Everything else being equal...

Dear John,

Everything else being equal,
and assuming that you're asking about running a DCC loco on a DCC-controlled layout,

a decent loco mech with a "flat tuned" DCC decoder should be electro-mechanically capable of the same or very-similar top-speed to a straight Wheels<> Motor wired 0-12VDC Analog version.

As a start, I would reccomend getting the loco on a Programming Track, and reading:
CV2 - Min Speed
CV5 - Max Speed
CV6 - Mid Speed

On the assumption that "basic speed table" mode is enabled,
and everything else is working-as-expected,

I would _expect_ the values to be

CV2 = 0
CV5 = 255
CV6 = 128

this should give an electrically linear speed-curve relative to the "Speed Step",
and tell the decoder to go to "Max Motor Output Voltage" when the Speed-Step is at Max...

...If you're comfy enough, removing the shell should allow you to directly access and measure the ORANGE and GREY wires (the Motor Output wires) when the DCC throttle is set to "Max",
(assuming you have a digital multimeter available, and are comfy using it)

and confirm that the decoder is putting out around 12VDC as-expected...
(DCC Track Voltage is typically around 14V, which after the diode/power-stage of a decoder,
rectifies out to approx 12VDC available for Motor and Function outputs...)

Start with the above, and let us know the results...

Happy Modelling,
Aim to Improve,
Prof Klyzlr

PS  IF however you are actually asking
"why does a decoder-equipped loco run slower than a NON-decoder equipped loco,
when powered on an Analog 0-12VDC layout,..",
well, that's a whole different, but completely explainable story.... check the Search box with terms "DCC VS Analog" for prior discussions...)

Thanks that is what I need to

Thanks that is what I need to start. I have a NCE Power cab and the Bachman Shark nose. At least I can check these things and try it thanks John

I tried and changed the

I tried and changed the settings now the engine won't even attempt to move.?? I'm using A-Track. John

Back to Basics...

Dear John,

OK, this is getting messy quicky, time to get back to basics.

- Bail on any external software. Your PowerCab is well capable of doing the required programmming, and doing it in a way that is compatible with most common decoders on the market. The "Prog/Esc" button at bottom left of your Powercab Is Your Friend.

- I have to assume that you did not use the PowerCab in proper "programming track" mode, which means your ability to Read-before-Write (IE check the value of any given CV _before_ changing it) would be massively hampered.

- Do we have any idea of what the actual decoder is? 
(Brand and Model). If we can ID that, we can likely throw a simple "factory reset" at the decoder to get it back to "functioning baseline", and then work out the speed issue from there...

Reccomend reviewiing the "DCC Shortcuts" card linked here

http://mrhpub.com/2018-02-feb/download/BONUS-DCC-Shortcuts-Card-v1.2.pdf

particularly the "Resetting decoder to factory settings" section top centre of the card...

Let us know how you go...

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Reset time!

Some Bachmann engines came with decoders that do not use as wide a range of CV values as the Professor quoted.  CV5, for instance, may only go up to 32, not 255.  More accurately, a value of 32 in that decoder is full speed, just as 255 is full speed in regular decoders.

Some decoders really do not like being given out-of-range values in their CVs and they just stop and pout.  Hopefully setting CV8 to a value of 8 will reset the decoder and you can start over.

Scott Chatfield

I tried to read the

I tried to read the manufacturer of the board with the programmer and came up with "generic".  The # on the board is H601lx pcb01 rev b it is in a Bachman RF-16 sharknose diesel. John Will try the reset tomorrow

My Bad...

Dear John, Scott,

My bad, Scott (Blinddog) is correct, and it's actually worse than we feared...

1 - Assuming this is running the stock B'mann "DCC Equipped" decoder,
it is very-likely one of the "Lenz cut-down" decoders.

https://tcsdcc.com/installation/ho-scale/1196

http://estore.bachmanntrains.com/index.php?main_page=product_info&products_id=1467

2 - Per available documentation, CV2 (Min Speed) is indeed limited to a maximum value of "31"
https://www.bachmanntrains.com/home-usa/images/44913_Decoder_IS.pdf

3 - Again, per available documentation, CVs 5 (Max Speed) and 6 (Mid Speed) and not included/supported,
so yes, blindly programming values into these address-spaces could result in (?who knowns what?) kind of behaviour, inc "apparent brick".
 

HINT: Using the PwrCab in Programming-Track mode would have given us a clue before any damage had been done, as it automatically reads the current CV value before we get to the step of "nominating the value we wish to program into the CV-in-question"... if the PwrCab says the equivalent of "No such CV or value", then we know we're heading into bad territory....
 

4 - The Good-news is that "CV8 = 8" reset should work, esp if performed properly, direct from the PowerCab, in "Programming Track" mode.

Recipe:

- Connect the PowerCab to ONLY a completely isolated piece of track
- Place ONLY the loco-in-question on the isolated track section
- Power ON the PowerCab

- Press "PROG/ESC" FOUR times
(screen should say "Use Program Trk",
see Pg 36 of the PwrCab manual)

- Press "Enter"

- Press "2"
(Enters "direct CV programming mode"
see Pg 46 of the PwrCab manual))

- When the screen says "Enter CV Num"
(See Pg 55 of the PwrCab manual)

Press "8"

- Press "Enter"
(you have told the system you want to program CV8)

- The system will READ the current value of CV8, which should typically be a code which reflects the manufacturer of the decoder.

- When the screen says "Enter Value"

Press "8"

- Press "Enter"

You have just programmed "CV8 = 8", which should trigger a reset of the decoder.
Rock the loco clear of the track (break contact between wheels and rails for at-least 30 seconds)
in order to "reboot the decoder", and assert the change.

You should now be able to:
- press "PROG/ESC" to EXIT "CV programming mode"
(the PwrCab will return to "normal train-running operation" mode, with full track power)

- select Loco address "3"
(typical default address for factory-reset decoders)

- and retest if you have regained basic Speed/direction/light behaviour...

...now, assuming you've gotten this far, we should be "back to where we began",
with a loco that "basically works", but is not operating at the speed we expect...

...A review of the original product reviews (MR et all) suggest that the loco is slower on DCC than Analog,
but only by a small ammount, (90smph VS 98smph respectvely),
and still achieves a top-speed far in-excess of what most modellers would find desirable.

https://mrr.trains.com/news-reviews/staff-reviews/2008/02/bachmann-ho-scale-rf-16 

SOOOO, what could be causing this particular loco to "fail to fly" at top-speed?

Well, additional Googling suggest that this loco was a partnership-build between B'mann and some other Model Producers, and the average QA accross the production-range may have been "not quite as one might hope". A check for binding and/or excess slop in the drivetrain may be enlightening, as would a possible clear-and-relube of the truck towers. Some models of the late 90's/00's era are known to come ex-factory over-packed with quite-thick "peanut butter" grease, which can manifest as a "slow speed mech". Cleaning and relubing with a sane ammount of quality lube (Labelle, Nano-Oil, etc) can make a world of difference.

There also seemed to be some debate around the time of release (2005-2008?) RE "Break-in time" of such mechs, and the alleged improvements in slow/fast/crawl behaviours after "adequate" break-in periods...
(whether the value/effectiveness of "Break-in period running" is conjecture, confirmed, or just "one guy's opinion" is a long-running debate in Model RRing circles, and this example is no different...)

https://www.trainboard.com/highball/index.php?threads/er-models-sharknose.6970/

https://www.bachmanntrains.com/home-usa/board/index.php?topic=27879.0;wap2

Anywho, do the "CV8=8" factory reset to get back to "works as did out-of-box",
and my apologies for the bum-steer RE CV5 and 6...
(should have taken my own advice and checked the available documentation First...)

Happy Modelling,
Aiming to Improve,
Prof Klyzlr

Software can be useful

John,

While not wishing to contradict the Prof, I wouldn't totally advise you to "Bail on any external software" since it can be useful to let you see what is going on (although I might be a bit biased as the creator of the A-Track application you mentioned you have !!).

After following the Prof's very good advice on resetting your loco's decoder to factory settings using the Power Cab, return the loco to your programming track and use A-Track to read the first 128 CV values (as explained in the "Making a Quick Start" section of the User Guide - you can just leave the Decoder Manufacturer at 'Basic'). You will then be able to see all of the CV values on the screen and can check the speed-related ones as mentioned earlier in this thread (just hover your mouse cursor over any CV and a label will pop up with the CV description).

You can then save a copy of the decoder CVs to your computer as a reference before you try and make any changes. I will be happy to answer any questions if you contact me via MRH or the Contact page of my own website.

Thanks everyone. Did the

Thanks everyone. Did the reset and got the engines running and will leave it at that. They are faster than before. Thanks again John