My Ford puma 2001 1.7 zetec is only running on two cylinders. No 2&3 are running and 1&4 are not. I've replaced the plugs and coil pack, im pretty sure the leads are ok. Before forking out more money on leads just to be sure, does anyone know where the cam sensor is, incase its dirty and sending a faulty signal? Does anyone have any other suggestions on the cause? Thanks.