Description & Operation
This system prevents throttle valve from suddenly closing, thus reducing CO and HC emissions. While idling, throttle valve is in idle speed position and Throttle Positioner (TP) diaphragm is pushed inward by return force of throttle valve. During normal driving, throttle valve is in open position and TP diaphragm is pushed outward by diaphragm spring.
During deceleration, throttle valve opens slightly and then slowly closes to idle position, while the TP diaphragm is pushed in by return force of throttle valve. At this point, the function of the air valve provided inside the dashpot diaphragm prevents throttle valve from being closed suddenly.