Carbon tank solenoid valve principle:
When it comes to carbon can solenoid valves, it is inevitable to talk about the Fuel Evaporation Emission Control System (EVAP), which is one of the auxiliary control systems for automobile engines and one of the emission control systems for automobile engines. The system is mainly composed of activated carbon tank storage device, fuel evaporation purification control device and fuel tank fuel evaporation control and other components, and the carbon tank solenoid valve is a very important part of it.
The function of the system is to prevent the evaporated gasoline vapor in the car tank from being discharged into the atmosphere, because gasoline is a volatile liquid, and the fuel tank is often filled with vapor at room temperature, so the role of the fuel evaporation control system is to introduce the vapor into combustion and prevent volatilization into the atmosphere. This process plays an important role in the activated carbon tank storage device, because the activated carbon has an adsorption function, when the car is running or turned off, the gasoline vapor of the fuel tank enters the upper part of the activated carbon tank through the pipeline, and the fresh air enters the activated carbon tank from the lower part of the activated carbon tank. After the engine is turned off, gasoline vapor and fresh air are mixed in the tank and stored in the activated carbon tank, when the engine starts, the carbon tank solenoid valve installed between the activated carbon tank and the intake manifold will be opened, and the gasoline vapor in the activated carbon tank will be sucked into the intake manifold and sent to the cylinder to participate in combustion.
In this process, the carbon can solenoid valve is equivalent to a check valve, similar to a faucet, and its opening and closing time is precisely controlled by the engine computer. And its working state, must meet two basic conditions: one is the antifreeze coolant temperature is higher than 60 degrees; the other is the ambient temperature is higher than 5 degrees, otherwise it can not work normally.
Failure phenomenon after damage to the carbon tank solenoid valve:
1. The throttle file is filed, and the smell of gasoline is heard, which is generally caused by the damage of the carbon tank solenoid valve pipeline;
2. The idle speed is high and low, and the acceleration is weak, which is generally caused by the blockage of the air inlet of the carbon tank;
3. It is not easy to start after the engine is turned off, which is generally caused by the normal opening or normal closure of the carbon tank solenoid valve;
4. The refueling cannot be too slow or too fast, generally caused by the drowning of the carbon tank solenoid valve and choking oil;
5. The driving instrument lights up the engine fault light, and the control unit stores the relevant fault codes inside;
6. There is also a phenomenon that is basically normal, that is, the clicking sound from the cabin when traveling, which is actually the sound of the carbon canister solenoid valve working;
7. Abnormal increase in fuel consumption;
8. The mixture is thick or thin, the mixture is concentrated because the carbon tank solenoid valve is always open, and the mixture is because the carbon tank solenoid valve is often open for too long, after the fuel vapor in the carbon tube is sucked, and then inhaled is too much fresh air, and after mixing with the fuel, it will lead to the mixture of thin gas. In short, that is to say, in the case of the carbon tank solenoid valve is always on, it will cause the engine mixture to be concentrated first and then diluted.
Detection method of carbon tank solenoid valve:
1. Blowing method: In general, when the carbon tank solenoid valve is not working, the interior is in a normally closed state, we can remove the fuel vapor pipe on the carbon tank solenoid valve to blow, if it can be blown through, it means that the carbon tank solenoid valve is damaged, and the replacement can solve the fault.
2. Resistance method: use a multimeter to measure the resistance of the carbon tank solenoid valve, and the resistance value is generally around 30 ohms, which means that there is no problem.
3. Test method: use a wire to connect the two pins of the carbon tank solenoid valve, to touch the positive and negative poles of the battery, if you can hear the "click" sound, it means that there is no problem.
4. Test light method: The carbon tank solenoid valve generally has two wires, one is about 12V power line, and the other is the PWM duty cycle signal line controlled by the engine computer. In the case of the vehicle landing, the LED test light is used to measure the duty cycle signal line, and the test light will blink regularly, that is, it represents that the carbon tank solenoid valve wiring harness is normal.
5. You can also unplug the carbon canister solenoid valve plug and fuel vapor pipe in the case of starting the vehicle, touch the carbon can solenoid valve with your hand, if there is suction, it means that the carbon can solenoid valve is often damaged, and it can be replaced to solve.
Well, the above is part of the knowledge about the carbon tank solenoid valve, I hope to be able to help all the riders and maintenance technicians, reduce the daily use of cars and car troubles.