KPID is related to Back EMF

K-P-I-D is related to Back EMF.

https://dccwiki.com/Back_EMF has more details.  Surging is often related to the PID setting in the decoder.

. . .

What DCC system ? This could be 14 versus 28 versus 128 speed step issue. This could be a throttle setting, decoder setting.  Digitrax calls this status edit. 

What if you reset the Paragon 2 decoder back to defaults and run the engine on address 3 ?

I know this was suggested in your other thread by Peter Ulvestad who is a very knowledgeable JMRI user and you declined to follow up.  You need to determine if the decoder programming has caused the issue and the only way is via a reset.  Anything other is just a shot in the dark.

Mal adjusted PID  will cause some lurching but not big jumps or leaps, more like stuttering. Resetting to factory default will give you a start in trouble shooting.

Marc

Back to square one

Thank you all for your input.  I have tried going back to factory defaults with minimal success.  While the engine is a bit smoother, the lurching is still obvious.  My second, identical SW7 has the same issue. 

. . .

Looked thru the BLI site for any motor control setup regarding PID and found nothing but the tech reference which provides little to nothing but mention the related PID CV's (112 thru 120) for the Paragon 2 decoder.  The user guide says nothing about them and provides no example of how to setup / config like others do, best example Soundtraxx Tsunami.

https://soundtraxx.com/content/Reference/Manuals/Tsunami/usersguide_diesel.pdf

The Tsunami user guides walks you thru how to setup there Hyperdrive which is PID related.  You might read this and see how you might apply it to the BLI Paragon 2 decoder.

If not BLI would probably be your only source of a solution. 

That or tear out the Paragon 2 decoder and replace it with something more recent.  More recent decoder have an ato calibration of the PID making this easier to work on.   Soundtraxx TSU2 are like this.

Best of luck.

Marc

I know you said you have 2 of

I know you said you have 2 of them doing the same thing.  Are you sure it's not mechanical binding?  Maybe they are from the same run and had issues.  Changing CVs can only take out so much of a mechanical issue, been there done that.

This brings up

The question of how much break in running have you done on these units?  My practice is to run a new engine forward and reverse for about 45 minutes each way at 85% power.   Joe also has some additional things he does to the truck gear boxes.  I do this running on rollers which makes it easy to do.  That usually will smooth out the mechanics.  however, if there is a bind due to flash or grit, then you will need to dig deeper to solve the problem.
As has been said, if the problem is mechanical, the electronics will only help so much.  Good luck.

Break in time

Larry, the engine I'm working with the most hasn't had much break in time.  I'm working on that now as time allows.  We'll see if that helps.  If not, it's back to piddling with the PID settings, which I'm barely grasping.  Someone mentions that it appears to be over shooting the desired speed and having trouble settling in.  That's a great description. 

Capacitors?

Hi,

I recently tore-down a BLI SW7 and was surprised to find a pair of blue capacitors across the input terminals.

I think they're caps, anyway. Why not clip these off and try to see if your BEMF response gets better? I've mostly come across these suppression "filters" on Bachmann stuff and wasn't aware BLI had ever used them. Any time I do a decoder install I remove them as a matter of course.

These came off a Paragon 2 engine. I thought maybe BLI needed the suppression for their Rolling Thunder transmitter but this engine pre-dates any of that.

Good Luck, Ed

paragon 3 NW2

Just had the same issues with my Paragon 3 NW2, spent the best part of a day trying to tame it,i've got it to where it runs ok and revs up at speed step 1 but won't move till step 2,try these CV'S settings the default are way of the mark,i suppose every motor will be different.

CV's 2=4,3=20,4=10,5=140,6=70,29=14,112=0,113=3,114=6,115=1,116=0,118=20,120=26,201=12,203=6,204=1 and 246=128.

Hope this helps