EGR Valve Introduction:
The EGR valve is one of the important components of the exhaust gas recirculation system, which will send some of the exhaust gases discharged from the engine back into the intake manifold and re-enter the cylinder with the fresh mixture to participate in combustion. Because the exhaust gas contains a large number of carbon dioxide and other polyatomic gases, although carbon dioxide and other gases can not be burned, but because of its high specific heat capacity and can absorb a large amount of heat in the combustion chamber, so that the maximum combustion temperature of the mixture in the cylinder is reduced, thereby reducing the amount of nitrogen oxides and energy saving and emission reduction.
As for the role of the EGR valve, it is to control the amount of exhaust gas entering the intake manifold, so that a certain amount of exhaust gas flows into the intake manifold for recirculation. And its principle is also relatively simple, colloquially speaking, it is equivalent to a faucet, but the amplitude of opening or closing is controlled by the engine ECU computer, when the valve is opened, the exhaust gas enters the combustion chamber, and when the valve is closed, the exhaust gas does not enter the combustion chamber and is discharged through the exhaust pipe. Since the EGR valve is electronically controlled by the ECU, it can accurately control the amount of exhaust gas entering the cylinder, thereby reducing excessive exhaust gases entering the engine and affecting normal operation. In addition, the EGR valve generally starts to work at medium and high speeds, and basically does not participate in the work in the low speed or idle state.
Fault phenomena after damage to the EGR valve:
The damage of EGR valves can be roughly divided into two categories, namely normally open and normally closed.
If the EGR is in the normally open position, the vehicle will have idle instability, or even stall, high fuel consumption, insufficient power and other fault phenomena; and if the EGR is in the normally closed position, the vehicle will have excessive emissions, high exhaust temperature, shortened water temperature heating period and other fault phenomena. Whether the EGR valve is normally closed or normally open, the driving instrument lights up the engine fault light for early warning and the associated fault code is stored inside the engine control unit.
Detection method of EGR valve:
EGR valve generally has 5 wires, pin one and pin five for the power supply and negative pole line of the EGR valve motor, the use of multimeter measurement of two pins should get a voltage of about 12V, that is, battery voltage, and the resistance of these two pins should be measured at about 10 ohms;
Pin two is the sensor power line of the EGR valve, and there should be a 5V voltage when measuring with a multimeter, that is, the ECU power supply;
Pin three is the sensor signal line, measured in the state where the EGR valve is not working, and its signal voltage should be about 0.82V;
Pin four is the negative electrode of the EGR valve sensor, and its voltage should be 0V when measured with a multimeter. If there is no problem with the measured wire voltage, it means that the EGR valve is damaged and can be replaced.
In addition, you can also remove the EGR valve, the battery positive and negative poles directly connected to pin one and pin five above, if the EGR has the action of opening and closing, it means that the EGR valve has no problem, then it is necessary to focus on checking the engine control module and the sensor signal line, power line and iron wire.
If you suspect that the EGR has a normally open fault, then you can remove the EGR, and then find a thicker piece of paper to block the exhaust gas flow hole above the EGR valve, if the fault phenomenon disappears, it means that the EGR is damaged, and it can be replaced directly.
Well, the above is part of the knowledge about the working principle of the EGR valve, the fault phenomenon after damage and the detection method, and I hope it will be helpful to all the riders and maintenance technicians.