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

EC-8 EMISSION CONTROL SYSTEMS (EFI) - Dash Pot (DP) System
DASH POT (OP) SYSTEM
(MIT Vehicles Only)
VTV Air Filter
EC1201
Normal Driving Deceleration
VTV VTV
EC1202 EC1203
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 VTV Throttle Valve
Idling
Pushed in by return force of throttle
CLOSED Idle speed position
valve
Normal driving Pushed out by diaphragm spring
OPEN High speed position
Deceleration
Pushed in by return force of throttle
CLOSED
Slightly opens and then slowly closes
valve
to idle position