Exhaust Gas Recirculation: Description and Operation

This system controls flow rate of EGR led from exhaust manifold to intake manifold. The opening of the EGR bypass passage in the EGR volume control valve changes to control the flow rate. A built-in step motor moves the valve in steps corresponding to the PCM output pulses. The opening of the valve vanes for optimum engine control. The optimum value stored in the PCM is determined by considering various engine conditions. The EGR volume control valve remains closed under the following conditions.
- Engine stopped
- Engine starting
- Engine idling
- Low engine coolant temperature
- Excessively high engine coolant temperature
- High engine speed
- Wide open throttle
- Low battery voltage