BOY I TELL YA 2006 LBZ 8000 MLS. RESET AVE.ECON ON WHEEL WITH TO THE RIM FUEL. STILL BEST GET IS 14 TO 15 MPG. ALL STOCK BUT 285 TIRES. IS REALLY GETTING BETTER THAN IT READS CAUSE OF TIRES OR IS THIS BOUT RITE???????:rant:
Buy a tuner, my MPG increased from 15 to around 17-18. Im running a Power Pup. Plus you will be able to compensate for the 285s by using the tuner. Another bonus is the ability to raise the speed limiter. Mine is now set at 120 mph. Also try hand calculating the milage, Ive found that the DIC is usually off. Although that could be the tuner causing it. But its worth the $400 to get the tuner.
285x75 tires will throw off your milage by 8%. Take the milage and multiply by 1.08 then divide by the number of gallons you put in at the pump - so to answer your question it will be better than the DIC reads when you have larger tires.
thank ya'll yea man i think im gonna wait on the edge tunner. only cause that wat most of 'em run here in ther truks and they like'em alrite. bully dog seems to have some good reports though. thanks again
Many (if not most) of our DIC's are never correct even with stock tires.
Mileage in these trucks is inversely proportionate to speed - the faster you go the worse it gets, and quickly. 55 to 60 highway on cruise gets my best mpg. 65 on cruise on level gets slightly over 20 mpg on my 06 overweight D/A (9200 lbs unloaded) while 70 drops me down to slightly less than 18. 75 drops me to 16, and balls to the wall drops it to 14. These are measured mpg, not DIC. Larger tire size also hurts mileage. 245 will pull the above mileages and 265 will come close. 285 will drop at least 1 to 1.5 mpg, and 295 will drop it over 2mpg. All highway mileages. Stop and go in town seems to drop mileage to at least 3 mpg or more than highway. If you want good mpg, stay 265 or under in tires, and shoot yourself in the right foot twice. Once to slow down, and the second time is to help you to remember.
My mileage was crap too until the dealer messed up my ECM and they had to replace it with a new one. It was a different part number than the original one, and the truck since then runs stronger and gets better mileage to about 18mpg highway/city.
A forum community dedicated to Chevrolet and GMC diesel truck owners and enthusiasts. Come join the discussion about duramax engines, performance, builds, modifications, classifieds, troubleshooting, maintenance, and more!