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Lexus ES300 (2002 year). Manual - part 131

ENGINE – 1MZ-FE ENGINE

EG-47

189EG31

ORVR (On-Board Refueling
Vapor Recovery) Valve

Vapor
Pressure
Sensor

Vacuum
Check
Valve

Tank Valve
Assembly

Tank Pressure
Valve

Charcoal Canister

Pressure
Switching
Valve

Air Inlet Valve

Air Valve
Assembly

Air Drain
Valve

VSV
(for Pressure
Switching Valve)

VSV
(for Canister
Closed Valve)

Purge Line

Flesh Air Line

Service
Port

Canister
Closed
Valve

From Air
Cleaner

VSV
(for EVAP)

To Intake
Manifold

Purge
Valve

12. Evaporative Emission Control System

General

The vacuum type has been adopted on the ’02 ES300 to detect leaks in the evaporative emission control
system. This vacuum type detects leaks by forcefully introducing the purge vacuum into the entire system
and monitoring the changes in the pressure. It consists of the following main components:

A VSV (for canister closed valve) that closes the fresh air line from the air cleaner to the charcoal canister

has been adopted.

A VSV (for pressure switching valve) that opens the evaporator line between the fuel tank and the char-

coal canister has been adopted.

Function to close the purge line from the air intake chamber to the charcoal canister for this system is

added to the original functions of VSV (for EVAP).

A vapor pressure sensor that measures the pressure in the fuel tank while checking for evaporative emis-

sion leaks and sends signals to the ECM has been adopted.

ENGINE – 1MZ-FE ENGINE

EG-48

208EG32

To Intake
Manifold

From Air
Cleaner

Open

208EG33

Open

To
Atmosphere

Operation

1) Purge Flow

When the engine has reached predetermined parameters (closed loop, engine coolant temp. above 74

(165

F), etc.), stored fuel vapors are purged from the charcoal canister whenever the purge valve is

opened by the ECM. At the appropriate time, the ECM will turn on the VSV (for EVAP).
The ECM will change the duty ratio cycle of the VSV (for EVAP) thus controlling purge flow volume.
Purge flow volume is determined by manifold pressure and the duty ratio cycle of the VSV (for EVAP).
Atmospheric pressure is allowed into the canister to ensure that purge flow is constantly maintained
whenever purge vacuum is applied to the canister.

2) ORVR (On-Board Refueling Vapor Recovery)

During refueling, low pressure above the diaphragm in the onboard recovery valve lifts allowing fuel
vapors into the charcoal canister. At the same time, the air drain valve opens and the charcoal absorbs
the fuel vapors.

ENGINE – 1MZ-FE ENGINE

EG-49

208EG34

189EG33

Open

From Air
Cleaner

To Intake
Manifold

Open

Canister
Closed Valve
Pressure
Switching Valve

Purge Valve

Open
Close
Open
Close
Open
Close

Cold Start
Engine Coolant / Intake Air
Near Same Temp.

Negative
Pressure
Occurs

Fuel Tank &
Charcoal
Canister Leak
Check

VSV (for Canister
Closed Valve), VSV
(for Pressure Switching
Valve) Testing

Abnormal
Vapor Pressure

Normal
Vapor Pressure

3) Monitor

The monitor sequence begins with a cold engine start. The intake air temp. and engine coolant temp. sen-
sors must have approximately the same temperature reading. The ECM is constantly monitoring fuel tank
pressure. As the temperature of the fuel increases, pressure slowly rises. The ECM will purge the charcoal
canister at the appropriate time. With VSV (for pressure switching valve) closed, pressure will continue
to rise in fuel tank.

ENGINE – 1MZ-FE ENGINE

EG-50

189EG34

Open

189EG35

To Intake
Manifold

Open

4) DTC P0440, P0442 (Evaporative Emission Control System Malfunction)

Initially, when the canister closed valve is closed, and the pressure switching valve and the purge valve are
opened, a vacuum is applied to the purge line from the air intake to the charcoal canister and to the evapora-
tor line from the charcoal canister to the fuel tank. Next, the purge valve is closed in order to maintain a
vacuum from the VSV (for EVAP) to the inside of the fuel tank. Then, any subsequent changes in the pres-
sure are monitored by the vapor pressure sensor in order to check for evaporative emission leaks.
If a leak is detected, the MIL (Malfunction Indicator Lamp) illuminates to inform the driver. Also, the
DTC (Diagnostic Trouble Code) can be accessed through the use of a hand-held tester.
For details on the DTCs, refer to the 2002 ES300 Repair Manual (Pub. No. RM911U).

5) DTC P0441 (Evaporative Emission Control System Incorrect Purge Flow)

At a predetermined point, the ECM closed the canister closed valve and opens the pressure switching
valve causing a pressure drop in the entire EVAP system. The ECM continues to operate the VSV (for
EVAP) until the pressure is lowered to a specified point at which time the ECM closed the purge valve.
If the pressure did not drop, or if the drop in pressure increase beyond the specified limit, the ECM judges
the VSV (for EVAP) and related components to be faulty and the MIL illuminates to inform the driver.
Also, the DTC can be accessed through the use of a hand-held tester.
For details on the DTCs, refer to the 2002 ES300 Repair Manual (Pub. No. RM911U).

Content .. 129 130 131 132 ..