The (re)flash the dealer recently did to correct a battery temp code, also improved my mileage by an average of 2mpg! This is with doing nothing else driving the same route I always drive for hundreds of miles. They said the re-flash would change some other things (they said like shift points for example) - but the mileage improvement was unexpected.
Hurrah for flashing!

 

thats awesome. it's always nice to get an unexpected perk... I assume your mileage is hand calculated... you already know the overhead comp i usually off.

 

Oh yes - I trust that overhead as far as I can throw the truck...But seriously, it does work for comparison purposes only - the magnitude though has to be calc'd the old-fashioned way.
I always wonder when I read how so-and-so got seventeen or nineteen or ?? MPG - are they going by the overhead or the actual hand-calc'd values?
My actual was running in the low fourteens, and is now in the high fifteens/low sixteens. Not bad for stock motor and tranny without any fuel additives, pushing 35's, eh? And that's not all highway speeds, although the overhead indicated that's where the higher numbers were mostly coming from - the route is a lot of two-lanes with a few stops and some curves and hills, and then over Pacheco Pass which is a bit of a climb, along with about a hundred on I-5.
To be honest, I actually was a little worried that the flash in order to get me better mileage leaned it up some - an old gas trick that shortens the life - but I can't imagine the mfr would write a program to do that when there's still a lot of warranty time left that they would have to pay for repairs on...Let's hope not...

 

So if the overhead MPG is off, I guess the DTE is off as well?

 

That just burns my A$$.

I just pulled all the wires for my QZilla chip and took the BDTD program off my truck last night so I could take it in for scheduled maintenance today.

All along with a list (in my head) to have them check the TSB's for the front suspension and the shift points as well as enable the idle up.

And wouldnt you know it, I forgot! [sm=bangbang.gif]

Of course I have already re ran the wireing harness and reprogrammed the truck!

Son of a beach!

 

Since the Overheads are often off in their indication of consumption of fuel, and the error is of a percentage - the error amount of miles they're off when it shows a lot of miles DTE is greater than the error when it shows just a few before it runs dry. (i.e., 5% error at 300 miles is 15, while at 25 miles is only 1.25)

 

I refuel at 1/8 tank or more because I don't trust the overhead. I don't want to be 100 miles or more from nowhere and run out!