The control pressure regulator acts like a “choke”, to enrichen the fuel mixture while the engine is warming up.
The auxiliary air regulator acts like a “fast idle cam” to slightly increase idle speed while the engine is warming up.
Control Pressure Regulator (engine cold)
When the engine is cold, the bi-metal strip in the control pressure regulator is also cold.
The control pressure regulator opens, thus reducing the control pressure on the top of the control plunger. This allows the air entering the engine to lift the sensor plate and control plunger higher.
When the control plunger is lifted higher, more fuel is delivered to the injectors and the fuel mixture is enriched.
Control Pressure Regulator (engine warm)
As soon as the engine is started, an electric heating element inside the control pressure regulator begins heating the bi-metal strip.
This causes the regulator to gradually close,thus raising the control pressure at the top of the control plunger. Now the air entering the engine cannot lift the sensor plate and control plunger as far.
This reduces the amount of fuel delivered to the injectors and leans
the fuel mixture as the engine warms.
Auxiliary Air Regulator
The auxiliary air regulator provides additional air for idling during warm up.
When the engine is cold, the gate valve is open and air can bypass the closed throttle valve.
After the engine is started, the electric heating coil warms the bi-metal strip which gradually closes the gate valve.