Up until a few months ago I was happily solving my 4x4x4 cube, then, thanks to a medical thing, I've lost/forgotten a few algorithms. I've got all of them back except 1, rotating the last 3 edges.
edit: this isn't a parity issue, it's the same as the 3x3x3 case (sorry I wasn't clear)
What I remember is this:
- Everything is oriented correctly and the corners are positioned correctly.
- The cube is oriented so the correctly positioned edge is facing front and the last layer is on top.
- I never rotate the back face.
I've found a quite a few algorithms that can solve it, but not for those criteria. I've not found one that has the correct edge facing front, and when I rotate the algorithm I'll need to rotate the back face.