LMM Fuel Economy

[JohnC]

Diesel fuel 3.399 gal = very expensive

Ah, for the good old days!

[prairiewind]

I have owned a 2002, 2004 and now 2008 3500 HD. Got 17 to 19 in first two. I have 72,000. on the 2008, got 17 when first purchased, now 12 to 14. When I take to dealer and they reflash I can get 19, this will las for a few tanks of fuel then back to 12 to 14. I can put my auto zone tester on and there will be no codes, I reset codes, even though there are no codes, and I go back to 18. I would like to put an edge cts and an exhaust brake on but would like to figure out what is wrong before I do anything. Dealer has no idea.

[DieselDavy]

Are you hand calculating?

[prairiewind]

Yes, mostly, I pretty much use this truck for trips, I can look at the fuel guage and the milage and tell what is going on. Last summer I had the fuel system cleaned and they reflashed at the same time. I made several trips pulling a 4 horse slant and got 13, a couple of months later I made the same trip empty and got the same, 13. I went back to the dealer and another reflash and back to 17 to 19 depending on how I drove. These trips are over I70 from Denver to Page AZ. I also have a 30' Montana and when everything is running right I can get 10 to 12 when in my lame mode I get 6 to 9. When I started resetting my codes, even though they don't show up it doesn't make a difference right away but after a couple of hundred miles I can actually feel the truck respond. The truck goes from sluggish to very responsive, you know exactly when it happens

[prairiewind]

I was sure hoping someone could let me know if they had the same problems, have tried to reset, anything.