Let p be a prime number, T a class of finite groups closed under extensions, subgroups and quotients, and suppose that the cyclic group of order p is in T. We find some sufficient and necessary conditions for the pro- T completion of an abstract orientable Poincare duality group G of dimension 4 and Euler characteristic 0 to be a profinite orientable Poincare duality group of dimension 4 at the prime p with Euler p-characteristic 0. In particular we show that the pro- p completion (G) over cap (p) of G is an orientable Poincare duality pro- p group of dimension 4 and Euler characteristic 0 if and only if G is p-good.33401421