I adapted a turbo2 fc intake to fit on my old school 4 port and am EFI converting it. As far as I understand it, FDs actually close the peripheral intake runners when the secondary injectors are off. Does the FC have something similar? Is it just the second set of butterflys in the Throttle body? Or does it always pull air into the peripheral ports even with no fuel? If it does close in some fashion, how does the ecu know when they are closed?
sorry to dump so many questions in one thread, but I cant seem to wrap my head around it.

 

peripheral? the FC and FD (and GSL-SE) use a staged throttle body, its like a mechanical secondary carb without the float bowl
so at small throttle openings its just running from the primary ports, and as you open it, the secondary's open

 

so the secondarys are controled by the throttle body. I think mine must be modified, because all three butterfly's open at the same time. There is a second set of butterfly's in the peripheral ports, are those supposed to open at a certain Throttle percentage? Is there just a known percentage of Throttle when secondary opens up and that fixed value is how the ecu determines when to fire the secondary injectors?

 

I looked at it for a bit, and it must just be the tune. The primary only opens like 5 degrees before the secondarys open. I guess my main question is, does lean air collide with rich air from the primary in the housing? Or is the tune supposed to make sure the secondary gets some fuel so it's not saturated in the primarys and super lean in the secondary runners?