Who knew little diesels needed a warm up?

[jagged ben]

Just to add, it's not only slow speeds where I see this.  In fact my most objective observations are at top speed, where I start my speed matching.  Almost all locos need at least a couple laps around my ~30"x36" test track oval before the speed more or less stabilizes. 

[sizemore]

While the great scientific debate on lube, delrin and chafing of parts has ensued, I switched out the DN163A0's (Series 3) for DN147A0's (Series 7). There was no hesitation in throttle response, they just crept along on the first notch (01) of the throttle. I then took the old DN163A0 decoder and put it in an early DCC ready GP-40 (pre-sound), and it did not exhibit the hesitation or sluggishness, it just crept along at the first notch.

Inspection of the motor between the GP-40 and the C420, the C420's show a greater skew of the armature. The winds of the armatures are almost indistinguishable without pulling it apart. I then compared it to Atlas GP-9's which had the same skew as the GP-40. At this point I am largely convinced this is a motor difference (not issue) and motor control capabilities of the old decoder. Given the change in decoders also changed the performance I am also leaning towards tehachapifan's point concerning the quality of the decoder.

Thanks All,
The S.

[peteski]

Thanks for the follow up S!

[MILWcoastdiv]

I definitely notice what is being discussed here mostly with older Atlas.  I have 3 Kato F units that have been in a consist for 3 years with NCE decoders, sit for months and start right up and all speed matching is perfect.  Same type of decoder in Atlas locomotives and it seems like I have to adjust speed matching everytime. I try to run them in consist and forward and reverse trim always goes out of adjustment.  ESU decoders run perfectly out of the gate and seem to remember speed match settings perfectly no matter how long they been sitting unused.   In my case, basement conditions, type of locomotives ect ESU is what I'm trying to standardize with.  I'm in the process of retrofitting older Atlas with with V5 decoders now so it will be interesting how the they run, remember speed settings and generally operate.