I have only had my new truck a few days and have only burnt one full tank out of it and my gas milage is bad. I reset the computer for the one tank fill up, and it showed 11.1 as the average and i thought that could not be right. I was not driving the truck abnormally hard or anything, it wasnt much highway driving but not a lot of stop and go either. The truck only has 7000 miles and i know it takes a while to break in a diesel but should'nt my fuel milage be alot better? Could something be wrong with the truck. I remember reading somewhere that the first 04.5's needed to be taken in to get reflashed or something? Could that be the problem and the previous owner never did it? Thanks. (Wow I just registered today and this is my third post with questions on the truck, Sorry guys, sites addicting already )

 

best if you give yourself a few tank full and hand calculate your MPG , your overhead is most likely not correct.

 

And yes, there was a TSB I don't remember the number) for Millage & White smoke on start up. It slightly improved millage, corrected somewhat the overheat computer, altered the shift points for the better and a few other things. Ask your dealer to check and see if all have been done. With mine I was about where you were for a while. I am now at 26000 and get 19-21 Highway and 14-16 around town. These engines begain to drink fuel after 2100 rpm or so. Keep it around 2000 and start using some of the fuel additives, Power Service and Marvel Mystery Oil and see if it helps. It will get better millage just be patient.

 

Actually the mileage issue has been a topic here over and over, and after several of us keeping track of mileage it is clear to us now. Your computer is not wrong and your truck does get crappy mileage now, HOWEVER!. It will get better over time and yes it will take longer than a couple tanks of fuel. I have about 22,000 on my 4.5 and im finally getting about 17 in the city and upwards of 20-21 on hwy. Just give it time it wont happen overnight or even within 1 month, but it will slowly gain. Try towing whenever you can, helps break it in a bit. Have patients

 

I'd check the air filter, and replace the fuel filter, then put a load of some flavor on it and run the snot out of it for 1 or 200 miles before I got too worried about it. Diesels don't like not being able to breathe, and a dirty fuel filter on these will hurt ya too.

 

Thanks guys. I think i am going to get it reflashed with the right tsb code because if does have white smoke at start up. A lot came out today when i cranked it so i dont think it has been corrected.