mysterious plug...

I just put my ZC in my 89 Si hatch and have one question. I took the wire harness from the si and wired it up for ZC no preblem but when I was hooking it up, theres this one extra plug underneath the intake manifold. it went to this canister type thing on the Si but theres nowhere for it to go on the zc. Anyone had this problem before and what did you do about it?

Hmm....I had a DX put in my HF and there's a plug just sitting there also, but I don't know where it came from so this post is pretty pointless I guess..:icon16:

so it runs?