The vacuum switching valve aka VSV handles the vacuum pass to the actuator. It usually remains closed until signals from ECU, that is the engine control unit triggers the switch.
What Does a Vacuum Switching Valve Do
A vacuum valve is an apparatus that guides the flow of fluid or air to initiate a vacuum. The applications of this device are controlled by a switch. The vacuum switching valve is generally placed in the engine component or the engine below the intake manifold.
The vacuum switching valve is an important part of an engine as it elongates the intake manifold run. As soon as the ECU signal reaches the switch valve, the vacuum is directed to the actuator shutting the air regulating valve. The ECU manages the valve by affording current to the solenoid coil when predetermined conditions are met.
The vacuum switching valve can increase the speed of the engine by 100 rpm when energized. It grants only a limited amount of air to enter the shut throttle valve when it’s released.
Vacuum switches usually monitor the change in a vacuum. If a change occurs in the gas or liquid level the switch opens or closes as required. Thus these switches are considered pressure switches. They activate in the vacuum edge of the pressure range and they calculate the negative pressure.
There’s a type of switching valve that is named BVSV. BVSV is the short form of Bi-metal Vacuum Switching Valve. It’s usually placed behind the intake on the water bypass outlet. It transfers gas fumes from the canister to the air intake compartment to be charred.
On the other hand, a purge vacuum switching valve is the section of vehicle Evaporative Emission Control that is the EVAP system. It snares the fuel vapors from the tank and stores them in the canister for a limited time.
General Test of a Vacuum Switching Valve
You can conduct some tests to know about these vacuum switch valves chiefly. To do that you can take the valve apart. First, connect the valve ends to the battery according to the switches operating voltage range. Take a tube that matches around the port nearest to the connector. The port connected to the connector is port E and the other end is port F.
When the voltage would be applied to the VSV from the battery, a clicking sound should be heard. After applying the voltage, blow air to the port. The air should flow without any restrictions out of port F. When the voltage is not applied, air shouldn’t flow out of port F.
Toyota Vacuum Switching Valve Test
Toyota vacuum switching valves are very renowned when it comes to reliability. However, the valves may need tests and replacements to avoid possible accidents related to the evaporate emission system.
The vacuum switch valve is placed on the frontal side of the canister. It usually directs a manifold vacuum to the canister as required. The switch opens when the computer wants to transfer fuel vapor to the manifold from the canister.
The switch is actually functioned by the computer and it’s either on or off. It runs on 12V but a 9V battery will be adequate to operate the switch fully. Disconnect the electrical connector and connect a 9V fresh battery to the VSV. As soon as you connect the battery, you should hear a snapping sound that means the switch is snapped closed.
You can use a vacuum pump to do the test in the easiest way. If the switch is working properly, the vacuum standard of the hand pump will drop to zero when the valve releases. To say elaborately, the vacuum switch should be able to hold a 30psi vacuum until the switch opens and when it opens, the vacuum should drop to zero.
How to Tell Vacuum Switching Valve Is Not Working
The vacuum switching valve is a section of exhaust gas recirculation aka EGR. A faulty EGR can indicate a faulty VSV as well. To detect a faulty vacuum switch you can perform the tests noted. Besides a bad VSV means the bad performance of an engine.
You can check the resistance of the VSV. Detach the electrical connector and check for the resistance across the ends. The resistance should be between 33 to 39 ohms at 68 degrees air temperature. Otherwise, the device is bad.
Bad ignition is also the result of a bad VSV. Your car performance would be poor and more power will be consumed. If your vehicles stop suddenly at the time of running, you should check the valves. Dead cylinders and no spark is also a reason to examine the switch. More emissions, stalling, noises from the engine, etc demonstrates a faulty vacuum switch.
Q: How to detach the connector from a vacuum switching valve?
Ans: It depends on the connector. But usually to remove the connector from the valve, just push the connector downwards. While putting the force press the release button and try to pull the connector upholding the release.
The proper function of a vacuum switching valve is very important to provide a healthy output to the vehicle. a slight leak or a bad VSV can result in a serious failure as well as accidents. Hopefully, this article helped you to gather the basic knowledge about the works and doings of a vacuum switching valve.
Also read- How to Bleed a Clutch with a Vacuum Pump