When engine speed is less than 4,100 rpm
• The PCM energizes the closed-side circuit of the variable intake-air shutter valve actuator, closing the variable intake-air system shutter valve to enhance the inertia charging effect in the engine low speed range.
When engine speed is 4,100 rpm or more
• The PCM energizes the open-side circuit of the variable intake-air shutter valve actuator, opening the variable intake-air system shutter valve to enhance the inertia charging effect in the engine high speed range.