Variable Induction System: Description and Operation

Fig. 8 Manifold Tuning Valve:

MANIFOLD TUNE VALVE (MTV)
The valve opens a crossover passage in that connects both sides of the intake manifold plenum (Fig. 8). It is an rotary solenoid.

The PCM controls the MTV solenoid. The manifold tuning valve optimizes acoustical tuning of the intake system during wide open throttle operation throughout the RPM range.