Town Car V8-281 4.6L SOHC (1991)
Vacuum Controller: Description and Operation
VACUUM REGULATOR VALVES
The Vacuum Regulator Valve (VRV) is located within the vacuum hose routing or harness assembly. The VRV is designed to provide a constant vacuum
output. There are two types of VRV's.
2-Port Vacuum Regulator
The 2-Port Vacuum Regulator Valve maintains a constant vacuum output signal, while source vacuum is greater than the pre-set calibration of the valve.
If the input source vacuum falls below the pre-set calibration, the 2-Port VRV output vacuum signal will be equal to the input source vacuum.
3-Port Vacuum Regulator
Vacuum Regulator (3 & 4 Port)
The 3-Port and 4-Port regulators are used to control the vacuum signal to the vacuum advance unit of the distributor. During engine idle, the manifold
vacuum input signal is limited to a constant output signal.
Once the engine is off-idle, the output signal will equal the spark port.
