DIC being off

[xchief]

I have read the ansers to my questions about MPG and several others. The answer is always that the DIC can not be trusted when we load any of the tunes. We need to figure the MPG by hand. The old way, Gals into miles driven OK, OK But my next question is; If the MPG is off on the DIC, how are we to know that the speedometer is correct or miles driven are correct? Do the mile get effected or can we assume they are correct?

[ubreathe]

If the DIC is not getting good information from the vehicle there is no way that the information will be near correct. The predator is off about 10% with stock tires.. This makes the DIC show outrageous increases in gas mileage. If you tweak the tire size in the tunes you can get it close. I just made a trip for thanksgiving. The old fashion way i calculated 17.5 miles per gallon. The DIC said 17.8. I set the tire size to 254/69/16. The actual size is 245/75/16. The difference between 75 and 69 is to make the odometer miles match real miles. This gets the predator close. I will post mileage vs stock soon.

[EdMischanko]

If the DIC is not getting good information from the vehicle there is no way that the information will be near correct. The predator is off about 10% with stock tires.. This makes the DIC show outrageous increases in gas mileage. If you tweak the tire size in the tunes you can get it close. I just made a trip for thanksgiving. The old fashion way i calculated 17.5 miles per gallon. The DIC said 17.8. I set the tire size to 254/69/16. The actual size is 245/75/16. The difference between 75 and 69 is to make the odometer miles match real miles. This gets the predator close. I will post mileage vs stock soon.

Is there any comment from DiabloSport??

[mikel]

If the tire size/speedo is incorrect with the Predator, then it was off with the stock tune as well.
The speedo calibration is only changed if you change it yourself, otherwise it uses the factory values from the stock tune.

Thanks

[santa]

Is there a spread sheet that shows speedo calibration changes with tire sizes? My DIC is showing 19.9 MPG on the gas mileage but manual calculations show 17.5, I have not checked my speed with my GPS yet but believe its not that far off.

Thanks

Bill "Santa" Clausen
2005 HD silverado W/banks exhaust and K&N cold air intake

[MABATE]

checking with a GPS is the best way to get it close. You can modify the tire size and double check it against the GPS, say at 60+ mph, that way you can make the adjustments. The reason I say 60+ mph is that at those speeds, they'll show more of the separation of the MPH %. If you get it correct around there, it should be close to being dead on.

[santa]

I checked with GPS--My speedo is dead on and I still am 3-4 MPG off between the DIC and Actual. Kinda sad too cause my BMW DIC is very very accurate!