Loading a tune on the PCM does make the overhead off. Recalibrating the speedo for bigger tires won't fix the overhead readout. It will only help with hand calculating fuel mileage more accurately.


Hope this helps~

Diane

 

You can rest it by pushing both buttons at the same time, its not 100% but it can be in the ball park. They read crazy sometimes, as said above best to hand calculate.

 

I ran the oem tune in my 7.3 Excursion for some time, and, with the DP Tuner installed, the overhead claimed better MPG than my hand calculations. With the stock tune, the overhead wasn't too far off my hand calculations.

23-24? Sounds impressive. Always worth going on fuelly.com to see what others are getting in reality with a similar set up. YMMV, as they say...

 

the old bullydog triple dog i used to run threw it way off.

 

They all throw it off , you will have to run a few tanks to get a baseline to see how far off. I just went from one tuner who's chip reading was on average about 3mpg more than what the overhead claimed to a different chip that made the overhead read about 4 mpg higher than actual.
The temp and direction work great tho !!

 

my php tune 6 position has shown no negative affect on my overhead message center. The overhead shows 15.2 and that is a good overall average of my fuel economy. I get 12 when I tow the boat (rarely) and 15-16 when I am daily driving. I always kinda wondered when everyone calls them the lie-o-meter because mine is pretty close to accurate.

 

My lie o meter is off by 1.5 mpg vs hand calculated with php hydra, but with dp tuner I was off by 5 mpg. Don't know what causes such differences.