Description: The Exhaust Gas Recirculation (EGR) valve and its related components first appeared on automobiles in 1972. The valve may be controlled by vacuum or electronically depending on the year, make and manufacturer of the vehicle. The use of EGR is on the decline since manufacturers began to use fuel injection, which provides more accurate control over the fuel and air mixture.
Purpose:
EGR systems help reduce the level of harmful oxides of nitrogen
emissions (NOx) in the exhaust. This type of emission
increases with combustion temperature. Although at first impression it may appear
counter-productive, the EGR system does this by introducing calibrated amounts of
exhaust gas into the engine’s intake system. Since
the exhaust gas—for the most part—doesn’t burn, it takes up
some of the space in the combustion chamber of the air/fuel
mixture. As a result, combustion chamber temperature drops and so do
NOx emissions.
Maintenance Tips/Suggestions:
EGR systems usually do not require regular maintenance. Signs of a malfunctioning EGR valve
or its related components include engine spark knock under acceleration, rough
idle, stalling, and reduced power. To determine if your
car has an EGR system, refer to the Vehicle Emission Control
Information (VECI) label underneath the hood, which will call out this
emissions subsystem if so equipped. If you suspect a problem with
your vehicle’s EGR system, have it checked
out by a professional technician. A malfunctioning system, if neglected
long enough, can cause engine damage.
