Power Valve Control System

Fig. 96 Power Valve Operation:

CIRCUIT OPERATION
The intake system is supplied with a valve that shuts off one side of the intake passage to each cylinder. Nissan calls this system NICS.
At low engine speed or load condition, the power valve is closed. This increases the intake air velocity. This produces a swirl effect in the combustion chamber promoting better vaporization of the A/F mixture. This effect causes the mixture to burn faster, improving fuel economy and engine stability.
During high engine load or rpm's, the power valve opens. This allows less resistance in the intake flow, increasing intake capacity. The power valve is controlled by the ECU via the power valve control solenoid. The ECU supplies the ground circuit for the solenoid.

Fig. 142 Vacuum Control Solenoid:

POWER VALVE CONTROL SOLENOID
The ECU supplies the ground circuit to the power valve solenoid, energizing it. This redirects vacuum from the source port and vent port to the source port and valve port, applying vacuum to the valve.

Fig. 95 Power Valve Control System:

Refer to the figure for power valve operation.