Hi all.

I have an 87 iroc 305 4bbl and am struggling to untangle the vaccum line spaghetti. Trying to keep it all original. I think I have it mostly solved except for two issues:

There is a sensor on the pass side mounted on the firewall just above the transmission stick tower. It looks like a map sensor. It has a vaccum port but there is no sign of a hose or open connection. Anyone know what / where it supposed to connect to or if it's just open?

Secondly, the ported vaccum switch on the thermostat housing has two lines. #1 goes to the carb. #2 goes down around the intake and stops at the rear. Again - no sign of an open connection or a mate. It doesn't reach the map sensor looking thing. Is it supposed to be open or what does it connect to?

Anyone have one of these that hasn't been Frankensteined?

 

The other sensor that looks like a MAP sensor is the baro sensor... it measures the pressure of the atmosphere, i.e. the engine's vacuum (indicator of load is the difference between the 2) It gets no vacuum line.

Vacuum sw on the water outlet is for the EFE valve (valve in the exhaust between pass side exh man and Y-pipe).

 

Thanks! I think its all straightened out. The efe valve is long gone in this one though. Ive never fully understood their purpose. Is it important?

 

Hard to imagine how it could be "gone".

Where you live, it's probably worthwhile, at the least.