White smoke when cold start?

I have a 1992 Iveco 75E14 4 cylinder horsebox, when starting from cold it has to turn over 6or7 times before it starts then only initially seems to run on 3 cylinders at best with white smoke coming out of the exhaust, after a few seconds it will start running on all 4 cylinders but white smoke continues until engine is warm, once warm the engine will start within 2 revolutions and no white smoke & running fine, I have had the injectors done, and the cylinder head refurbished, can any kind person help me with my quandry.