Set steps per unit in Mach3 for Stepcraft 420

Confused and frustrated

Stepcraft 420 with mach3

I read on here that ideal steps per Unit in motor tuning is 133.333333.

I tested this on a 8cm square profile job. Result: x-axis= 8 cm, but the y-axis=8.7.

I went then to the section settings where there are steps per unit set button to help you test how each axis moves per unit.
x and z are okay, but moving y double than its command.
Mach 3 suggests automatically adjust it and we have the half of steps per unit for the y-axis, so 66.6.

I then tested and found my square with x = 8, y = 4.4

What happens?