When all else fails, try a decoder reset. On the D13SR's, set CV30=2 for a reset. It might be a programming glitch, or a bad decoder. By at least resetting the decoder to factory defaults you can see if it's a programming glitch.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Are you sure CVs 3 and 4 are set to 0? It sounds like they have a higher value, and they are the Momentum CVs.
I have used many, many NCE D13SRs, but I seem to have one now that has a weird "delay". The decoder works in all respects, reading and writing CVs and will respond correctly, eventually---
And that is the problem. This decoder (in an Atlas/kato C-424 that works in all respects, clean wheels etc.) has a full 5 second+ delay before responding to the throttle. It will run at the correct speed once it gets itself wound up, and so on, but the delay is weird.
It is not any CV voltage setting giving the problem. It has a delay at all settings.
Think it is a glitch. I wondered if anyone had a similar occurence.