EVAPORATIVE EMISSION CONTROL SYSTEM

SYSTEM DIAGRAM

<134, 135>

<4G1>

The fuel vapours (HC: hydrocarbons) that are created in the fuel tank are initially absorbed by the activated charcoal in the canister. While the engine is running, the inlet manifold vacuum draws the fuel vapour (stored in the canister) together with the air-fuel mixture into the combustion chamber for combustion.
The engine-ECU or engine-A-M/T-ECU actuates the purge control solenoid valve under duty cycle control in order to draw in a amount of fuel vapours in accordance with the driving conditions.
While the engine is operating in the low-load range where the intake air amount is low, the intake of fuel vapours from the canister is stopped or the intake amount is decreased in order to minimize the fluctuation in the air-fuel ratio, thus stabilizing the exhaust emission level.
For backflow prevention at the turbocharger, the check valve is used between the purge control solenoid valve and the canister <4G1>.

PURGE CONTROL SOLENOID VALVE

The purge control solenoid valve regulates the amount of fuel vapours that are drawn from the canister into the inlet manifold through duty cycle control.
The engine-ECU or engine-A-M/T-ECU controls the actuation of the purge control solenoid valve in accordance with the signals provided by the crankshaft position sensor and the manifold absolute pressure (MAP) sensor <134, 135> or air flow sensor <4G1>. The fuel vapour intake amount is proportionate to the ON duty cycle ratio.