Hi fan community! A case for specialists: I have a Golf IV variant with 100 hp TDI. New is: Turbocharger, air mass meter. Compression has been checked recently, perfect, almost identical. Problem: The engine has good and bad times. In the bad times it suffers from severe power loss, the turbocharger uses partly very late. Here can happen: Suddenly the gas train is gone, the engine switches to emergency running program (then hardly more than 90). The workshop is sure that it is located on the air mass meter. However, an exchange of this did not change. Problem continues to occur. It is also a kind of ringing that is getting louder and louder. The workshop says that it is a completely normal intake noise. However, it sounds more than a ringing, have also confirmed to me acquaintances. What now? Who can help me?