Hi Marco, Andreas, Guido & everybody else,
Found your forum at Pelican Parts BBS. I wish I knew German so I could read the posts.
On my Wife's 1982 924 turbo, the Seimens DIC contol unit under the dash went bad. The Porsche dealer told me the part is no longer available in the USA.
This unit reads the flywheel pickup sensor, intake air temperature, and boost, to signal the unit on the fenderwell time to fire the coil.
I replaced the distributor with an older one and added an MSD cd box to get the car to run. But, I wonder is the Seimens unit available in Germany?