Engine speed approx. 3,750 rpm or less and engine coolant temperature approx. 63°C {145 °F} or less (variable tumble shutter valve is closed)
• Intake manifold vacuum is applied to the variable tumble shutter valve actuator by the operation of the variable tumble solenoid valve, closing the variable tumble shutter valve. At this time, the intake passage is narrower than normal, increasing intake airflow speed and also creating a powerful air tumble in the combustion chamber.
