MPG Gauge Reads Off of what?
 

So anyone know what the MPG gauge reads off of for its movement?

I am having running issues, posted about that earlier, and noticed the other day that when the issues pop up the MPG gauge jumps all around.

Is it vacum from somewhere, or maybe fuel pressure or flow?

been wondering that myself... mine just dances all over the place..

The mpg gauge is completely electronic. It's value is calculated from injector duty cycle, and the speedo reading.
Ahmet

Mine doesn't dance much... it's related to the throttle position, obviously, but if I keep a consistant speed, it sits pretty still. On a good day, it reads just under 40 mpg at 65 mph. When I fill up, I always calculate my actual mileage and consistantly get 26-29 mpg.

MPG guage? I don't think my car has one...

I don't think all 944s came with them

Early model 944's came with them above the tach, the only late model 944's which had the speedo were the '85.5 and the '86 years.