Engine chugging when sitting still

I'd suspect an issue with the smoke unit, perhaps the motor is going.  If the smoke unit is changing the audio, it sounds like it's screwing up the board operation.  You might be loading down the 5V output.

Thanks John,

The smoke unit does sound like it needs oil which is probably causing it to draw more current. I'll oil it first and if that don't help I'll change the unit. I also would like to know if the wick needs to be touching the heating element or is there supposed to be a small gap ?

You just have to change the fan motor as a rule, it's the part that would likely cause an issue like this.  When you put the new motor in, make sure it runs in the correct direction, CW looking down from the top.

What model number is this?  Yes wick should be touching (pinched between both elements).

The is a 10K resistor that is suppose to be in the tach return line to prevent inadvertent chuff.  This may be a very early model.

Or a pinched or frayed wire is causing feed back.   G

Model #30-1280-1. The smoke unit in this is a little different then others I have worked on. The motor has a good gap between itself and the fan housing, making it very easy to oil the motor bushing. Others, I had to take apart and pull the fan off the shaft. I don't see a resistor, unless its in the tender.

Yes some smoke units have that gap.  Is this a PS-2 5V with the board in the engine?  If so adding a 10K resistor in line with the orange wire from the tach to the 7 pin connector should stop any chuff in neutral.

If that doesn't work then John is correct and a "going" bad smoke unit can cause issues.  I have not see chuff in neutral but I have seen it cause erratic operation, no speed control, bell or whistle signals or flat out shutting down the board.   G

Yes, it is the 5 volt board and there is no resistor, so I'll add one. Oiling the smoke unit motor did quiet it down but still chugs. I do also notice while moving it around on my test track, an awful lot of pick up roller sparking, even the drive wheels, but not as much. Cleaned the tracks good but its still doing it.

Are you sure it isn't just the sound file of the air pump. Is it a chunk-chunk sound every few seconds?

Sounds like it's drawing excessive current, did you try measuring the power draw to the track?

Yes, Its definitely chugging. I'll check the current draw and see what it is.

That's what came to my mind: compound air pump sounds?

Current draw sitting is .83, moving 1.07. Voltage 19.4.

Noticed the pick up rollers axles were dry, so I oiled them up good with regular MTH oil. It totally eliminated the sparking (shows the importance of regular maintenance). The oil must help with continuity. I will work on installing the resistor and give the forum a follow up. Thanks everyone for your help.

I think I can

I think I can.............

Sorry it took so long to follow up with this post, but I had to order the 10K resistors that GGG suggested to try to get rid of my chuffing in neutral. I added the resistor to the orange tack wire and it did eliminate the chuf problem, but when I advanced the throttle, it took off at full speed. Could 10K be too much resistance?

I hope you tried a feature reset first? Menu/Advanced/reset engine/ feature reset.

Thanks Gregg. Never tried the feature reset. Did you mean before or after adding the resistor?

I'd try it before.

Ok. I will remove the resistor and give feature reset a try.

It's alive! Run for your life.

I removed the resistor and did both a feature reset and a factory reset, but it didn't help. The resistor did stop the chuffing when the smoke unit was turned on like GGG said it would, but I believe he may have given me the wrong value. It was blocking the tack signal and allowing the motor to run at full speed. Hopefully he will respond when he sees this post is active again. I also tried a new smoke unit, but it still did the same thing. The sound is not the compressor.

Good news. Tried a 100 Ohm resistor and it did the trick. Running like new. Thanks everyone for helping me solve this problem.

DAve it should be 10K.  It may be on the board if it was moded.  Since the 100 works your good.  The alternative would be a possible bad tach reader and you can change it and remove the 100 ohm resistor.  If it works, the tach reader was the issue.  If not and the 100 ohm resistor is needed, the board may be going south.  G

Thanks for your reply G, I'll run it hard for a while and see how it holds up. May the Gods of the railroad be with it.