Description & Operation
WARNING: This page does not describe the selected car, but rather 35 other vehicles, including the 1992 Pontiac Trans Sport, 1992 Oldsmobile Silhouette, 1992 Oldsmobile Bravada, 1992 GMC Yukon, and 1992 GMC Vandura Special. However, it is still accessible from the selected car via links, so may be relevant.
The tuning valve (rotary solenoid device) is electrically controlled by the PCM based on RPM and TP signal inputs, for accurate switching capability at optimum switching points to enable either a "split" or "single" plenum condition.
During the low and high end of the RPM range, the PCM de-energizes the valve and enables a "split" plenum condition that provides for peak torque along with increased peak horsepower.
During the mid RPM range, the PCM energizes the valve, thus enabling a "single" tuning plenum condition that provides for mid RPM range peak torque.