The car had been stood for a week in very cold weather. When i tried to start it it turned over but very slowly. Changed the battery with no improvement and checked for 5v sensor voltage so i think the ECU is ok.
After several attempts the engine backfires through the manifold, which actually blew the hosing apart.
i cant find anything relating to this so wondered if anyone had any ideas before i have to spend loads at the dealers.
cheers