I was not able to remove the bottom plate with the coolant inlets and air sensor ports from my old TB and transfer to new TB. so I installed it w/o this piece I bypassed the coolant lines. but I have this wicked vacuum leak sound. can you buy this part separately or do I need to get a TB off ebay with the whole assembly and start over.

 

That is the idle air control motor housing, you HAVE to put that on.

 

Yes, it is an absolute must have. Those screws have proven to be a PITA for many members. You can get new housing and screws from Hawks. The screws can also be obtained through Fastenal/McMaster/Atlantic Fastener/ Maybe even your local Hardware store.

There is a port to that hosing in the plenum. The IAC closes and opens this port to control your idle. I can't imagine you being able to get a healthy idle without it.

 

thank you , I also just found , TPIS INC for parts which sells the housing if you have done the coolant bypass for 74 buks. I could not get that housing off all 8 bolts snapped and bent my torx bit. lol i

 

I'll play Devil's advocate here... In theory at least, you could just bolt a blockoff plate to the bottom of the throttlebody to seal off the vacuum leak. You would have to adjust the throttle body stop to hold the throttle far enough open for the engine to idle. Without the IAC, cold starts would be more tricky, and you'd have to fart with it a bit to find a setting where it doesn't stall coming to a stop. Think of it like having a carb without a choke. Definitely not the preferred way to go, but it's certainly possible.

But yeah, either get the housing from another TB, or buy the TPIS piece.