I found a loss of performance at my b4 tdi. therefore I asked a test center (verkehrsclub in österreich) for a compression test. The statement was that they tested electronically (electrically), i.e. with a tongue-ampermeter. my question: does this measurement process do something, it is clear to me that one cannot determine exactly which cylinder has a loss of performance, but in principle it would be enough for me if I knew if there was a leak at all. The test would be free of charge. I could only have a more detailed test done in a workshop that is of course more complex and expensive. what do you say?? mfg