If you have ever wondered how to test purge valve with multimeter, then this article is for you. This article talks extensively about the symptoms of a damaged purge valve, the testing procedures and required tools, and everything you need to know about a purge valve.
Before looking into “how to test purge valve with a multimeter,” it is crucial to understand what a purge valve is and what it is used for.
The purge valve is an essential device in cars with combustion engines. It forms a component of EVAP – Evaporative Emission Control System in most vehicles.
This system is concerned with trapping toxic fuel vapors in the fuel tank and preventing them from leaking out to the atmosphere or the vehicle. It works by storing the vapors in a charcoal canister temporarily and sending them out to the combustion chambers to be converted to fuel.
The purge valve serves as a control switch between the canister and the vehicle’s engine. It acts by regulating the amount of fuel vapor that leaves the canister to the engine.
In modern vehicles, the purge valve is electronic-operated. As soon as the ignition is on, the purge valve powers up, and when it is off, the purge valve shuts down as well.
Usually, the purge valve stays open while the engine is ignited, and it closes when the engine is turned off. However, in cases where the purge valve is not opening or closing well, it is regarded as being damaged.
This is usually indicated on the dashboard by the “Check Engine Warning Light.” When this happens, to know the exact condition of the purge valve – whether it is stuck open or closed, you need to test it with a multimeter.
A multimeter is a multipurpose tool. It can be used to measure voltage, resistance, and electric current. For example, in a purge valve, the resistance between the terminals is measured with a multimeter.
How to test purge valve with multimeter
Although, there are slight variations in different car models. The basic principle involved in testing the purge valve is the same. Here is an extensive guide on how to test your purge valve with a multimeter.
1. Turn off the Engine
The first thing you should do before testing your purge valve is to turn off your engine. Then, leave it for 15 to 30 minutes before you begin your testing.
2. Identify the Location of the Purge Valve
Next, locate the position of the purge valve in your car. The purge valve is usually inside the charcoal canister, and you can find the canister behind the muffler or silencer on its top.
If you have problems getting to this location, kindly refer to your vehicle’s manual for further instructions.
3. Rearrange the cables
Firstly, disconnect the harness with two pins attached to the EVAP system. Then, connect it to the adapter cables of the multimeter.
These adapter cables usually come with the testing kit. In the end, the terminals of the purge valve should be connected to the adapter cables of the multimeter.
4. Measure the Resistance
To know if the valve is faulty or not, you need to test for the resistance using the multimeter. The standard resistance range of values is between 22 ohms to 30 ohms.
If you record any valve below 22 ohms or above 30 ohms, you need to get a valve replacement. You can replace the purge valve right away if you have a replacement.
Else, remove the adapter cables and connect the harness back if you don’t have one yet.
What Are The Symptoms Of A Damaged Purge Valve?
When a purge valve gets damaged, it causes many problems for the car’s emission control system. As a result, the emission output of the engine is also affected.
However, several indicators give you the awareness of a damaged purge valve. Here are the signs that tell you that your purge valve is damaged:
1. Engine Light
Your engine light turned on might indicate several things, and a damaged purge valve is one of them. The car engine controls the valve, so whenever there’s a problem with the valve, the engine light goes on.
For example, when higher or lesser fuel vapors are detected, specific error codes and warnings are displayed. This feature is always to check for and know if your valve is still in good condition.
2. Engine Issues
When you start experiencing rough idles with your engine, then your purge valve is damaged – either it doesn’t close properly, or it is stuck open. If the valve doesn’t close properly, fuel vapors are released into the atmosphere, which affects the air to fuel ratio.
This will result in difficulty in powering up the engine or rough and inconsistent acceleration while driving.
3. Reduction in Gas Mileage
The purge valve is an essential element of EVAP – a car’s Evaporative Emission Control System. When it is damaged, it affects the functioning of the EVAP system.
As a result, the fuel vapors are not stored in the charcoal chamber; instead, they are released into the air. Eventually, the vapor leakage results in increased fuel combustion and reduced gas mileage.
4. Failure in the Emissions Tests
The EVAP system is tasked with preventing the fuel vapors from leaving the engine and getting released into the air. In a flawed EVAP system, toxic hydrocarbons and fumes are released into the air from the exhaust pipe.
This makes the vehicle fail the emissions assessment.
5. Pressure Buildup
A damaged purge valve will cause the accumulation of fuel vapors inside the vehicle due to poor emissions. This vapor accumulation leads to pressure buildup.
If this buildup persists, it can destroy the rubber seals and gaskets. When these components are destroyed, oil spillage occurs from the emission system into the engine. This can cause severe harm to the engine.
FAQs on how to test purge valve with multimeter
Can I drive with a defective purge valve?
Yes, you can drive your vehicle even if the purge valve is damaged. However, it can damage the engine entirely as well as the other parts in the car.
Also, you are contributing to pollution by driving a car with a damaged purge valve. Toxic fumes are released into the air from the exhaust pipe due to poor emission. These gases are not fit to be inhaled in the environment.
Another issue you will experience with a faulty valve is a reduction in the gas mileage. Thus, it’s advisable that you fix the problem in time to avoid more complications.
How do I know my purge valve is malfunctioning?
If your purge valve is faulty, there are specific signs your vehicle will exhibit. When you start noticing these signs, you should know that your car needs a new purge valve. Some of the symptoms are:
- Rough Idling.
- Difficulty powering up the engine.
- The engine light turns on.
- Uneven and inconsistent acceleration while driving.
- Reduced Gas Mileage.
- Loud purge valve noise.
- Failed Emission Tests.
- Damaged Gaskets.
- Engine Misfiring.
How do I test my purge valve?
There are two ways in which you can test your purge valve to know whether it is faulty or not. You can either check the valve with a vacuum pump or a multimeter. The steps involved in using a multimeter have been described above.
Is there any difference between a canister valve and a purge solenoid?
No, there are no differences between them. The purge solenoid is another name for a purge valve. So, you can use both terms interchangeably.
What are the causes of a faulty purge valve?
The purge valve of a car is designed to last for as long as the vehicle exists. However, several factors can amount to it getting damaged. Environmental factors, wear and tear as a result of constant use, among others, can damage your purge valve.
How do I clean my purge valve?
There are two methods of cleaning a canister valve. The first involves cleaning the valve without opening it, while the other method requires expertise because you need to open up the valve.
So, if you don’t have the technical know-how, it is advised that you avoid the deep cleaning.
Below are the steps on how to clean your valve without opening:
- Pour a good quantity of carburetor cleaner into the two tubes of the valve.
- Close both ends with your hands and shake.
- With the ends still covered, leave the cleaner in the tubes for some minutes.
- Remove your hands and allow the liquid to drain out from the tubes. Depending on how dirty the hose is, the color could be pretty or extremely dark. You can repeat the procedures till you are sure all the dirt is removed. If the liquid comes out clean, then your valve isn’t clogged with dirt. So, there might be another problem.
Can a damaged purge valve cause a misfire?
Yes, a damaged purge valve can undoubtedly lead to a misfire. In fact, if your car engine misfires often, it is a sign that the purge valve is damaged.
A defective purge valve and EVAP System causes the accumulation of toxic fumes in the vehicle. In severe cases, this can cause a misfire.
How does a bad purge valve affect my vehicle’s gas mileage?
When your purge valve is not opening correctly or stuck close, it can reduce your gas mileage.
This is because the fuel vapors meant to be combusted in the car are expelled into the environment. Thus, the amount of fuel that should be used by the car is reduced.
How can I tell if my valve is stuck open or closed?
If your purge valve is stuck open and can’t be closed, you might remain unaware for several weeks. This is because it doesn’t register an error code or alert you via the engine light till the valve damages ultimately.
In contrast, a stuck closed purge valve will activate an alert signal immediately. So, you will be aware that there is an issue that you need to fix.
Is a purge valve necessary?
Yes, it is essential to have a purge valve in your car, as it is an important unit of the EVAP system. The EVAP system functions in directing fuel vapors from the fuel tank to a charcoal canister.
When the engine is ignited, this system ensures that the fuel vapors are available to use by the engine. The purge valve is tasked with the function of regulating the volume of the vapors that enter the engine.
An easy and quick way to detect a bad purge valve is with the use of a multimeter. However, sometimes, your car might be malfunctioning, and you are clueless about the situation.
Often, it could be a result of a poor purge valve and EVAP System, but many people overlook that option, even when they notice the signs listed above.
However, having a multimeter can save you a lot of this stress. While you are uncertain of the underlying reason for your car’s poor functionality, you can quickly test the valve and rule out the uncertainty.
Whenever you notice any of the listed signs in your vehicle, don’t hesitate to test your valve. Check if the problem with your car results from a damaged purge valve or another underlying reason.
Driving with a poorly functioning valve can be dangerous and damage your engine and the other parts of your car.