have a clogged catalytic converter?

Actually that's about right unfortunately my 08 f250 5.4 on the dash tells me what average mpgperson is. city or highway seems to say bout 11.5

I put 295/75-16 Toyos on my '02 F350 4X4 3.73 and I'd say they cost me 1-2 mpg in all driving conditions compared to stock size, but really hurt when towing.

Search SPD y-pipe they sell them on ebay and also Mike @ 5star sells them as well..:-drink

I have gibson dual exhaust, SCT by mike @ 5 star in 87 economy, spark plugs changed under 1000 miles ago, cleaned MAF sensor and 265/75/R16 tires and my average for the entire year has been 11.8 mpg. winter fuel kills my 5.4, ive dropped to 9-10 but hopefully with this tuner that will bump it up some. over the summer commuting to work (about 75% highway) i was at 14 mpg. record has been 18.3 mpg on the highway for 103 miles, cruise control set at 68

11-12 in the summer, and 9-10 winter for me. I got that with my old 285s and about the same with my new 35s.

Hey Drey! It isn't the tires. I'm in the EXACT same boat as Drey. Mileage is the same.

I'm talking 6-7 mpg bad!!!

I just bought a new air filter and some mass air cleaner. Well see what happens. I have a 26 mile commute. All city. My 2008 diesel would average 15 on this same commute.

Damn, 6-7 isn't right obviously. Must be shifting right or you would have said. No codes huh and it don't smell rich? Someone will have an idea what to look for I'm sure.

PCV valve been replaced yet?

If its the blue screw in type pcv valve, I've got one I don't need. Ordered the wrong one for my 2003