Quote Originally Posted by Aepozzi View Post
Well I think I finally figured this transmission out. There isn't anything wrong with the trans at all. It appears the 2003 duramaxes are rated for 500 ft lbs torque. I re-programed the computer for an additional 80 hp which would be aprox an additional 150 lb torque putting the truck at 650 ftlbs of torque. That's more than the torque converter can handle.

As I stated before I pull a big heavy trailer. It weighs 13,200 lbs empty. I figure I load an additional 2,000 lbs that puts me at 15,200 lbs.

I must say with the additional hp and torque the truck sure did perform well. I guess I need to upgrade to a 2007.

Thanks to all that replied. I appreicate it.

Andy
The holding capacity of these transmissions can vary from truck to truck. I've got guys towing with my 100HP tune with great success. It's all about how the tune is written and how much "lying" is done in the tuning. The TQ needs to be limited to the 600-650RWTQ range which is well above the numbers being thrown around here. For some reason I don't have the 50HP tune plot posted, but it's very close in fact people often have a hard time knowing which tune they are on by feel unless they floor it. In this case, the TQ is set to be strong and flat without spikes. The lesser tuners tend to dump fuel and create a rush or TQ spike which is what kills the trans.