How to solve a Rubik's cube 4х4 - Step 8
In the beginning of this step You should have 2 solved layers and one upper cross.
In the end of this step corner pieces of the up face should be in their places but they can be turned wrong.
To change the corner pieces of the up face, carry out one of the algorithms of 6th step for the Rubic's cube 3x3:
If You met the situation when 2 corner pieces are in their places and other 2 are not (these can be pieces one the same side as well as pieces placed diagonally from each other), carry out the following algorithm:
After this, use 2 first algorithms of this step to place corner pieces in their places.