[mark houghton]

Originally Posted by billjam

If you are trying to track plumbing on an emissions-equipped 930, this diagram might help.
It comes from the back of the 930 Owner's Manual if I recall.

Yep, I've got that and it is helpful. Specifically what I'm trying to decipher is electrical, the power/signal source for solenoid valves 37...one for startup vacuum retard blocking and the other sends a vacuum signal to air switching valve 33 for the air injection operation.
Terminal 7 on the fuel enrichment control unit (under the drivers seat?) seems to be the power source for both solenoids...but what tells them when to activate? The shop manual says the "thermo time valve" (to the dizzy) is closed at cold start to block retard and thus provide 15°advance, and opens back up in 20 seconds. Must be some sort of bimetalic strip inside the solenoid that heats up and and opens the circuit.