Motors cannot run maximum speed all at the same time

Hello everyone… I’m working on quadcopter. Everything is fine. Except that when I move the throttle stick up to increase the throttle to make the drone take off only one motor keeps moving at full speed while other motors are not moving at all. In the beginning when throttle is low, all motors move together, but when the throttle value increases, only one motors keeps rotating. The one motor that keeps rotating is not necessarily the same one. For example, let’s say that we have A, B, C & D motors. At high throttle, sometimes, motor A keeps rotating, however, at other times, let’s say motor C keeps rotating, and so on. RC transmitter settings are fine.

Do I need a power distribution board? if I do, what type of PDB do you recommend? I have four 20 A ESC’s

thank you very much in advance!

Can you provide some more details, what flight controller are you using? Have you done an ESC calibration, are you taking off from a level surface?

I’m using apm 2.6… Yes, I have done ESC calibration… Of course I’m taking off from a level surface… Sorry, It didn’t come to my mind to mention these details

My suggestion is to manually test the motors within mission planner (remove your props first) then you can make sure it is working fine as you can directly control the motors here… If that works, then it might just be a balance issue of your quad when taking of as one motor is working harder to keep the quad level. You can do a test at low altitude hover to make sure as if you crash below 1m then there is a low chance of any damage.