I just bought an o4 5.9L 5 spd 3.73s that isn't pulling like it should. tried pulling an 4700 lb camper and was losing major power on slight hills.Had to gear down on bigger hills in 3rd. Even with out a trailer behind it I beleive it should run a little better. You can hear the turbo but it seems not to pull very hard.I looked for cracks in rubber boots and tightened clamps from turbo to intake,changed air and fuel filters. has an aftermarket exhaust so the cat isn't clogged. Any pointers?

 

In 03 and early 04 Dodge made High Output 305hp engines, and Standard Output 250hp engines. There were also SO engines for five states that were 235hp and have a cat. Based on your 5 speed transmition, you have an SO. That's not a bad thing, it just needs some help in the hp department. There is a lot of performance parts available, but you should have some gauges first. A boost gauge and an EGT gauge minimum.

I have the 235hp 2003 model that I bought new. At first it was a slug. But now I have more power than I can use with a couple of add-ons.

 

Thanks for the info. It turns out that my truck is a 235 hp motor, so i ordered a Smarty and will order guages this week.

 

Welcome to the DTR. Have you checked the truck for codes?
https://www.dieseltruckresource.com/...s-t224833.html

You defiantly need gauges. Check the fuel filter also, this can also be a reason for reduced power. Does the truck run ok on level ground? Does it still have the canister mounted pump, or does it have an intake conversion/aftermarket pump?

 

you'll like the 03 when its chipped it will get great mpg and still run like a spotted skunk. mine topped out at 128. not bad for a crewcab 4x4 dually

 

I changed the fuel filter and it runs the same on level as on a hill. I believe the Smarty will take care of the problem

 

The reason madhat asked you if it still had the fuel canister mounted lift pump, was, they have a high failure rate. this could be your source of power loss, and the Smarty won't help that.

I have drove the SO's, thay have enough power in stock form that you shouldn't be having the power issues you are describing.

Another possibility could be that your Rail pressure relief valve is not holding.