LB7 fuel mileage issue

dougoldsii · Post by **dougoldsii** » Sat Sep 21, 2013 2:48 pm

I have a 04 duramax LB7. I installed the economy tune. Before I installed the tune in my vehicle, I checked for latest updates and were none. I have drove 4 or 5 tankes of fuel through and have not had a fuel mileage increase at all. I can feel the program is installed when i i drive the truck. I have a 4" turbo back mbrp exhaust and a k&n air filter. I have a leveling kit installed with LT285/75R16 tires. There are no problems with the truck. I have a buddy that has the same truck that is getting 24 mpg. Let me know what I should do please, thanks

Post by **mikel** » Mon Sep 23, 2013 12:13 pm

best advice would be to make sure the fuel filters are clean, and that the injectors are healthy.
One injector getting drippy/leaky under the added pressure will kill any mileage gains.

dougoldsii · Post by **dougoldsii** » Mon Sep 23, 2013 6:18 pm

All 8 injectors have been replaced 10,000 miles ago. I replace my fuel filter every 8,000 miles. Have you had any other fixes to fuel mileage issues?

Post by **mikel** » Mon Sep 23, 2013 6:31 pm

No, its very uncommon to see the HP gains and not see any mileage improvement unless the speedo was off originally or the truck is being driven harder than it was when it was stock...

dougoldsii · Post by **dougoldsii** » Mon Sep 23, 2013 8:12 pm

I have honestly driven the truck the same as it was stock. I purchased the tuner mostly for fuel mileage. The power increase is a plus. I know im driving a 7000 lb. truck, but I would like to see a definite mileage increase. What do you suggest I do?

dougoldsii · Post by **dougoldsii** » Mon Sep 23, 2013 8:28 pm

I have also programmed the tire size with a tech 2 to the oversize tires. I have also checked the speedo with one of those machines that have the speed limit sign and your speed below the sign sitting on the side of the road.

dougoldsii · Post by **dougoldsii** » Sat Sep 28, 2013 4:56 pm

Any suggestions?

[email protected] · Post by **[email protected]** » Mon Sep 30, 2013 2:27 am

Im having the same problem. I guess the Silverado 3500 lbz was just made to suck diesel...lol

Post by **mikel** » Mon Sep 30, 2013 10:40 am

[email protected] wrote:Im having the same problem. I guess the Silverado 3500 lbz was just made to suck diesel...lol

Not the case, our 06 LLY sees average gains of 2-4 MPG with the tunes loaded, I have seen ever bigger gains on straight highway trips...

dougoldsii · Post by **dougoldsii** » Mon Sep 30, 2013 11:26 am

EITHER HIGHWAY OR CTY DRIVING I GET THE SAME MILEAGE. SHOULD I HAVE DIABLO SPORT CHECK THE PROGRAMMER OUT? LET ME KNOW MIKE PLEASE.

Post by **mikel** » Mon Sep 30, 2013 12:38 pm

it wont be anything to do with the tuner, the truck has to be willing to respond to the tunes. I will stick by either fuel filter, or injector issues leading to no gains...

If you look around the forums, you'll be hard pressed to find anyone else in the same boat.

dougoldsii · Post by **dougoldsii** » Mon Sep 30, 2013 1:41 pm

Would you recommend installing the 85 horse tune and see if that gives me fuel mileage increase? I am running the 65 horse now.

Post by **mikel** » Mon Sep 30, 2013 3:07 pm

Yes, or the 120 with a light right foot

[email protected] · Post by **[email protected]** » Tue Oct 08, 2013 11:32 pm

mikel wrote:
[email protected] wrote:Im having the same problem. I guess the Silverado 3500 lbz was just made to suck diesel...lol
Not the case, our 06 LLY sees average gains of 2-4 MPG with the tunes loaded, I have seen ever bigger gains on straight highway trips...

I agree Mike I have seen a 2-3 increase my mileage since using the DiabloSport Intune. Also, I have seen increases across the board with each tune hand calculated with an app called mileage keeper on my iphone.

dougoldsii · Post by **dougoldsii** » Tue Oct 15, 2013 6:27 pm

With the 85 horse tune installed, im getting 14.5 mpg.

LB7 fuel mileage issue

LB7 fuel mileage issue

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