2nd Gen Non-Engine/Transmission Mileage computer readout????

[Gary - K7GLD]

How far back does the overhead 'puter in our Dodges go in displaying average fuel MPG - I only reset mine once, right after buying the truck nearly 2 years ago. BUT, the MPG figures increases/decreases WAY to quickly while driving in varying circumstances to factor in 2 years worth of miles traveled. My gut feeling (and I have a BIG gut!) is that at best it is using only the last several tanks, or maybe 1000 miles in displaying "average" MPG - anyone know for sure?

 

[Oil Burner]

Gary,

I don't know for sure, but I do know that I have reset mine several times and it seems to settle right back on the money in a few days which is about 300 miles for me. I would guess that only "remembers" the last 500 miles or so. But what the heck to I know.

-Jason

 

[ntillm01]

I think they operate off of a simple calculation that just keeps adding the current "instant" to the last "average". That's why they settle down after a few miles after resetting. The changes in the "instant" become much smaller than the "sum" of the instants all added up, so the fluctuation goes down. In other words, the average numbers that are calculated (divided) get bigger and bigger as the next instant small numbers get added to the big average number. not sure I'm explaining that right, but...



With that out of the way, we all know that computers have memory (RAM, ROM, Ron whatever). That memory is only so big. Your average numbers must have gotten big enough to trigger a "reset" so it could, again, start storing an average for you. Otherwise, the memory would fill up, it would stop updating the average sum, and you'd be stuck at that number forever.

 

[Gary - K7GLD]

Don't remember anything from the OM, but will check - thanks.

 

[Cummins Cowboy]

my truck has spent 90% of its time pulling a 5k cargo trailer around town It usually get around 12-13 mpg this way. A few times I have reset the average, I did this to see what kind of mileage I am getting without the trailer as normally the average is about right for each tank before I reset it, however each time I have reset it and drive without the trailer I push the button to see the average economy and I know I have been getting about 18mpg for the last 200 miles or so the average always reads about what it was when I reset it. ie around 12-13mpg So I think this feature is pretty much useless on our trucks cause it is still figureing and averaging the miles from before it was reset even though it was just reset

 

[Gary - K7GLD]

Checked the manual - YUP - average MPG only applies to the last 30 gallons of fuel used... So all this time I've been fooling myself that my 19. 6 MPG was the average since the truck wuz new...

 

[Oil Burner]

Samsonite, I was way off. I thought it was longer. Guess I should read the owners manual better

-Jason