Civic Si

Dashpot diaphragm chamber "A" slows the closing of the throttle valve during gear changes or deceleration. When throttle valve begins to close suddenly, its movement is slowed by the force of the spring in dashpot chamber "A" and the gradual increase of vacuum in dashpot chamber "B". A gradual increase in vacuum is caused by the restricted orifice in the manifold vacuum signal line.

Dashpot diaphragm chamber "B" is employed to increase airflow rate for fast idling at extremely low ambient temperatures. When dashpot control solenoid is activated by ECU during low ambient temperatures, manifold vacuum is not applied to dashpot diaphragm "B". This causes throttle to remain slightly open because throttle valve closing position is limited by throttle control rod.