I am having this problem when building my quadcopter. Three motors don't spin until throttle reaches 16% of full throttle. Only one of them is working fine. But once they are all spinning, it seems they are at the same speed.
The motors I use are Turnigy D2836/8 1100kv. The esc are Turnigy Multistar 30A Slim V2 ESC. I am using a 3s lipo battery and a arduino mega adk to control the motors.
It is very weird and I didn't see similar problems posted. Do you guys know how I can fix it?