Ok, when I bought this car from a friend he had wired in the IACV, and did it very half-assed.

The car is a manual transmission, and is currently using a 3-wire IACV and plug, stock Y7 manifold.

The yellow/black wire was wired in using the wire from the stock harness. Then, he had two wires connecting the orange and the black/blue wires from the plug, to pins 13 and 14 on connector "A" of the ECU. It was done very sloppy and when pushing the car hard (track days) the check engine light would come on for the IAC and it would idle like crap.

So, this car may have had a B18 in it before I ever took possession, and the wiring may be a bit weird.

The black/blue wire was in position 12 on the ECU connector, so I pulled it out and moved it back to position 14. I put a new pin into 13 and connected the orange wire that was just hanging out in the footwell. Wired everything back up in the engine bay to the stock harness, connected the battery and keyed on, and the car is throwing a check engine light now. Anyone think I did anything wrong here?

 

My observations are according to this photo:

 

Nevermind.

I had the IAT sensor unplugged. We're good now.

Move along. Nothing to see here.... :D