i took out the flywheel and changed the trigger teeth to massiv steel ones. Then I changed the position of the missing tooth. I really was at approximatly 15-20 degrees ATDC. I guess that was the main reason why the ECU did not see the gap. It always measures the time difference to the previous tooth. According to the gap tooth factor it determines the missing tooth. Since the RPM because of the compression shortly before TDC is a lot lower than directly after the TDC, the time difference between the two regular teeth in the lower RPM sector shortly before TDC and the difference at the missing tooth while accelerating after TDC does not reach the minimum factor 1,35 to find the missing tooth... understandable?
Well, know the missing tooth is at 90degrees BTDC and is perfectly recognized. The ECU show RPM and the engine runs great. Thanks everybody for the hints and advises!
Toni