The EGR Valve is the engine part that provides the exhaust gas recirculation. Exhaust gas circulation system is used in gasoline engines as well as diesel engines. The working principle of the EGR system ensures that NOx (nitrogen oxide or nitrogen oxide) emission is reduced by cooling the exhaust gas and sending it back to the cylinders. Some of the exhaust gas is cooled with the help of engine cooling water and sent back to the combustion chamber and reduces the formation of nitrogen oxides or nitrogen oxides by lowering the combustion temperature in the combustion chamber. The vehicle’s ECU (engine control unit) decides the amount of exhaust gas sent back to the cylinders.

The EGR system depends on variables such as engine speed, engine load, injection quantity, intake air quantity and temperature.
Generally, in case of malfunction, the first thing that comes to mind is the EGR valve cancellation process. However, this process not only increases the emission values, but also reduces the efficiency of the engine. A well-functioning exhaust gas circulation system increases the efficiency of the engine. In addition, the system also contributes to fuel economy. For this reason, replacing the EGR valve with a new one will benefit us in the long run.

What Does the EGR Valve Do? What is the Working Principle?
What Does the EGR Valve Do? What is the Working Principle?

Although most of the combustion gases are composed of nitrogen (N2), water vapor (H2O), carbon dioxide (CO2), which we can call harmless, a small part of them consists of harmful and toxic substances such as carbon monoxide (CO), hydrocarbons and nitrogen oxides.

EGR Valve Working Principle

The exhaust gas circulation valve is an electropneumatic valve. If you say what electropneumatic valve means, it means both air and electrically controlled valve. The EGR valve, which is generally located around the engine, may differ depending on the brand. The EGR System is a system that ensures that the fresh air entering the engine mixes with a low amount of cooled exhaust gas. This lowers the combustion chamber temperature and also reduces the amount of oxygen. Since the formation of NOx gases is higher at high exhaust temperatures, lowering the combustion temperature will also reduce the emission values.

*For other parts that affect emission values, you can refer to the Engine exhaust systems page.

When the engine is at low loads, the engine control unit will send a command to open the EGR valve. The valve that opens in line with this command sends some exhaust gas to the intake manifold. This exhaust gas lowers the combustion temperature as described above. As the engine load increases, the system will turn off. When the engine is running at high loads, we want full combustion in order to increase the power. The engine control unit disables the EGR Valve to ensure complete combustion. In other words, the engine control unit cuts the signal, allowing the valve to close.

How to Identify EGR Valve Failure?

If the exhaust gas circulation valve is dirty or broken, some malfunctions will occur in the operation of the engine. The symptoms of the fault are as follows:

  • Low traction on the engine
  • Engine vibration or misfire while driving
  • Jerky operation of the engine
  • Engine not starting

Although the symptoms described above are caused by many reasons, deterioration or contamination of the EGR Valve is one of these reasons.

How to Cancel EGR Valve?

Although we do not recommend it for the reasons explained above, EGR cancellation may be required in some cases. Although EGR cancellation may seem like an application that you can do at home, blinding it mechanically will cause the malfunction lamp to come on and cause the engine to act as if the egr valve is working. If you have to cancel it, it is useful to cancel it together with the software. If you want to cancel it by mechanical means, all you have to do is to remove the valve and put a heat resistant blind gasket under it. There is no need for this special gasket, you can even cut it out of the coke can. The important thing is to put a barrier that will prevent the passage of exhaust gas from a material that will not melt due to the temperature. That’s actually all you have to do. You don’t need to cancel any cable. But you should know that if you cancel the EGR valve, NOx formation will increase. NOx damages are explained below. In order to protect from these damages and to ensure the smooth operation of the engine, you should upgrade the software.

What are NOx gas damages?

Mono nitrogen oxide and NO2 gases produced in the engine react with ammonia, moisture and nitric acid vapors. Inhalation of nitrogen oxide derivatives causes lung and colon cancer, and also has a factor in the formation of diseases such as emphysema, bronchitis and heart diseases. Small particles harm pregnant women and cause premature births.

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Reference: This page is written by Btperformance