  We study the effect of mixing two rules on the dynamics of one-dimensional
cellular automata by large scale numerical simulations. We calculate the decay
of the magnetization for the Domany-Kinzel automaton (XOR/AND mixing) to its
equilibrium value in the three phases. This requires system sizes in excess of
1 million sites. We also find severe finite size effects near the new critical
points recently proposed on the basis of transfer matrix arguments.
