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Evaporative Emission (EVAP) Control System

Purpose, outline

• Prevents release of evaporative gas into the atmosphere.

• The intake manifold vacuum introduces evaporative gas to the intake manifold via the charcoal canister and the purge solenoid valve.

System diagram

U.S.A. and CANADA

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Except U.S.A. and CANADA

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Structure

• The evaporative emission control system consists of the following parts:

U.S.A. and CANADA

Except U.S.A. and CANADA

Purge Solenoid Valve

Purpose, function

• Introduces evaporative gas absorbed by the charcoal canister to the intake manifold.

• The purge solenoid valve opens according to the control signal from the PCM.

Construction

• The purge solenoid valve is located near the catch tank.

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• The purge solenoid valve consists of a coil, spring, and plunger.

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Operation

• According to the control signal from the PCM, the coil is energized and the plunger is operated to open/close the purge solenoid valve.

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• When the purge solenoid valve is open, evaporative gas flows from the charcoal canister to the intake manifold side.

Purge solenoid valve open/closed view

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• For evaporative purge control details, refer to CONTROL SYSTEM. (See PURGE CONTROL [SKYACTIV-G (WITHOUT CYLINDER DEACTIVATION (US))].)

Catch Tank

Purpose, function

• Suppresses pulsation occurring before evaporative gas is inducted into the intake manifold.

Construction

• The catch tank is located near the purge solenoid valve.

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Operation

• When evaporative gas flows from the charcoal canister to the purge solenoid valve, pulsation is suppressed by passing the evaporative gas through the hollowing of the catch tank.

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Charcoal Canister

Purpose, function

• Absorbs evaporative gas flowing from the fuel tank to prevent release of the gas into the atmosphere.

Construction

• The charcoal canister is installed near the main silencer.

• The charcoal canister has activated charcoal to absorb evaporative gas.

U.S.A. and CANADA

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Except U.S.A. and CANADA

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Operation

• When the purge solenoid valve is open, evaporative gas, which is absorbed by the activated charcoal, is released by the intake manifold vacuum and the gas flows to the intake manifold.

U.S.A. and CANADA

Charcoal canister (main)

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Charcoal canister (sub)

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Except U.S.A. and CANADA

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Canister Vent (CV) Solenoid Valve

U.S.A. and CANADA

Purpose, function

• Seals the atmosphere side of the charcoal canister during EVAP leak check monitoring.

Construction

• Included in the charcoal canister (sub).

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• The CV solenoid valve consists of the armature, coil, O-ring, plunger, valve seal, and the spring.

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Operation

• According to the control signal from the PCM, the coil is energized and the plunger opens/closes the CV solenoid valve.

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• By closing the CV solenoid valve, the outlet opening to atmosphere of the charcoal canister (sub) is blocked.

CV solenoid valve open/close figure

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Pressure Control Valve

U.S.A and CANADA

Purpose, function

• Prevents fuel tank damage by controlling the vacuum applied to the fuel tank from the charcoal canister while the purge solenoid valve is open.

Construction

• The pressure control valve is located near the charcoal canister (main).

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• The pressure control valve is integrated with the evaporative hose.

• The pressure control valve consists of the spring diaphragm, and orifice.

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Operation

• The pressure control valve is divided into 2 chambers by a diaphragm, and operates in accordance with the difference in pressure between the evaporative gas passage pressure and the barometric pressure via the charcoal canister (sub).

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• When the evaporative gas pressure increases, the pressure control valve opens. As a result, evaporative gas is introduced from the tank side to the charcoal canister side.

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• When the purge solenoid valve is open, the pressure control valve is closed to suppress the intake manifold vacuum applied to the fuel tank.

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Fuel Shut-off Valve

U.S.A and CANADA

Purpose, function

• Prevents fuel from flowing to the charcoal canister during tight turns or vehicle rollover.

• Releases evaporative gas to the charcoal canister.

• While refueling, the fuel shut-off valve closes to prevent a fuel overflow.

Construction

• The fuel shut-off valve is built into the fuel tank.

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• The fuel shut-off valve consists of a float, O-ring and spring.

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Operation

• While refueling or due to fuel sloshing, the float is flooded with fuel and the floating force causes the valve to close. Also, during a vehicle rollover, the valve closes due to balance between the float gravity and spring.

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Rollover Valve

Purpose, function

• Prevents fuel from flowing into the evaporative gas passage during sudden cornering or vehicle rollover.

Construction

• The rollover valve is built into the fuel tank.

U.S.A. and CANADA

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Except U.S.A. and CANADA

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• The rollover valve consists of a float, O-ring and spring.

U.S.A. and CANADA

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Except U.S.A. and CANADA

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Operation

• The rollover valve utilizes a combination of float weight, spring force, and buoyancy. When the float is immersed in the fuel, the float (valve) closes to block the sealing surface of the passage.

U.S.A. and CANADA

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Except U.S.A. and CANADA

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Check Valve

Purpose, function

• The check valve adjusts and maintains the pressure in the fuel tank at a constant pressure.

Construction

U.S.A. and CANADA

• The check valve is built into the rollover valve.

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Except U.S.A. and CANADA

• The check valve is located on the fuel tank.

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Operation

• The valve moves in response to the difference in air pressure between the fuel tank side and the atmospheric side, thereby changing the path of airflow.

• When the pressure in the fuel tank becomes negative due to fuel consumption or other factors, the path opens, drawing atmospheric air into the fuel tank.