Exhaust Gas Recirculation: Description and Operation

DESCRIPTION
This Exhaust Gas Recirculation (EGR) System consists of the EGR Duty Solenoid, Vacuum Tank, Vacuum Regulator, and Vacuum Switching Valve (VSV) for cutting EGR, and is controlled by Engine Control Module (ECM) through EGR Duty Solenoid. The optimum EGR volume is determined by ECM based on three main signals (Engine RPM, intake air volume, Engine Coolant Temperature (ECT)) to achieve more precise EGR control.









FAIL SAFE OPERATION
1. The vacuum source for Exhaust Gas Recirculation (EGR) is taken from the Throttle signal. While the Engine is running idle, the Engine Control Module (ECM) controls the Duty Solenoid to allow no signal vacuum to EGR Valve, thus ensuring stable Engine starting and idling.
2. Short-circuit in Duty Solenoid. The Duty Solenoid of this EGR system is the "Normal Closed" type. If it is short-circuited, the signal vacuum is given to EGR Valve continuously. If the Duty Solenoid fails, the ECM will send signals to Vacuum Switching Valve (VSV) ("ON" to "OFF"), to cut the EGR.
3. Short-circuit in VSV. The VSV equipped for cutting EGR, is the "Normal Closed" type, and so even if the VSV is short-circuited, no vacuum is applied to EGR Valve.