System Operation; Purge Flow Control; Orvr (On-Board Refueling Vapor Recovery) - Toyota 2006 PRIUS Manual

System Operation

1) Purge Flow Control

When the engine has satisfied the predetermined conditions (closed loop, engine coolant temperature
above 74_C (165_F), etc.), the stored vapor gas are purged from the canister whenever the purge VSV
is opened by the ECM.
The ECM will change the duty ratio cycle of the purge VSV, thus controlling purge flow volume. Purge
flow volume is determined by intake manifold pressure and the duty ratio cycle of the purge VSV.
Atmospheric pressure is allowed into the canister to ensure that purge flow is constantly maintained
whenever purge vacuum is applied to the canister.
To Intake Manifold
Atmosphere

2) ORVR (On-board Refueling Vapor Recovery)

When the internal pressure of the fuel tank increases during refueling, the vapor gas enters the canister.
Because the vent valve is always open (even when the engine is stopped) when the system is in a mode
other than the monitoring mode, the air that has been cleaned through the canister is discharged outside
the vehicle via the fresh air line. If the vehicle is refueled during the monitoring mode, the ECM will
recognize the refueling by way of the canister pressure sensor, which detects the sudden pressure increase
in the fuel tank, and will open the vent valve.
NEW FEATURES - 1NZ-FXE ENGINE
Purge VSV (Open)
ECM
Canister Pump Module
Vent
Valve
(OFF)
Purge VSV (Close)
ECM
Vent
Valve
(OFF)
VSV (For Purge Flow Switching Valve)
(OFF)
VSV (For Purge Flow Switching Valve)
(OFF)
21
NF
01REG03Y
01REG04Y