Any car that has a combustion engine will have a purge valve because a purge valve is a standard feature of any automobile, and when the purge valve gets bad, your car can get stuck anywhere at any time.
A faulty purge valve causes a vacuum leak, which affects the vehicle’s mileage and speed. A defective purge valve is tested with a multimeter by measuring resistance and continuity to see how well it is working. This article will give you a complete explanation of How to Test a Purge Valve with a Multimeter.
In addition, we will talk about the following issues:
- The effects of a faulty canister purge valve
- Does the purge valve have to click?
- Can a fault purge valve cause a misfire?
What is a purge valve?
A “purge valve” is a safety device on the furnace. The purge valve’s purpose is to release any gas that could accumulate inside the furnace. This gas buildup can be hazardous because it can cause explosions or fires. The EVAP purge valve traps fuel vapors inside a charcoal canister during combustion to keep them from leaking into the atmosphere.
This gasoline vapour is released into the engine for combustion when the Powertrain Control Module (PCM) sends a signal to the purge valve, serving as a backup fuel supply.
Problems With The Purge Valve
A purge valve might have many issues.
- Purge Valve Stuck Closed
- Purge Valve Stuck Open
- Power Terminal Problem
Purge Valve Stuck Closed
The engine misfires and is difficult to start when the purge valve is stuck closed.
However, the PCM quickly recognizes this issue and the dashboard’s engine lights turn on.
Purge Valve Stuck Open
The amount of gasoline vapor discharged into the engine is uncontrollable when the purge valve is stuck open. Because the automobile is still functioning, this also leads to engine misfiring and starting issues, which makes it harder to notice.
Power Terminal Problem
Accordingly, when faulty, the purge valve doesn’t get the proper instructions from the PCM to carry out its tasks.
It is easier to conduct the necessary checks on this and other auto parts with the aid of a multimeter.
How To Test Purge VALVE WITH MULTIMETER
Set your multimeter’s dial to Ohms, place the probes on the purge valve’s power terminals, and check for resistance between the terminals to test your purge valve. A defective purge valve has to be replaced if the measurement is below 14 Ohms or above 30 Ohms.
Method 1: Continuity Test
Most purge valves are tested for continuity to make sure that the metallic or copper coil running from the positive to the negative terminals is okay. If this coil is defective, the purge valve won’t function. Follow these instructions to perform the test.
1. Remove the purge valve from the vehicle.
You must unplug your purge valve from the automobile in order to properly access it and check for continuity.
Make sure the car has been off for at least 30 minutes before doing this.
The intake and outlet hose clamps for the purge valve must be unscrewed, and it must also be disconnected at the power terminal. The outlet line connects to the engine, while the input hose is connected to the fuel tank.
2. Set the Continuity Mode on Your Multimeter
Select continuity mode on your multimeter’s dial, which is typically indicated by a “sound wave” indicator.
Place the two multimeter probes on top of each other to hear a beeping sound to determine if this mode is configured properly.
3. Multimeter Probes Should Be Placed On The Terminals
Once your multimeter has been properly set, put the probes on the power terminals of the purge valve.
4. Evaluate Results
Now, if the multimeter does not produce a beeping sound when you place the probes at the power terminals, then the coil within the purge valve is broken, and the entire valve has to be replaced. If the multimeter produces a beeping sound, you move on to doing more tests.
METHOD 2: RESISTANCE TEST
If the resistance between the positive and negative terminals is too low or too high, the purge valve may not be functioning correctly.
The multimeter also helps you make a diagnosis by following these procedures.
1. Disconnect The Purge Valve From The Car
You completely unplug the purge valve from the vehicle, just as when you check for continuity.
In addition to releasing the valve at the power terminal, you also detach the hose clamps.
2. Set your Ohms to Multimeter
You set your multimeter to Ohms in order to measure the resistance in your purge valve. You set your multimeter to Ohms in order to measure the resistance in your purge valve.
On a multimeter, this is usually denoted by the Omega symbol ().
The multimeter screen should show “O.L,” which stands for open loop, or “1,” which denotes an infinite reading, to show that it is correctly configured.
3. Multimeter probe positions
Simply connect the multimeter probes to the power terminals of the purge valve
4. Evaluate the Result
You should pay close attention here. Depending on the type, a healthy purge valve should have a resistance of between 14 and 30 ohms.
Your purge valve needs to be replaced if the multimeter shows a value that is either higher or lower than the appropriate range. These additional methods don’t require a multimeter, but they do help in diagnosing a stuck open or stuck closed issue.
METHOD 3: MECHANICAL TESTS
A purge valve click test and a purge valve vacuum test are two examples of mechanical click testing.
PURGE VALVE CLICK TEST
The purge valve click test helps determine if a valve is stuck closed.
A signal is often delivered to the purge valve at intervals while the engine is running, causing it to open and let gasoline vapor in.
When the valve opens, a clicking sound is made, and this is what you want to listen for.
Follow these instructions to conduct a basic test.
- If the value falls within this range, then continue to the next steps.
- Once the purge valve has been disconnected from your vehicle, just connect it to the battery to make it a power source. Alligator clips, a 12-volt battery, and your ears are all that are needed for this straightforward setup.
- Place two alligator clips One end of each alligator clip should be placed on one of the power terminals of your purge valve, and the other end should be placed on one of the battery posts.
- This means one alligator clip is attached to the positive battery post and the other is attached to the negative post.
- Once the clips are properly connected, a good purge valve makes a clicking noise. The purge valve opening causes the clicking sound, as was previously stated.
PURGE VALVE VACUUM TEST
The vacuum purge valve test helps identify a stuck open issue. The purge valve won’t do its job of providing the engine with the proper amount of fuel vapour if it is leaking.
- You also need a portable vacuum pump.
- The outlet, in which fuel vapoursexito the engine, must first be connected to the vacuum pump.
- The hose for the vacuum pump must be between 5 and 8 inches long in order to fit properly.
- As soon as the hose is securely attached, turn on the vacuum pump and check to see that the pressure is between 20 and 30 hPa. The highest vacuum pressure possible is 30 Hg, which corresponds to a complete vacuum (rounded up from 29.92 Hg)
- The purge valve won’t do its job of providing the engine with the proper amount of fuel vapors if it is leaking.
- Wait for two to three minutes while keeping a careful eye on the pump’s suction pressure.
- If the vacuum pressure drops, the purge valve has to be replaced because it is leaking. If it doesn’t, the purge valve is not leaking.
- If the pressure does not go down, you can try connecting the purge valve to a power source, such as the car battery, to get it to open.
- When the valve opens, which is indicated by a click, you anticipate seeing the vacuum pressure drop to zero.
- The purge valve is working properly if this occurs.
Conclusion
An essential part of an automobile is the solenoid valve. If you observe any of the issues mentioned, you should bring the car in right away for service. If you wish to test the canister on your own, just follow the instructions with the multimeter, and it will tell you if you have a bad valve or not!
You might wish to verify since we showed you how to test the purge valve using a multimeter. You might wish to consult a guide on the best multimeter and choose the one that best suits your testing requirements.
This informational piece is meant to be helpful. Good fortune!