EGR Valve and NOx Emissions
The EGR or exhaust gas recirculation solenoid is controlled by the ECM according to operating conditions. It controls the EGR valve. If the EGR valve is not opening, high NOx emissions will result. This gas is formed by high temperatures in the combustion chamber. The valve provides a regulated flow of inert exhaust gases into the intake manifold. This lowers combustion chamber temperatures. By blending exhaust gas into the chamber, it is kept at an acceptable temperature, (below 2500° F) preventing nitrogen and oxygen production. This excessive NOx results in pollution and smog.