Everything Longshot just said is bang on. I asked Bill for a tune that would maximize highway economy but still give me good passing performance when I needed it. As far as I'm concerned, he nailed it.
My truck, a 4x4 SCrew with a bed cap and factory tow is probably a lot heavier than yours. I get about 15.5 mpg in highway driving averaged over MANY tankfuls (I use a spreadsheet do do this). And, one factor that has a big effect is headwind. If I'm driving into a headwind at 70-75 mph, it probably cuts my mileage by at least 2 mpg.
Do try the tow tune, and don't "tinker" with it much. I think you'll like it.
One thing you CAN try though if you're trying for economy, is to change the part throttle shift and torque lock points. I reduced mine by the max for all upshifts and downshifts and gear ranges. My goal was to get the truck into the highest gear possible at the lowest speed with the torque converter locked. This has reduced the tendency of the truck to downshift so quickly on uphill grades and of course gets it into 4th gear at lower speeds. There's probably a bit of "point of no return" here, I may have reduced these too much, but I can't tell much difference between what I have and a more mild reduction. It's all about optimizing the engine load for efficiency.
This only effects part throttle acceleration. Wide open throttle is not changed.
- Jack
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