so this has been driving me nuts for the past two weeks. running a 5inch freestyle build, emax eco2 2306 motors on 35a blheli_s ESCs, and one of the rear motors just randomly twitches. not like a full desync, more like a small stutter that you can feel in the sticks and see in the blackbox data as a brief spike on motor 3 output.

ive already swapped the prop on that motor thinking it was a balance issue, nothing. resoldered the motor leads because one joint looked a bit cold, still doing it. the weird thing is it only seems to happen after a few minutes of flying, not on the bench when i spin it up. makes me think its thermal related maybe? or ESC signal issue under load?

anyone dealt with something similar, genuinely dont know if i should just replace the motor or start suspecting the ESC at this point

had almost the exact same thing on a build last year. turned out to be a partial short in the motor windings ? one of the stator wires had a tiny nick in the enamel coating from where id routed it too close to a standoff. totally fine on the bench because current draw is low but under real load it would start acting up after the motor warmed up and the resistance changed. you can sometimes catch it with a multimeter checking resistance across each winding pair, if one reads noticeably different from the others thats your culprit. swapping the motor fixed it completely for me.

could also just be a dying ESC honestly. blheli_s 35a units arent exactly known for longevity especially if youve had any hard crashes. i had one that would throw random twitches only in certain throttle ranges, ended up being a mosfet that was on its way out. reflashing the firmware sometimes masks it for a while but it always comes back. if you have a spare ESC lying around id just swap it and see what happens before spending more time diagnosing