EGR or Exhaust Gas Recirculation is a system for reducing pollution from the exhaust gas of both gasoline and diesel car engines by mixing some of the exhaust gas with oxygen in the combustion chamber to reduce the level of toxic gas emitted through the exhaust pipe.
The engine’s combustion chamber at temperatures of 2,000 to 2,500 ° F produces highly toxic gas, nitrogen oxides(NOx), and carbon monoxide. This gas will drop if the temperature of combustion chamber is not too high. Therefore, cars without the EGR system will release such toxic gas directly into the atmosphere, affecting people and the environment.
The reason for the high temperature of the combustion chamber is the presence of large amounts of oxygen as the combustion fuel mixture. While the engine is running normally, the ECU determines the low oxygen or lean mixture. But when the driver needs engine power, for example, when accelerating, the ECU adjusts the oxygen mixture more. That causes more toxic gas.
The EGR system works by mixing some of the exhaust or inert gas with oxygen to reduce the concentration of the fuel mixture in the combustion chamber. The benefits are lower temperature, less black smoke, less toxic gas. But the disadvantage is reduced engine power.
When EGR re-regulates the exhaust, the exhaust will flow through a valve. That is the EGR valve we talked about it.
The electric EGR valve acts to trap or allow gas to flow through the ECU’s control.
When exhaust flows through the EGR valve for a long time, such as 50,000 to 70,000 miles, exhaust soot will accumulate at the valve. This valve will not be able to move if the amount of soot is too high.