umm.....kinda new to rotaries and want to know what this part is called and what it does...

 

Haynes declares it as part of the throttle and dynamic chamber.... i'll keep looking some more though

 

I believe its part of the thermowax assembly, Not exactly sure what that part does, though.

 

And now for the right answer...

Those are the part of the double-throttle system, the thermovalve on the rear and the vacuum actuator on the front. Note that the the thermovalve is mounted on the thermowax. They share the same coolant flow but they are not the same thing.

In the TB the secondary bores have two throttles each. The downsteam ones are controlled sequentially with the primary throttle by the accelerator pedal. The upsteam throttles are controlled by the vacuum actuator. They are sprung open, but when the engine is cold the thermovalve allows manifold vacuum to reach the actuator, which pulls them closed. The vacuum is held in the actuator by a check valve. This happens as soon as the engine starts, and is there to prevent bad drivers romping on a cold engine. When the coolant flowing through the thermovalve warms up to ~140degF, the vacuum is released and the upstream throttles spring open and stay that way until the next cold start.

On Turbos the system works the same except that once the engine's warm the upstream throttles work in tandem with the primary throttle, but their opening speed is damped to prevent a stumble when the throttles are opened too quickly.

 

It's a vacuum switch that's controlled by water temp.
It controls the second set of butterfly plates. The "choke".

 

I never new how that system worked exactly, good to know. The double throttle system was never operating in my car, the P/O just tied the upstream plates open.

 

It's not a "choke". That's completely different, and only applies to carbs.

 

I know fuel injection does need a choke. It's not literally a choke but, it does the same thing. It blocks of the second set of throttle plates when the motor is cold.
Allowing air in once the motor is warmed up or when a needed. Sounds like a choke to me.

 

The function of a choke in a carb is completely different. It enriches the mixture by speeding up the air through the venturi so the engine will idle smooth when cold. The double-throttle sytem does nothing even close to that. It has nothing to do with mixtures or idle quality; it's purely an "idiot-proofing" device. Japanese FC's didn't even have it.

 

im guessing your wondering what it is so you can buy a new one cause it looks like you snaped the one plastic nipple off...i did the same thing.....just call mazda and tell them you need a new water thermo valve for the throttle body i think its around 50$