87 vs. 93
10-12-2009, 11:55 AM
#23
I've logged gas mileage with both EFI Live and my Aeroforce scan gauge. The truck has to use much more fuel with a higher load on it.
On a cable driven throttle body(I can't speak for an electronic one), the amount of air that enters the engine relies on your right foot. Even though the truck hasn't downshifted there is more air entering the engine. The PCM has one of two choices: To maintain the same fuel level and go lean, or to increase fuel to compensate for the added amount of air.
It's the same reason why people see an increase with lower gearing. There is less stress on the engine and less effort to get it moving.
Now obviously we aren't all rolling around with 5.13 gears so there is a point where rpm plays a larger factor than engine load.
10-12-2009, 12:03 PM
#24
My truck drives around at 40 mph in 4th gear, converter locked just fine. I don't have to give it much gas because I'm usually holding speed and barely even have to crack open the throttle body to hold a constant speed. I actually hate 3rd gear lock up. I have it set not to lock up at all until 4th gear.
I watch manifold pressure when cruising 
10-14-2009, 05:34 PM
#30
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