okay this has been driving me insane for like two weeks. crashed my 4inch, fried motor 2, replaced it with what should be a compatible unit (same kv, similar stator size, different brand). everything looked fine on the bench, motors all spin, passed the motor direction check, went out to fly and the thing keeps cutting out on that corner specifically. not a full crash, just like it desynchs or something and the quad flips.

ive tried lowering the RPM filter, rerunning motor direction, even swapped the ESC signal wire to a different pad thinking maybe i had a cold solder joint. still does it. battery is fine, voltage looks normal on OSD. im running a 4in1 ESC which i guess complicates things because i cant just swap that one corner independently.

is it possible the replacement motor is just drawing too much current for some reason and browning out that ESC phase? or am i missing something obvious here. been flying for about 3 years so im not totally new to this but this one has me stumped

what brand is the replacement motor? some cheaper motors have way worse winding consistency and can cause all sorts of desynch issues especially on a 4in1 where the phases are all sharing a common ground path. ive seen this exact thing happen with motors that technically spec the same but have higher resistance windings ? the ESC firmware gets confused during rapid throttle changes. try running motor 2 at like 80% max throttle in the motor tab and see if it gets noticeably hotter than the others after a minute or two.

had something similar a while back and it turned out one of the motor wires had a strand or two broken inside the insulation from the crash, not the new motor but one of the phase wires connecting to the ESC pad. looked totally fine visually. only found it when i wiggled the wire and the motor stuttered. worth checking all three pads on that motor real carefully, not just the solder joints but the wire itself close to where it meets the connector or the ESC pad