It's just a guess, but if you are doing everything 'correctly' but one thing, that one thing might be leaving BEMF enabled. Sometimes the decoders sense the other decoder's motor resistance and the two begin to fight each other, or work at cross purposes to each other.
I may have misunderstood your description. If so, sorry...
-Crandell
BEMF stands for Back Electro Motive Force. The decoder in essence senses the speed, and current that is keeping the motor turning and adjusts it electronically by giving it more or less power to keep it turning at the same speed. This happens thousands of times a second. When 2 or more locomotives are hooked up with BEMF they can and often will fight each other to keep the motor spinning. It is not uncommon to to see one spinning its wheels or even dragging one along. BEMF is disabled in the decoders. Some decoders can disable BEMF automatically when consisted if configured right.
Your issue may stem from the way your units are consisted. I don't know about the Zephyr but on some systems if the memory is full you will have to delete some older consists before entering new ones. This happens on our clubs Lenz system. It holds 999 consist addresses and if you happen to not delete an address it keeps adding up until it will not take anymore. These are not separate addresses 1 through 999. It is possible to have 100 consists with the same address. Each one will be different with subtle changes. So every so often we do a complete reset and dump the memory.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
It would help a lot if you would tell us which decoders are in them, especially if two different brands and types are involved.
Welcome back.
CV57 = 0 will turn off BEMF or speed stabilization Digitrax calls it.
http://www.digitrax.com/tsd/KB540/how-do-i-turn-off-speed-stabilization-back-emf/
It seems that Digitrax has revamped their tech support section of their web site for the better. Getting info earlier was a challenge.
The BEMF issue may not be the problem you are having but is the most common problem besides dirty track and wheels or not enough feeders from the track buss. If turning off BEMF does not solve the problem then there are other things you can check.
As noted, try deleting the consists stored in the Zephyr and then set the consist with the two engines. However, don't couple them together, keep them a couple feet apart. If they run fine like that, it could well be the BEMF issue. If the one still slows down, it's probably some other issue.
Not sure about Digitrax, but I know some decoders have an option where pressing a certain function button turns on something called "switching mode" where the engine's speed curve is cut in half. Maybe there's something in the settings on the one decoder that when it's in a consist, it switches into "switching mode"??
When programming a decoder, it's easy to get a number wrong and change a CV you didn't intend to. So, if turning off BEMF doesn't work, I'd maybe try doing a factory reset on both, then try running them at the same time using ID 003 for both. If that works, add their normal ID numbers and m.u. them together in a consist and see what happens.
If you are using "advanced consists" try setting CV57 to 102. This was recommended by Digitrax when I was trying to MU some locomotives.
WS
I was going to post about that before everyone went off on the same old wild goose chase as always, but too late I see.
The BEMF CV on Digitrax decoders that have BEMF - that wierd number where you have to set the second hex digit ONLY applies to CV19 consisting, which the Zephyr does not do by default. I use other decoders, TCS for non-sound, and they have BEMF and I NEVER turn it off in consist - I've never seen the need. I don;t see my locos 'fight' when consisted, at all. Even oddball ones with two TCS motor decoders and another loco with a QSI sound decoder, with BEMF turned on.
Also, BEMF will not make the loco stop. If it is stopping, odds are fairly high that the same address is selected more than once, perhaps during the consisting process. It's eaiser with a DT40x throttle, but from the Zephyr you need to select the loco that will be the top, make sure it is running in the desired physica direction (NOT the direction switch, the actual direction the loco moves. Make sure it is stopped and the direction switch is in Brake, then select the second loco and make sure it is running in the proper physical direction. Again be sure to stop it and sett he brake to stop. Now, select the address you want to be the consist address - this does NOT have th be the address of the lead loco. Then press the MU button. Enter the address of the first loco, and press +. Press the MU button and enter the address of the second loco and press +. Repeat for all locos in the consist. After you add each loco, the display will revert back to the TOP address, which is the one you will use to control the consist. If there are no more to add, pick a direction and throttle up.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.