Duramax o7 getting 14 around town no hauling what,s going on. Hear so many stories of great fuel milage. Dealer checked it out. nothing wrong. 35,000 miles. Just had it serviced at dealer. Oil change,fuel filter etc. What do i neeed to do short of a tuner?

I think I,ll change Air Filter. Any suggestions

I merged your two threads. As for ideas... I'd try the following:

Change your fuel filter
Change your air filter
Make sure you are using a fuel additive - I use 8 oz of Power Service Diesel Kleen every tank. It helps...
Do you have a lift kit? Getting your truck up in the air reduces mileage.
Do you have oversized wheels/tires? This will increase drag (lower mileage) and throw off your odometer (might be getting better mileage than you think)


Fuel economy is a funny beast - there are so many variables - how you drive, where you drive, temps, etc... that it's hard to pinpoint one specific item.

Answer the questions above and we'll discuss it further... oh, and take a minute and fill out your signature (User CP) and tell us the particulars about your truck. That will help get you a more accurate answer...

Thanks for the Info. Changed fuel filter, waiting on Air filter from dealer. 265/16 tires. no lift kit.
Just started using additive on last fill-up.

try driving like there is a egg between your foot and the go pedal and you don't want to brake it.
Most poor fuel mileage problems are from the driver not the truck.
As for highway speeds, anything over 60-65 will hurt your mileage.
Give it a try for a couple weeks and you will be surprised most likely.
Dan

I get 15 to 17 around town, and 18 to 22 on the freeway. The longer the trip with fewer stops and traffic delays the better my mileage. Using the speed control set at exactly the speed limit helps with consistency. Slope, wind, outside temperature and altitude make a big difference. Going one direction on the same highway can give 1-3 mpg difference than the reverse direction. Fuel quality can differ adding or subtracting a fraction of mileage, as can summer and winter fuel or bio blends. Considering the size and weight of these trucks I am amazed they perform so well. I gained a consistent 1 mpg with XPD Diesel Fuel Improver, but it ain't cheap either. If you have a boost gauge, try keeping it as low as possible when starting off, say between 5 and 7 psi, as more boost = more fuel. In the old days we used a vacuum gauge the same way in gas engines, keep the vacuum as high as possible for economy.

Ive never gotten over 15 on the highway ..

I didn't get good mileage until I added EFILive from IdahoRob. The tuners make the Dmax more efficient which translates to better fuel economy. I was surprised when I got 20.2 mpg at 80 mph on I84 between Idaho Falls and Boise on Memorial Day 2009. FWIW, at 80 mph my rpms are 1850. The best I ever got was 22.7 between Boise and Winnemucca NV. Average speed was 73.

IdahoRob's tow tune which is my daily driver dyno'd 425hp / 770 ftlbs and runs consistent 14.2 secs in the 1/4 mile. The only trans mods are a Transgo Jr., a MikeL cooler and Schaeffer 204SAT synthetic trans fluid.

Rob

2007 d/a truck in gear with foot on brake steering tightens I have to take foot off brake to turn steering wheel. tough parking. anyone else having problem

2007 d/a truck in gear with foot on brake steering tightens I have to take foot off brake to turn steering wheel. tough parking. anyone else having problem


thats what they do... both of mine do this..... gm calls it "normal trait" of the vehicle

With my truck (in my sig) stock around town I saw 12-13 average, after the tuner, 13.5-14.5, with my exhaust (cat delete) and tuner 14.5-16.5.. It all depends on how you drive. To get good mileage you really have to baby these trucks! On the highway after the mods I see about 18-20 depending on how I drive. Good luck!