Emission: Dash Pot (DP) System (M/T Only): Overview

To reduce HC and CO emissions when decelerating, the dash pot opens the throttle valve slightly more than it is at idle. This causes the air-fuel mixture to burn completely.

See Fig 1 for a dash pot overview illustration.
See Fig 2 for an operational illustration.

DASH POT OPERATIONAL TRUTH

Condition	Diaphragm	VTV	Throttle Valve
Idling	Pushed in by return force of throttle valve	Closed	Idle speed position
Normal Driving	Pushed out by diaphragm spring	Open	Idle speed position
Deceleration	Pushed in by return force of throttle valve	Closed	Slightly opens and then slowly closes to idle position

Fig 1: Overview Of Dash Pot System

Fig 2: Operation Of Dash Pot Under Different Circumstances