Ok, here goes.

EM-1 Si with b18a block, 1999 b16 head. In december i pulled off the tb and Intake manifold and some other stuff.

Yesterday I finally put on my new AEBS manifold and TB. Now that i have it all torqued down, and together, i noticed a plug below the TB thats unplugged, and i cant tell where it goes. (yeah sounds dumb)

Its a square plug, below the tb, (loose, its kinda sitting down near the Speed Sensor, but its not that!) It comes off the harness by the Intake manifold support bracket, there is 2 plugs, if i remember right the other is the tps plug. Does anyone know what this is? Not the map sensor, thats a round plug, and i cant think of what this goes too.

Could it be the plug to the knock sensor?? I dont remember what that looks like and i dont wanna have to pull the IM back off if its not necessary.

 

knock sensor would be on the block, and wouldnt require removal for the IM install (god, I hope not, anyway)

Could be the IACV plug.

 

knock sensor

 

Thanks guys, I figured it out though, it was for the damn primary 02 sensor!

I had the header off the car when i didnt see a plug, well I just had a blonde moment. oh well. All is well

 

Dang. I was way off.