A crucial part of a carโs engine management system, the EGR or exhaust gas recirculation valve recirculates gases through the intake, increasing efficiency, reducing fuel consumption, and lowering harmful emissions. Here, weโll discuss what the EGR system is, what it does, and how to know when itโs about to fail.
How do EGR Valves Work?
Nitrogen makes up almost 80% of our air. However, when nitrogen is exposed to high temperatures in an engineโs combustion chamber, this typically inert gas becomes highly reactive-creating harmful oxides that are then passed into the atmosphere.
To minimize pollution, an EGR valve allows a certain quantity of gases to recirculate through the system, changing the chemical composition of the air going into the engine.
Because thereโs less oxygen, the mixture burns more slowly, reducing the combustion chamberโs temperature as well as nitrogen oxide production. EGR valves are used in smaller engines and diesels to improve knock tolerance and combustion efficiency.
Is EGR Valve Removal a Good Idea?
EGR deletes are a popular modification among automotive enthusiasts. Aftermarket parts, known as EGR delete kits, are used to remove the vehicleโs exhaust gas recirculation system in hopes of a performance increase.
The recirculation of exhaust gases displaces some oxygen from the combustion chamber, slightly decreasing the engineโs performance. Despite this, the EGR system is still an important part of the engines found on modern cars, trucks, and SUVs.
EGR Valve Types
Though several valve types are used, they can be classified as.
- A diesel high-pressure valve diverts dirty exhaust gases before they enter the particulate filter and create sludge. These gases are recirculated to the intake manifold via pipes or holes drilled in the cylinder head, with secondary valves used to create enough vacuum pressure.
- Diesel low-pressure valves divert exhaust gases after they pass through the particulate filter. The gases are passed back to the intake manifold through pipes.
- Gas EGR valves divert gases in much the same way as their high-pressure diesel counterparts. As cylinders depress, a vacuum is created, and exhaust gases are drawn in. The EGR valveโs closing and opening regulates the flow of gas.
- Vacuum-operated EGR valves use solenoids to vary vacuum pressure, which causes them to open and close.
- Digital valves include a stepper motor or solenoid as well as a sensor. These valves get signals from the ECU or engine control unit, thereby regulating the flow of exhaust gases.
Now that weโve discussed the various types of EGR valves, letโs get into the reasons why they fail.
The Causes of EGR Valve Problems
EGR valves work in hot, high-stress environments. While wear and tear certainly play a role, the primary cause of EGR valve malfunction is the gradual buildup of carbon in intake passages.
With time, tubes, gas channels, and valve plungers will become clogged, causing them to stick in a closed or open position. Diaphragm leaks or ruptures are another cause of EGR valve failure.
Here are a few signs to look for in a failing EGR valve:
- An illuminated check engine light.
- Engine performance problems like low power, choppy idling, and sluggish acceleration.
- More raw fuel in vehicle emissions, which brings a notable decrease in fuel efficiency and engine performance.
- Engine knocking due to increased nitrogen oxide emissions and higher temperatures within the combustion chamber.
Because there are so many kinds of EGR valves, itโs best to follow the procedures set forth in the vehicleโs ownerโs manual. If youโre unsure of how to clean or replace a faulty valve, bring your vehicle to a local auto service center for help.
