proper BEMF programming

[Dupesy]

Hi all, I'm hoping someone could point me in the direction of some solid information regarding programming BEMF settings.  I've been working on installing decoders and speed matching engines, and have been finding some engines have surging through some or all of the speed range, which I'm naively presuming is related to BEMF.  Some of these engines had old decoders in them and ran quite well, but now have the surging with new decoders. 

[jdcolombo]

It would be helpful to have some more information.

1.  What brand and model of decoders produce the "surging"?
2.  Virtually all DCC decoders have a way to turn BEMF off.  If you do this, do you still observe surging?
3.  Is the surging apparent when the engine is operated alone or does it happen only when in a multiple-unit consist?
4.  What speed range does the surging occur at?  Slow speed only?  Mid-range?  Everything?
5.  Are you using a 3-point speed table for your surging engines or are you using a complete 28-step speed table?

The answers to the above questions would help pinpoint your problem . . .

John C.

[Dupesy]

They are all Digitrax, either DN163A0 or DN163A4. 
I have not yet tried disabling BEMF.
Engines are operating alone, while I'm working on adjusting the speed table.
Generally it's at the low end of the speed range.  I do have one that surges at the higher end, which I have set at 40 SMPH.
Using the full 28-step table.

All of them have been given run time to break in, and the decoders are the newest versions. 

[peteski]

Yes, disable BEMF and see how the loco runs.  We had a similar issue with friend's new SDXN167 decoder.  We couldn't get it to behave well, so he finally just disabled BEMF.

[Dupesy]

I'll give that a shot.

And Peteski, while I have you, I have not been able to track down any usable info on MBTA's bilevel coaches for you.

[peteski]

I'll give that a shot.

And Peteski, while I have you, I have not been able to track down any usable info on MBTA's bilevel coaches for you.

Thanks!