Speed control runs in a wave.

[farren]

I’ve noticed my Bachmann LNWR 2-4-0. Seems to be running in a wave. 
 

Sitting the speed at 1 model runs roughly half speed then slows down only to speed back up in a wave. The higher speed the wave gets less, right up  full power speed step 28 model runs almost at a constant speed. 

The decoder is a Bachmann 21 pin and the controller is the Gauge master dcc controller. 
 

I have done a reset CV 8 to 8. With no change. Any ideas welcome. 
 

the track is clean all other locos run normally. 

Edited June 21, 2023 by farren

[Crosland]

I would be looking at Back EMF settings, it sounds like the control loop is out of kilter, but I know very little about this decoder.

 

If you can disable BEMF, try doing that to start with.

[RAF96]

Try resetting the controller as well as the decoder.

You could also consider fitting snubbers to your track power bus.

 

Edited June 23, 2023 by RAF96

[farren]

Well I can’t find how to reset the main controller even if it’s possible. Other than turning it on and off. But I’ve set the emf cv to 0. Runs perfect now. So I’m happy with that. I might play with the settings another day but for now it runs properly. Thank you for your help.