Fuel mileage still sucks

[Lead_sled]

I’ve had the truck since March of this year. Was purchased from an uncle who dropped off at the dealership for any and everything.

I’ll answer as much as I can right now, but will take all listed suggestions and go through one by one as I try to find the issue. I’ve hauled these sand boxes and dry vans only. The fuel mileage when I first started doing it was 6-6.5 mpg. So, in the process of these few months, something has changed. The computer has always been a little off as they never 100% accurate, but even the computer used to reflect a similar 6-6.5mpg.

- I’ll check the doser as suggested with disconnecting and checking.
- Yes, I’ve done the EGR tune up thoroughly according to your posted videos twice with new sensors each time.
- I haven’t had the valves adjusted/set since I’ve had it. I would assume the Kenworth dealership did it last.
- I have not done an injector leak down test yet
- I would also assume the EGR valve is the original as it is the green one. Haven’t touched this one yet.
- The pressure test held, so I’m guessing the pipe that runs around the backside of the engine is still in tact, because no leaks.

Engine serial number. 79343994

It’s listed on the valve cover as 425hp

As far as insite, I’ll have to bring my computer back with me next trip. I’ll drive for another 2 weeks, then will take 2 weeks off. So, this will be a pending action item to see what all is shown there.