Sinc esc/motor

There is something that I do not understand. I have synchronized the esc/motores, so much with the procedure in group as individual. The case is that on having finished this synchronization, it looks like all they begin in the same point of the accelerator. But when I am going to prove the royal raise, I see that there are two engines that always receive less power have even they start late, much more above in the accelerator. Other one proves that I did, is to start the engines individually from the recipient (without the arducopter of for way) and surprise goes, there if that are OK. It is as if when I have the arducopter happening between them, the engines were not receiving uniformly the signs or the power.