single wire ignition bypass connector?

WHAT IS THE FUNCTION OF THE SINGLE WIRE IGNITION BYPASS? WHAT IS ITS PURPOSE? I replaced the intake manifold on my '89 350 tbi truck today. I updated to an edelbrock performer. while I was double checking all of my connections I found a male spade connector in the harness behind the distributor plugs. The haynes manual makes a picture reference to it as the ignition bypass connector but never states its function. There is a separate single wire that is disconnected when setting the timing. Does anyone know the function of this connection? There is also a bank of vacuum connections on the right side of the engine. There EGR and the MAP both connect here, there is an open port- is this to keep a reference to atmospheric psi or am I missing something? All seems to be in place but I want to make sure before I fire it up in the morning. Thanks for any input I know it isn't much info........
Chris

Look around, there's another hose lurking there somewhere.

I have double checked and driven myself nutz........all of the tbi ports are accounted for, as well as the EGR and MAP sensor. I don't recall pulling anything off here but it is bothering me that the vac. port is open. Should I cap it off?

I found a diagram that says it is a vent(to atmosphere for bar changes?)
http://www.autozone.com/az/cds/en_us...rInfoPages.htm

I would still like to find out the function of the bypass connector. It is not the EST wire that retards timing due to the knock sensor!