what is the valve on top of the intake manifold for?



i put the b18b1 from a 96 rs integra in my 95 civic...i am using my stock cars harness so i don't have a plug for it in my harness...should i just block off the nipple coming from it which i'm guessing is vacuum...it's an obd2 intake manifold in an obd1 car...guessing the ecu won't look for whatever sensor it is so leaving it unplugged shouldn't throw a CEL