the threded hole in the water pump is that for a sensor? can i just plug it if the pump is not going into the ori car the motor came out of? or is it for somthing important?

 

That hole is for the coolant temp sensor. If you don't need it, you should just be able to plug it with a brass fitting or something. Just make sure you put some teflon tape on the threads to prevent leaking.

 

It's the hole that the ECT (engine coolant temp) sensor plugs into. The PCM needs that sensor to make A/F ratio determinations and know when to kick the cooling fans on. Unless you're planning on ditching your EFI and converting to a carb setup, it's best to just leave it alone.