Loss of highway mpg

[Longshot270]

Originally Posted by cleatus12r

You need to do an ACTUAL test over a few tanks of fuel with actual mileage (make sure your odometer is correct) and gallons used. Watching the overhead display is by no means accurate.

X2, your mileage reports need to be a calculation that you do at every fill up. Even though we are in the 21st century computers are still really stupid. They are only made to appear intelligent.

[demontang]

I checked it on a few ranks and the tune mog if off by 0-.2mpg on average. My last three intown tanks where 13.3, 14.1, and 13.9 with morning warm up for 5-10min. My last three highway where 7.7,5.7 and 6.5 it's terrible. I can hook up my 6000lb trailer and do better in town then my unloaded highway. I have had a dealer look it over and they found no codes etc either. They thought the mileage is reversed cause they don't hear of 14 in town. I'm about to cut my loss and move on to a different rig. I was getting better mpg with 37" tires and 3" of lift cause I averaged 16mpg highway over the mountain pass and down to oregon.

[Longshot270]

At the moment I'm gonna guess that you may have something dragging like the parking brake. In lower gears it won't hurt quite as much. But I'll keep thinking. There is something funny going on.

[demontang]

I'm wondering about my egr system