I am replacing the stock motor in a 90 Si with a SOHC ZC. I ordered the motor from hmotorsonline. The motor I bought is an OBD1, the guy there said that if I just switched the intake manifold and distributor everything else would be exactly the same. Everything seems to be the same except this plug. The stock motor has that two pronged plug and the ZC does not. Does anyone know what it is for and what I should do about it? Also if anyone knows of any other issue or thing I need to change or account for on this swap it would be greatly appreciated.


On a side note I bought this hatch from a guy who said "the motor just quit". I added pictures of the block and oil pan.

 

I left mine unpluged on my B16. I was told it wouldn't hurt anything with it being unpluged. Car runs fine.