Variable Resonance Induction System (MILLENIA 2.5L & 626 2.5L)
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 2002 Mazda Tribute, 2002 Mazda Protege5, 2002 Mazda Protege, 2002 Mazda Millenia, and 2002 Mazda MX-5 Miata. However, it is still accessible from the selected car via links, so may be relevant.
The Variable Resonance Induction System (VRIS) uses 2 shutter valves in the dynamic chamber to change intake runner effective length depending upon engine RPM. See Fig 1 . To improve torque output at low-to-medium engine RPM, intake runners are opened into a resonance chamber, providing improved airflow to the cylinder. At high engine speed, the shutter valves close, shortening intake runner length and improving high RPM performance. Millenia and 626 models are equipped with 2 VRIS shutter valve actuators and 2 VRIS solenoid valves.