I have 2004 1 ton diesel with a 6 speed, When I got the truck thought I had a problem with the TPS, never did figure out what was wrong started unplugging things cleaning and next thing I knowit runs good again.

But now I noticed since it running better I do not get the fuel mileage. The computer in the truck saying about 15.5 at 70 mph on a flat road. and every once in a while I get a hesitation like it is missing on a cylinder. also it feels like my boost is bogging down.

Any suggestion?

 

You can't go by anything the computer tells you on fuel mileage. It might give you some reference point if you know your truck well. But I would never trust it to tell me my true mileage. Mine always reads at least 2 to 4 mpg to high.

Fill you tank to the filler neck, reset your trip odometer and run a tank thru it and refill. Then hand calculate it. Then keep repeating. It's the only way to tell your TRUE mileage.

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I think my biggest concern is the the surge I feel sometimes as I am working my way through the gears. Acts like I am in to high of gear or a cylinder did not fire. I don't know, before this 04, I drove a 96 cummins so I am still learning the truck. I have learned alot off this wed site though.

 

I'm not sure about the issue you are describing, but if you do want to save yourself some time a the pump and hand calc your mpg, search the site for the "tank mod". Its a straight forward mod that allows you to easily fill up the fuel into the neck versus the pump shutting off when you can still add (maybe) 1-2 more gallons.

 

You didn’t say how many mile your 04 has on it. But if it is a 305/555 engine and you are getting 15 MPG. You do have a problem. I get 13 towing 20000 and I am way north of 20 empty.

Joe

 

It has 123000, I have only had the truck 3 weeks. This is my third tank through the truck. filled up did the math and I got 15.7, the part that bugs me the most is when you get on it feels sluggish, i'm trying some injecter cleaner and going to change the filter as soon as I can. I read that a injecter could be sticking. other then that I don't know.