last week my car refused to start so i locked the car and opened it a few times and it started. at the weekend it would only turn over and not fire. Today the AA came got it to start but when i held the throttle slightly in at the same position the revs rised and fell and it backfired each time. Believe it may be a cam shaft sensor as i could here the fuel pump relay cutting in and out which was causing the car to rev and backfire. Car is now at an auto electrician who is going to vag com the car see what the crack is and hopefully fix it. anybody else had similar problems??