Very strange mileage

[Mark_be]

Hello,

I recently got back from a 1000 mile trip with our 2001 F350 7.3 PSD and experienced something strange.

When accelerating extremely slowly, like when hauling a few loose eggs in the truck bed, I get 10.5 mpg and when accelerating fast, the mileage rises to at least 11.5 mpg. (semi-hand calculated by an iPhone app)

Shouldn't that be the other way around? Could there be something wrong? Any ideas?


Thanks for the info,
Mark


FYI: I was hauling a truck camper to get this kind of mileage.

[85_305]

This isn't the right section for a super duty, this is for OBS trucks.
But are you 6spd or auto? In my experience with diesel trucks, the 6spds like to be ran further out RPM wise, to 2,000rpms or so, to get best mileage. But the autos like to be babied and shift between 1400rpms and 1800rpms. I dont know WHY this is.. maybe because fueling and boost is different between straight drive/auto, but thats what I've come to find out.

[Mark_be]

Originally Posted by 85_305

This isn't the right section for a super duty, this is for OBS trucks.

That explains why I couldn't find my post anymore. Posted in a hurry. I'll repost it in the right part.