Jerky Downhill Performance.

[torikoos]

It may be indeed the set up of your decoder that could help solving the problem if you have done the gears already. A P2K has slack, but no more than an Athearn BB drive, probably less than that. It may have to do a bit with torque control etc, as you say uphill no problem, because the engine is straining continuously. you'll need to play with the settings that are in the CV's in the 200's somewhere (forgot which numbers at present). If you have decoder pro software (JMRI) then they'll be under the Advanced tab. Anyway, they have to do with the several bands of the speed control, PID basically. There is a basic set up procedure in the manual , oh heck, I've just found the thread where I helped someone else set up a Tsunami, here's the quote:

A Tsunami has CV's for (technical bit) Proportional, Integrator, and Derivative (PID) controls. Additionally, you can change the sample rate (the amount of times per second the decoder checks the motor responses) between 31 and 2 milliseconds. These factors had a big impact on how my loco runs. It does take time, but check it out if it's possible with your decoder. It is worth it.

good luck , Koos.

PS: The link to the full Digitrax decoder manual is here: <!-- m --><a class="postlink" href="http://www.digitrax.com/ftp/Decoder_Manual.pdf">http://www.digitrax.com/ftp/Decoder_Manual.pdf</a><!-- m -->
It is more comprehensive than the one shipped with your decoder I think, it describes a lot of functions, and not all will be applicable to yours perhaps. Check the manual of your decoder to find out which CV's it supports, and then check this decoder manual from this link, to find how to set it up. Hope that helps.

Koos