EGR Valve: Description and Operation

LINEAR EGR VALVE

Linear EGR Valve:

The main element of the system is the linear EGR valve. The EGR valve feeds small amounts of exhaust gas back into the combustion chamber. With the fuel/air mixture diluted by the exhaust gases, combustion temperatures are reduced.

OPERATION

Operation:

The linear EGR valve is designed to accurately supply EGR to an engine independent of intake manifold vacuum. The valve controls EGR flow from the exhaust to the intake manifold through an orifice with a Powertrain Control Module (PCM) controlled pintle. During operation, the PCM controls pintle position by monitoring the pintle position feedback signal. The feedback signal can be monitored with a scan tool as EGR position sensor. The EGR position sensor should always be near the commanded EGR position (Desired EGR). The PCM uses information from the following sensors to control the pintle position:
^ The Engine Coolant Temperature (ECT) sensor
^ The Throttle Position (TP) sensor The Mass Air Flow (MAF) sensor

The linear EGR valve is usually activated under the following conditions:
^ Warm engine operation
^ Above idle speed