I'm taking my ex wife back to court for placement of my 16 year old son are my chances good for winning. He wants to live here. No drugs, abuse here

Assuming you are past the 2 year “cooling off” period from your initial custody orders, you will need to overcome the presumption that custody should remain “as is” by providing compelling and substantial reasons why placement should be changed. The fact that your 16 year old wants to come and live with you, if the other parent objects, is not going to be enough in my opinion, to sustain a motion for modification of placement. The wishes of the child is a factor, among many factors, that the court will need  to consider on your motion to have the child come and live with you.