I had a bad crash a few months back. A motor ripped off my 180. Screws came loose while in air. Boom!
So I did a rebuild, with the same ESC and a new motor. I put the quad out on my back porch and all four motors were doing something weird. The motors had this stutter type motion and got really hot. The quad wouldn't take off. I took the quad back to my bench and fired up the quad without props. The motor I had just replaced started smoking and pretty much bit the dust. So now I've replaced the motor again and replaced the ESC in question.
So here is where I'm currently at in the process:
After replacing both the motor and esc, I put the quad on the bench with only one motor / prop attached at a time. I give the quad throttle and it seems to act normally. Only one motor out of the 4 has what I'd call a vibration or pulsating noise at a specific throttle amount. The other three seem to act completely normal. Then when I attach all 4 motors again and go back to the porch for outside testing, the weird stuttering comes back.
My setup includes the M4, Joerg Expander board, KISS 12A ESCs, Quatos, on a 180mm quad with DYS1306 3100kV motors. I have a video that I'll link to that exhibits the issue. I have my config.txt as well. Logs will come this evening.
Things to try - different M4, new ESCs, new motors?, different Joerg expander board?
Here are some dropbox links...
.Mov
https://www.dropbox.com/s/lp58pyv49c1fa ... 1.mov?dl=0
Config
https://www.dropbox.com/s/zpml2io6xbfkd ... 9.txt?dl=0