There is a threaded hole on the front of the (tpi) intake base. The hole I'm talking about is below and (I think) to the pass side of the intake manifold coolant outlet (the part you would connect to the heater diverter valve when bypassing the TB).

My unknown hole looked like it opens directly to the coolant passage in the base so I was wondering if maybe a sensor goes there. What goes in this hole?

Next question: Do you know where I put the part?

 

its where the earlier cars have the cold start injector switch.

 

Thats where the CTS (coolent temp sensor) is on my car.

 

If it goes into the water jacket is must be the coolant sensor. It is on my car.

 

And it would be what on my 91 car? I can't find a post in which you list your sig, Drew, to see what year you have. I can see that you have an 87, Dustin, and you have an 86, 86. When did they stop using cold start injectors (i.e. do either of you have one) and what goes in that hole on my car that does not use a cold start injector.

 

You should have a couple holes in the front of the intake manifold, the only one thats used on your car would be the coolant temp sensor that runs to the ECM, there will also be another tap right next to it that was used on earlier cars for the sensor for the cold start injector.

If you have a CTS and another hole, the other hole is for the cold start injector which your car wouldn't have, hence why it would be an empty hole. Also it shouldn't go all the way thru.

 

*Edit* read the question wrong