The system uses the method of vapor absorption by a carbon adsorber. It is mounted on the rear suspension cross member and is connected by pipelines to the fuel tank and the purge solenoid valve.
The adsorber purge solenoid valve, which switches the system operating modes at the signals of the engine control unit, is located in the engine compartment.
Fuel vapors from the fuel tank are constantly discharged through the pipeline and accumulate in the adsorber filled with activated carbon (adsorbent). When the engine is running, it regenerates (recovery) adsorbent by purging the adsorber with fresh air entering the system under the action of vacuum, transmitted through the pipeline from the inlet pipe to the adsorber cavity when the valve is opened. Since fuel vapor enters the engine intake pipe, the air-fuel ratio in the working mixture changes, which can interfere with the normal operation of the engine. To eliminate the negative consequences of changing the composition of the working mixture, the electronic engine control unit regulates the intensity of the adsorber purge depending on the engine operating mode, supplying a signal with a variable pulse frequency to the valve.
Under certain conditions, the canister purge valve closes (e.g. at idle) or can't work (when the throttle valve is fully opened, insufficient vacuum is created in the intake pipe). In addition, the engine control unit changes the frequency of the pulses that control the canister purge valve when the signals from the oxygen concentration sensors in the exhaust system catalyst indicate that the oxygen content in the exhaust gases is not optimal.
Malfunctions of the fuel vapor recovery system entail idle instability up to engine shutdown, increased toxicity of exhaust gases and deterioration in driving performance of the car.
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