Description & Operation
Vacuum Delay Valves (VDV) are used on various parts of the engine to provide for gradual application or release of vacuum to engine or emission-related devices.
These valves may be one-way or two-way delay valves, depending upon application. Although each valve is named for a given system, it may be used elsewhere.
NOTE:
Be sure valve is installed in correct direction, or engine will run rough, ping or use excessive fuel.