Just got back from my Vegas trip and on the way there I got 11.8 mpg going uphill and against the wind. Coming back downhill and with the wind I got 13.2 mpg. Not too happy with the outcome, but it was slight improvement from before.
Are you running off road tires? Brakes dragging? Plugs need retorquing? Lead footed?
@jhartz - Before I forget, THANK YOU. You're giving me great suggestions.
I'm running Goodyear Duratrac 255/55/19 on 06' OEM Range Rover wheels (adventurous weekends) or 265/35/22 Nexan Roadian HP 102V XL on Marcellino Kensington 22" (city or classy days), no brakes dragging (EBC green stuff pads and rotors checked), I changed out the plugs last 6k with new NGK Iridiums ILKR6C-10 and decided to switch to Denso 3444 Long Life Iridiums (way better than the NGKs) and torqued to specs 15 lb-ft (from what I remembered), and I feather the gas where the pedal never reaches half way down the floor.
For the tires, yes the Duratracs are off road knobby tires, but the diameter is slightly bigger and does really well on-road too. The Roadian tires are pure street tires and is about 0.7" diameter smaller than the Duratracs. With that said, I actually get slightly better mpg with the Duratracs when I first got them on (I ran the same mpg test over 3 fill-ups). Back then it didn't really matter which set of wheels/tires I had on, I got over 16 mpg. Something degraded somewhere and I need to look for it.
I'll check the plugs again, and torque them down to specs.
The fuel trims are in these ranges after 3 point in time captures with Terrafirma iCarsoft i930:
STFT - Bank 1 -1.6% to -4.7%
LTFT - Bank 1 -6.3%
STFT - Bank 2 -0.8% to -4.7%
LTFT - Bank 2 -6.3%
My guess your intake valves are gummed too.
@stufrowin - I'll try spraying CRC valve cleaner into the TB a shot.