The wifes 05 is making a pinging noise on one cylinder when accelerating from a light and when pulling a easy hill at low speed. It really sounds like one cylinder. They did a reflash when it had about 1500 miles on it and the engine sounded louder than before. It now has 5500 miles on it and is only getting high 12s and low 13s for mileage. It has one cylinder that you can always hear that is different than the rest at idle and when driving, but it isn't missing. The mileage was around 14. 5 to 15 combo driving. I had the dealer listen to it and they said BAD FUEL. I have aways used HOWS since new and have added cetane boost along with HOWS and no change so I think that this completely eliminates the fuel issue. The dealer also thinks it may have a mild injector issue but told me it would have to get worse before they could find it. I have changed the fuel filter once and it looked great. I listened to an 04 yesterday and it just purred and was quite a bit quieter than the wifes. All the mileage is combo driving with no load?? Anyone have any ideas or sugestions . sorry no profile. . 2005 2500 auto 4wd and 91 w-250 cummins auto