Did you connect both green wires to switched power?
Did you run a dedicated black wire direct from the coil to the tach?
Do not use any black wires in the Motronic engine harness to the tach.
you should fuse the fuel pump wire [green violet 15 amps] and fuse the green wires- one is switched power for turning on the ECU and the other one is switched power to the coil.
Don
Is this still the case? In this thread: http://www.e9coupe.com/forum/threads/e34-3-5-direct-drop-in.21463/page-2
It seems to infer you WOULD use the little black wire from the chassis to the 1.3 engine harness???