To see what kind of mileage and performance you're getting would be my guess.Why a full tank, may i ask
or buy a car
^Lots of variables. Tranny, gear ratio, lift/tires, HOW YOU DRIVE etc. It doesnt always come down to the tuner.
And if you weren't a doosh and thread-raiding, you would probably get better answers.
Your idea of "light foot" and MY idea of "light foot" i bet are worlds different.
When I say I 'drive with a light foot', I'm neck and neck with tractor trailers taking off from a red light, I keep RPM's under 2000 (auto... my 6psd I'd shift about 2400rpms for best mileage), I go the speedlimit or 5mph over tops, I coast rather than use my brakes etc. That gets me 18mpg in my truck.
Thread raiding? oh you mean telling the guy with the EXACT same setup as me comin off the same tuner with the same issues as me and switching to the same tuner as i am currently running and giving my feed back about it? LOL Doosh huh LOL light foot means not getting into it hard smart guy. If you want to coast instead of using breaks and drafting 18 wheelers for better mileage have at it but that's not considered "light foot" driving
These trucks are not meant for fuel mileage and for them to be used as trucks not drive like a grandpa...
THE POINT is that I don't drive the truck hard AT ALL meaning I cruise/easy accelerate. And the mileage is around 13.5.. MOST people with my setup who push their trucks HARD get that mileage. It was a general comment made in the direction of the OP so he can take note and record his mileage becuase he has the SAME setup as me.. That is all, derail over
Agreed 13.5mpg is TERRIBLE (i get better than that w/ my lifted truck towing 5k lbs....). I wasn't trying to be a dumbass, I was just giving my input saying that you might THINK you drive easy, but in all reality you dont.
I'd start looking else where; new oil, lubrication of mechanical components, check for boost leaks (huge MPG killer), etc. Hows egt's been? You should start a new thread and try narrowing this down past more than just the chip.