Eddieblocktheel

Hello all and thank you for looking. Last August I bought an 04 2500. My 98 Cummins just went out and this was my replacement. This thing does not have the power the 98 did. I was getting awful fuel mileage and so I added a bully dog tuner. This showed me that I’m getting only around 10mpg. It never grades me higher than a d in driving. In my Silverado I never get lower than an A.

There are are times where I will get around 13 mpg but that is rare. I took it to. Downs diesel and they replace a fuel pump and said the lifted pump was slipping but to just add fuel treatment every fill up.

It it is still low on mpg. I’m getting 13 mpg. Sometimes it will go up to 18. There are times that it feels like it is dragging and the load will average 20 on the bulldog. A few times when I had to turn sharp it bobbed like it was in 4wd. The light says 2wd.

To add add on to this it doesn’t accelerate like my 98 did. When I tow our church trailers it is really slow.

On the bullydog driving coach, if I barely touch the pedal it beeps like crazy as if I’m slamming my foot on the pedal.

Could this his be the lift pump, the tranny, or torque converter? Any advice will help. Thank you.

westcoaster

You would know if your truck is stuck in 4X4 by the bucking that would occur when turning a sharp corner on hard pavement. (slow speed)


There is no differential between the front and rear driveshafts like in an all wheel drive vehicle.





You'll need to post up some particulars on your truck.





Standard or automatic?


Differential gear ratios?


What kind of exhaust? The fuel economy went up on my '04 when the muffler rusted and fell off. soot had plugged the baffles in the stock muffler and was restricting things considerably.


What size tires?


Air intake? (air filter plugged?)

Eddieblocktheel

I have an automatic with the standard exhaust. the tip in not perfect but still large. the tires are 31.5 I believe from ground to top of rubber. i have a regular intake with a k&n filter. I honestly do not know the gear ratios. I just bought the truck. Thank you for offering advice

Mikeske

I have a 2004 Quad Cab 4 X 4 diesel with the automatic. It gets around 15-18 depending how I drive it. One thing is those tires. I have OEM sized tires LT265/70R17 on OEM wheels. If you have the OEM wheels ditch those big tires and go back to the OEM. If it has a lift ditch it and go back to stock heights. The two biggest things that kills fuel mileage is lifting the truck and putting on oversized tires. The other thing that kills these trucks in my opinion is the K & N filter those things are a gimmick and they do not trap the finer dirt which will get to your turbo and into the engine itself, OEM or Cummins filters are designed to trap the dirt and the filter minder will work. I am running my truck all stock except for better fuel filter and lift pump, EGT gauge and absolutely NO TUNES.

westcoaster

I have a manual shift 4x4 on my (early) '04

I can shift into 2 high and some time later I will feel in "clunk" out of 4x4 when there is slack in the drive line.

Moral of the story: don't believe the 4x4 light. It may not be a true representation of what's happening.

Jack one of your front tires up with the transfer case in 2 high and try to turn the wheel by hand. If the tire doesn't turn (by spinning the drive shaft) your transfer case is stuck in 4x4.

I'll agree with sticking with stock tire size. The size will be printed on the side wall.

The last question: Are you "making" oil? Does the engine oil level go up? could be the sign of a leaky injector.