Looks like injector replacement time in 04 2500.

[Babyhauler]

My 04 2500 Duramax that I bought a few months back smokes too much at idle & gets bad mileage. It has 197k mi & had inj replaced about 70k miles ago. I am only getting about 10-12 mpg compared to 9-10 mpg in my 6.0 gasser. Manual calculation vs DIC reading 4-5 mpg higher. I was hoping for better economy from the diesel. It pulls fine.

This week I changed the fuel filter and did the injector cleaning process with the GM inj cleaner. It idled about 1.5 hours to run the cleaner through. I think it runs a little better but it still smokes too much at idle. My 250 mile road trip yesterday only achieved 14.9 mpg while computer was at 20.1. I do not know why the comp is so far off. Maybe excess fuel is sneaking by the inj. It is not making oil as I have checked that regularly.

To prepare for my last set of injectors I have read I need to add a lift pump with fuel filter and water separator and change filters too often. A fuel additive to lubricate injectors. Probably other things to keep it from happening again. I guess I need to run it hard and fast to keep injectors opening fully & not gumming up.

No, I'm not running tranny fluid in it but other tips are welcome. A GM tech will do the swap so it should be right. This is my work truck & dd.

Thanks.