when i rebuilt my S1 we spent 3 days trying to find the cause of no spark. relpaced everything with no luck.

turned out it was a small green wire!!

There is a green wire which runs from the coil to the fuse box. It runs round the headlights and rad and back up to the box, coming in and out of the loom.

It may be worth checking this and bridging it to see if its the cause, as the wire is part of the circuit responsible for the 'hall effect' distribution.

I was lucky in the respect that my mate is a ford technitian, so we managed to borrow a "break out box" (an early diagnostics tool) which drew us to the green wire.