Fellas, I'm a little stumped. I know we've been a little cold lately "low single digits here last week" but it was cold last year also. I was getting around 14 last year this time with the truck completely stock. The only additions have been a set of 16x8 rims with 265/75/16 tires, and a MBRP catback exhaust. I do have a predator and programed the computer for the wheels but have left the computer stock right now for winter. I did throw a "P0402" but my dumb ass cleared the code so now the dealer doesn't want to see it until I throw another code. Right now I'm running in the 11-12 mpg range, just doesn't seem right...I have approx 22000 miles on her now so it should have opened up a bit but it got worse.

:confused::confused:

when I installed the bigger tires on my truck I lost some mpg. I don't have exhaust but my guess will be that it Will effect mileage. I have got better mileage when i installed the tuner and blocked the egr. my 2c

Something seems wrong. My #2 truck get about 15.5 mpg and I run it from 0 elev to about 1800 foot in 15 miles. IYou can see I also have 265 tires

I've got about the same mileage as you. I'm running a cat-back mbrp also. Never have thrown the 402 code. I'm running a PPE 90hp tune and blocked. You might have a egr going. I'm getting a little better mileage 15.5 mpg, but I'm still running the 245 cookie cutters.

Me Too I Put On 265/75/16 And My Mileage Seems Horrible At The Stock Program . I'll Run Superchips On Tow Tune This Week To See If It's The Same Poor Mileage As Stock. I Really Think Something May Be Wrong But No Codes.

well at least I'm not the only one. I am fishing for an egr problem but it could be the winter fuel. Just didn't seem to get that bad of mileage last year and just going to a 265 from 245 I wouldn't think should make that much of a difference. I was running around 19 on the highway in the summer...I miss summer fuel.

I did throw a "P0402"

Your cat-back should not have caused the P0402.

winter fuel will easily drop 2 + mpg. I wore out my 285/75R16 so I put the original cookied cutter wheels back on (245's) and I think I actually got better milage with the bigger tires at least on the hyw. The rpms were about 300 lower with the bigger tires at between 70 - 75. I just ordered some new wheels and tires 285/65-18 and will check it out then.....

I had the same problem with mine, just block it and be over with it!

I have received a couple of EGR codes on the predator,,thinking of blocking it. I thought i read somewhere that when cold you could just unplug the egr and it would stay closed? Obviously you would have to use the finger stick to prevent a code, or do you?.

When i went to 285 tires my mileage dropped 2+ mpg. i originally ran 255/85's and mileage was much better but due to poor off road ability I went to the 285's.Seems like the width of the tire makes the biggest difference in mileage. Brand new and 245's for the first tank I got 17.9. Switched to the 255's and still close to 18 for another 8000 miles or so. I average right around 15.5 mpg now.
Mods: predator 85hp tune, no muffler and gutted cat. I have 22000 miles now but mileage hasnt changed in the last 10,000 miles or so. If I run the factory tune I lose another 1mpg, towing or not. Added a tonneau cover a while back to and no change in mileage at all.

Towing is when my mileage really hits the tank. My usual load is a 20ft bumper pull trailer (1500lbs?) and my Kubota RTV that weighs 2000lbs. On a recent 1100 mile hunting trip i averaged 10.2mpg running 70-75 mph,all highway. I pulled this same trailer and load with my 7.3 powerstroke f350 crew 4x4 Long Bed with 285's and got 16mpg even running 80+ mph.

Seems obvious to me that the LBZ dosent get near the mileage the earlier models did.I guess more horsepower requires more fuel.!

Wondering if a finger stick and blocker would do anything for mileage?