I'm sure someone on here knows just what the MPG computer uses to get it's numbers...please tell me what it's measuring. Is there a fuel tank level sensor that uses the milage since last filled? Or, does it somehow measure on the fly?? THANKS!!

 

It uses the gas gauge, the vehicle speed sensor (VSS), and a calculation from the PCM.

It uses to gas gauge to determine how much fuel is in the tank. It uses the VSS to determine how far the truck's been driven, and uses the PCM to tell it how much fuel has been burned. With these three it can calculate MPG, and from MPG and how much fuel is in the tank it can take an educated guess at distance to empty. It averages MPG over the last 1000 miles, or since the last time the driver reset the MPG calculation.

 

Thanks Casey...that's interesting! So basically it does run an estimate on the fly throughout the 1000 miles? Wonder why these calculations are so far off for so many people? Seems like it should work pretty well.

 

at stock, the lie-o-meter is actually pretty close. However, once you start to tweak the truck, it gets lost.

 

well mine dont work for crap to begin with, when i bought the truck it didnt work at all, i then read how an fixed it with some new resistors. ever since then it started at 12.9 mpg, then has gone to 13.1 mpg, dosnt move more then that, i tend to avg. 15-16mpg. the miles to empty seems to sorta work, i like how it says i have 15 miles till empty @ 1/4 tank an i go another 70-80 miles an it seems to slowly count down till 1 mile left right before i fill up. I just use it for the outside temp an comp. $400 for a pice of junk from ford if you wanted to replace it...

 

i guess its a toss up. None of my cars/trucks have had one, but my inlaws all do. the times I have used their vehicles on trips, its pretty close. I always hand calc mpg, its just force of habit.

The one that still makes me laugh was my client and his new dury dually. the lie-o-meter kept telling him he was getting 19 but when he hand calced, he found he was getting 15. His thoughts, "I must be driving a lot, cuz for getting 19mpg the diesel sure runs out fast". LOL