Dash Pot (Dp) System - Toyota 4-Runner 1985 Repair Manual

EC-28
EMISSION CONTROL SYSTEMS (CARB.) - Dash Pot (DP) System
DASH POT (DP) SYSTEM
(AfT Vehicles Only)
A03046
Normal Driving Deceleration
DP Diaphragm DP Diaphragm
ECl187
EC1188 ECl189
To reduce HC and CO emissions, when decelerating the dash pot opens the throttle valve slightly more than at idle.
This causes the air-fuel mixture to burn completely.
Condition DP Diaphragm
Throttle Valve
Idling
Pushed in by return force of throttle valve Idle speed position
Normal driving
Pushed out by diaphragm spring High speed position
Deceleration Pushed in by return force of throttle valve
Slightly opens and then slowly closes to idle
position