•  To open the EGR valve and increase the EGR amount, increase the EGR solenoid valve control duty valve to increase the vacuum applied to the EGR valve. To close the EGR valve to decrease the EGR amount, increase the EGR control solenoid valve control duty valve to decrease the vacuum applied to the EGR valve.

•  When the PCM energizes the intake shutter solenoid valve during the exhaust gas introduction at low engine speed, the vacuum passage is opened and vacuum is applied to the intake shutter valve actuator. Due to this, the intake shutter valve is closed and vacuum is generated downstream of the intake manifold after the intake shutter valve, realizing easier introduction of the exhaust gas to the combustion chamber.