Exhaust Gas Recirculation: Description and Operation
TURBOCONTROL VENT SOLENOIDS EGR
The Exhaust Gas Recirculation (EGR) system recirculates exhaust gas to the engine air intake under average vehicle driving conditions, to reduce combustion temperatures and exhaust gas NOx content. The amount of recirculation varies from zero with a cold engine to a fixed flow rate with an engine at normal operating temperature, intermediate load, and 1500 rpm minimum engine speed. The flow increases steadily as coolant temperature rises past 104°F. The system employs a control solenoid, triggered by the ECA and sensor system.
The ECA will disable the EGR system under conditions of zero throttle opening, full throttle, low coolant temperature, low engine speed, transmission in neutral, and system malfunction. The ECA disables the EGR system by opening the EGR vent solenoid.
The EGR control solenoid and the EGR vent solenoid are packaged together. The control solenoid's function is to actuate the EGR system by allowing vacuum stored in the vacuum reservoir to reach the EGR valve. The vent solenoid relieves the vacuum at the EGR valve when the control solenoid closes.
NON-TURBO
BACK PRESSURE VARIABLE TRANSDUCER EGR
The Exhaust Gas Recirculation (EGR) system recirculates exhaust gas to the engine air intake under average vehicle driving conditions, to reduce combustion temperatures and exhaust gas NOx content. The amount of recirculation varies from zero with a cold engine to a fixed flow rate with an engine at normal operating temperature, intermediate load, and 1500 rpm minimum engine speed. The flow increases steadily as coolant temperature rises past 158°F. The system employs a control solenoid, triggered by the ECA and sensor system.
The ECA will disable the EGR system under conditions of zero throttle opening, full throttle, low coolant temperature, low engine speed, transmission in neutral, and system malfunction. The ECA disables the EGR system by closing the EGR control solenoid.