Glad to see your problem is resolved. All of my engines have the 'DC Analog' feature turned off as well. Most of this is caused by 'electrical noise' in you layout wiring. Most layout wiring really is rather substandard, although it might work with DC, DCC will bring out the weak points! Poor electrical connections and loose rail joiners seem the be the chief culprits.
A DCC decoder 'sniffs' the rails to see if a DC or DCC signal is present. If it sees DCC packets, it shifts gears and goes into DCC mode. If there is electrical 'noise' or a lack of DCC packets, it will revert to DC mode and many times will take off at it's last known speed. Our club has the DCC system(Digitrax) set to only send out DCC packets(no 'stretched' packets for DC operation). We suggest that all the member have DC turned off in their decoders. This last item cannot always be done as some folks still have DC operation at home. This has eliminated most of the DCC issues that our club has seen. Our last big issue was losing control of trains with radio throttles. We now use special 9.6v re-chargeable batteries in our throttles. The other 1% of DCC problems are user error(not too much we can do abut that!).
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
It was CV29, thanks for the help. Changed it and it run perfect.
For DCC mode, I believe you want to change CV29 to "34".
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
What DCC system are you using? Have you set (I forget the CV) for DCC only mode? My I/M F7's had a similar problem, it was suggested to set them for DCC only mode, as some systems might stop sending packets when "idle", and the decoders - if they stop receiving packets - will "timeout" and revert to DC operation.
Brad
EMD - Every Model Different
ALCO - Always Leaking Coolant and Oil
CSX - Coal Spilling eXperts
I have an HO scale Intermountain ES44AC and for some reason it changes direction on its own while in DCC mode. It also fails to stop sometimes when the throttle is set to zero. CV's 3&4 are both set to 0, any ideas on either issue?