I have a 04 mini cooper s. We bought the car for a project car and we are having a hard time getting the timing right. We lined up the arrow with the dots on the timing chain. But everytime we go to start the car it is throwing the timing off by 5 or 6 teeth. We took it apart a third time and turned the cam shaft by hand after timing the chain again. And once again it was off by 5 or 6 teeth. What could this be ?