Motors running rough


I’m having a strange thing happen. I did a flight and found the performance not that great. Landed due to the battery running low. Changed to a new pack, then found the motors running really rough at idle and the motors not wanting to spin up. Sounded like rusted nails in a tin can.

My system did report software updates and I upgraded both Mission Planner as well as Copter to the latest versions.

The same issue persisted so recalibrated everything including the ESCs. Problem persists.

If I rotate the motors by hand then there are no obstructions.
if I test the motors one at a time motor 1 runs ruff consistently. Motors 2,3,4 runs smoothly every time.

Arming the system and getting initial idle speed, all the motors run rough.

Logfile of a short bench test at


MOT_SPIN_MIN is lower than MOT_SPIN ARM. You don’t want that. You have a reason for MOT_THST_EXPO at 0.2? Is this log with no props I suppose? It would be more useful to see the log from it flying.

Thanks for the response. Not sure where the MOT_SPIN_MIN and MOT_SPIN ARM values came from. I reset them to their defaults (0.15 and 0.10 respectively.

The motors do not spin up fast enough to get the drone in the air, even at 100% forward stick.

I did another motor test with motors 2, 3 and 4 running smooth but 1 sounds like its timing is out.

I’ll try run some more tests a bit later.

How to set MOT_SPIN_MIN and _ARM

Thanks Alisteri set the values as they should be and still had strange behaviour

I defaulted the FC and reran the entire setup process, fligt settings, radio calibration, esc calibration, etc. The immediate motor test had all four motors run smoothley and i took the drone for a flight. All seemed fine in stabalise mode, tried alt hold and position hold. In position hold the drone drifted a bit and the controlls become progressivley worce.

I reset the the FC and set to stabalise. Spun the motors up a little and they sounded like a car misfiring, smooth cough, cough, smooth. I could not take off in this state.

Ive uploaded two log files. One testing stabalise, alt and position hold, the other of the irratic motor behaviour.

This is very odd.

I try to run auto tune while I was in position hold but this had no effect on the drone. it did not seem to do anything so I disabled it again.