What is right under the throttle body orfice? (Pictures included)

My throttle body is dirty as hell and whatever is under it is all clogged up! What is under the throttle body orfice and how can I unclog it?

Also could someone identify the sensor at the top also? It’s not the MAF sensor, that’s at the front of the throttle. This is the back of the throttle that connects to the Intake.

It looks like the idle air control valve port.


How would I clean it ?

Remove the IAC valve, and clean it and the throttle body with throttle body cleaner.



The clogged up passage at the bottom of the throttle body (right of picture) is a coolant passage. Check the intake manifolds’ corresponding coolant passages for clogging too. The item at the top side of the body (left of picture) is the IAC valve.


You have a throttle position sensor on the butterfly shaft. The bore of the TB needs to be cleaned. You open butterfly and clean it out. Yes the inlet is supposed to be clean but it has a small effect on performance.

Safe to use Carb cleaner on IAC valve?

GM recommends against using cleaners on the electronic components, but I’d think wiping with a rag dampened with some cleaner would be okay. Use a rag and throttle body cleaner on the body and throttle plate.