Description & Operation

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2003 Nissan Xterra, 2003 Nissan Sentra, 2003 Nissan Pathfinder, 2003 Nissan Murano, and 2003 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.

This system has a swirl control valve in the intake passage of each cylinder. While idling and during low engine speed operation, the swirl control valve closes. Thus the velocity of the air in the intake passage increases, promoting fuel vaporization and producing a swirl in the combustion chamber. Because of this operation, this system tends to increase the burning speed of the gas mixture, improve fuel consumption, and increase the stability in running conditions. Also, except when idling and during low engine speed operation, this system opens the swirl control valve. In this condition, this system tends to increase power by improving intake efficiency via reduction of intake flow resistance, increasing intake flow. The solenoid valve controls swirl control valve's shut/open condition. This solenoid valve is operated by the ECM.

The swirl control valve control solenoid valve responds to signals from the ECM. When the ECM sends an ON (ground) signal, the solenoid valve is bypassed to apply intake manifold vacuum to the swirl control valve actuator. This operation closes the swirl control valve. When the ECM sends an OFF signal, the vacuum signal is cut and the swirl control valve opens.

The swirl control valve control vacuum check switch detects vacuum signal to the swirl control valve, and sends ON or OFF signal to the ECM. When vacuum is supplied to the valve, the swirl control valve control vacuum check switch sends OFF signal to the ECM. The swirl control valve control vacuum check switch is not used to control the engine system, it is used for on board diagnosis.