how do i fix my kangoo running problem?

my kangoo van had developed a realy bad diesel knock then would smoke and be under power, while driving if you switched the ignition off and back on it would run perfect for about 5 seconds then start the horrible noise again! i was told it would be the timing advance/retard solenoid but when put on a diognostic machine it wouldnt connect to the ecu. the fitter said there would be a live missing powering the ecu and there should be four lives?? its puzzeld a lot of mechanics they all said you shouldnt have bought a renault lol! can any one help