So, have you noticed a check engine light warning on your dash? Are you experiencing some rough engine idle after you start the engine? This can be a frustrating situation for you as a driver. But you shouldn’t worry because you are probably driving with bad purge valve.
- What Is An EVAP System?
- How Does EVAP Work?
- How A Purge Valve Works
- How To Test
- Cost To Replace
This valve, although it’s a small component, is crucial for your EVAP system to work properly. Without it, your engine is going to have a hard time working and it will run extremely rich.
This rich fuel to air mixture can also have an impact in the long run on other components in your car. This imbalanced fuel to air mixture is not good. It will soon affect your spark plugs and will start to develop carbon buildup all over your engine.
Your spark plugs are going to fail really quickly and also the whole engine will suffer in the long run. That’s why you shouldn’t be driving with bad purge valve.
By driving a car with a bad purge valve, you are risking some of these harmful particles getting out and escaping if there is a vacuum leak. Some of these systems might also have vacuum leaks that can indicate a bad purge valve. That’s why it is crucial to inspect this issue with a code reader and check the condition of the purge valve.
In this article, we are going to cover everything you need to know when it comes to driving with a bad purge valve. We will learn how the EVAP system works and what are its integral parts. Then we are going to see what are the symptoms of a bad EVAP valve. Also, we will see how you can test a valve using two methods. Lastly, we are going to cover the bad purge valve replacement process and the cost to replace it. So, let’s dive into it.
What Is An EVAP System And How Does It Work?
The EVAP system is crucial when it comes to emissions control. Without this system, we couldn’t be able to control the emissions of our vehicles and they would pollute far more than they are now. Because of the EVAP system, we are driving relatively cleanly. Modern cars still pollute, but thanks to this technology they are far cleaner and more eco-friendly.
The EVAP system removes most of these air pollutants that would otherwise destroy the environment. Just imagine how New York looked before the emission standards from the 70s? There was so much smog that it was even hard to see. But with these new systems, the situation has changed drastically and thanks to that we are breathing a lot cleaner air and also, we improve our health.
Some of the particles that the EVAP system controls are Hydrocarbons. These particles are some of the most harmful particles that spread in urban environments and cause some deadly diseases that thousands of people each year die from.
Another pollutant is carbon monoxide. This carbon monoxide is a product of incomplete combustion and inhaling this carbon monoxide can cause carbon poisoning and which is the inability of the blood to carry oxygen.
Other particles include NOx. NOx particles are formed when the nitrogen that is released in the air reacts along with oxygen inside of the engine. These NOx particles were the primary factor for the appearance of smog and acid rain. Also, it’s extremely poisonous and damaging to the health of individuals.
Some of the other particles include Sulfur Oxide, a particular matter that is released from the burning of the fuel, and volatile organic compounds.
Considering all these harmful particles we can be thankful that we have the EVAP system.
How Does The EVAP System Work?
How the EVAP system works is pretty straightforward. This system is simply collecting all the harmful fumes that are inside the gas tank and creates a perfect seal. It doesn’t allow these particles to escape into the atmosphere.
So, what the EVAP system does is redirect these harmful fumes into something that is called a charcoal canister. This canister purifies these fumes and the charcoal canister then releases these fumes into the engine to burn.
This charcoal canister is filled with materials that trap these harmful particles and do not allow them to travel into the atmosphere. As its name implies, inside of the canister there is activated carbon that works all of the magic in keeping the harmful particles inside of this canister.
Then, from this canister, the less toxic fumes which also contain oxygen goes inside the intake. But before they reach the intake, a special purge valve has to open.
The gases cannot get into the intake immediately because they will cause harm to the engine. There will be basically too much oxygen and air inside of the engine and the engine is going to start running rich.
And when purge valves go bad, they allow this practice, and your intake has an overflow of gases and the combustion of the engine becomes uneven.
This uneven combustion will affect your driving experience and also will worsen your fuel economy. There will be multiple symptoms that you will be facing with and some of them will really annoy you. One example is the check engine light. That’s why driving with bad purge valve is not okay. But we are going to cover that in detail a bit later. Now let’s see where these purge valves are located.
Where Is The Purge Valve Located
For a beginner, finding the purge valve can be extremely tricky because these valves cannot be easily distinguished from other components. That’s with all that complex piping in an engine, especially modern engines. These purge valves can be a pain to locate. But that’s why we are here and we are going to help you out to find your purge valve because we don’t want you to drive with bad purge valve on your car.
The purge valve is usually located on the top of your engine. In the complex piping, you will notice the valve. It is mounted usually on the front side of the engine between the radiator and the engine if you are driving a front-wheel-drive car.
How you can recognize it is by making a close inspection of it. Follow the piping and see where it is plugged into the wiring harness.
The purge valve has to be plugged into a circuit since it works on an electric current to open and close.
On one side there is a vacuum hose and on the other side, the vacuum hose continues. In between is the valve that opens and closes to release the pressure that has been building up inside of the charcoal canister.
Now, since you have located the purge valve, we are going to explain in detail how it works in detail. Then we are going to see the symptoms of a bad purge valve and how you can test it and stop driving with bad purge valve.
How An Evap Purge Valve Works
The EVAP purge valve is an electronic device or better called a solenoid. This solenoid opens and closes when there is a need to.
The purge valve sends its data to the PCM and communicates directly with the PCM of the vehicle. From here, it gets all the instructions to know when to open and when to close.
This is important because the PCM knows everything and is the main piece of equipment that instructs every component to deliver flawless performance.
When this EVAP purge valve tends to fail. It usually gets stuck in either its opened or closed position. If it’s open, you will have too many gases in your combustion chamber.
If it stays closed, it will develop a vacuum leak from all that pressure that is not released. But let’s say that you have a vacuum leak in your engine. You will probably notice that hissing sound when you try to hear how the engine is working. This is a dead giveaway of vacuum leaks.
If the purge valve is stuck open, your engine is going to run extremely rich and will ruin the performance of the whole engine. Also, your fuel economy and your pocket are going to suffer from the frequent visits to the gas station.
Not to forget the implications for your engine. Running the engine like this with rich fuel to air mixture is going to leave some permanent effects on your engine and its overall performance. But more on that in the next chapter when we are going to cover the symptoms when you are having a bad purge valve.
We will share a video here in which a specialist explains how the bad purge valve works and how you can test a bad purge valve by yourself. We are also going to cover the testing phase in this article.
What Are The Symptoms Of A Bad Purge Valve?
Like with every other component on your car. When your purge valve is not working properly or does not work at all, it develops some symptoms. And since it is connected with the PCM, this issue is pretty easy to diagnose. In this chapter, we are going to share all the main symptoms when it comes from a bad purge valve. This way, you don’t have to be driving with a bad purge valve.
1. Check Engine Light
The check engine light is one of the most frequent symptoms of a bad purge valve. As we said, this valve is directly connected with the PCM. And the PCM instantly knows when you have a bad purge valve. It just checks the connection and if the purge valve does not react, the PCM knows that the purge valve is inoperable.
That’s why it shows a check engine light on your dashboard. Check engine lights can be annoying but they are there for a reason. And that reason is to make sure that you don’t end up with a poor-running engine in the end.
When you have a check engine light, the best thing to do is to connect the car to an OBD2 scanner. Then scan the car for codes. If your purge valve is not good, you will get a code. Look for these codes and what they mean. Make sure that the diagnosis is right and if the scan really shows that the purge valve is bad, then you will have to replace this valve with a new one.
Later in this article, we are going to cover the costs to replace a bad valve and how you can perform this work. It’s pretty straightforward and doesn’t require a lot of tools to do it. Plus, it’s an extremely DIY-friendly job. Especially for beginners that are new to the car world.
2. Rough Running After You Fill Up The Car With Gas
If your purge valve is broken and is stuck in an open position, it means that the car will run rich. This means that a lot of fumes go inside the engine and the fuel to air mixture is messed up.
This also can pop a check engine light on the dashboard. The computer knows when the fuel to air mixture is wrong and will show you the check engine light.
Also, with this problem, you will notice how your car runs rough and is extremely unstable at idle. This is most pronounced when you fill up the tank with fresh gas and there is an extremely high density of fumes in the tank and these gases must escape from somewhere.
If the purge valve is bad, they escape and find their way into the engine. This results in your fuel to air mixture is completely messed up and ruining your car’s idle.
3. Vacuum Leaks
Vacuum leaks are another problem when you are driving with a bad purge valve. Especially if the valve is stuck in a closed position.
This stuck valve is going to create a lot of pressure and can crack the vacuum hoses. Bad vacuum hoses will cause the gases to escape into the atmosphere.
If you have a vacuum leak, you are going to notice this symptom by the hissing sound your car makes. If your car engine is hissing at idle, it means that your vacuum is not working and the fumes are escaping inside of the engine bay.
This will worsen your emissions and will make your car pollute more because these gases are instead injected into the combustion chamber and have to be burned off. It will result in them escaping into the atmosphere. That’s why driving with bad purge valve is not recommended.
4. Emission Inspection Fail
Another thing you will notice if you try to register a car with a bad purge valve is that you are going to fail the emission inspection.
Without passing the emission inspection, you are not able to register the vehicle in your state. And the government agency is going to tell you to fix your bad purge valve and bring your car again to pass the inspection.
5. Increased Fuel Consumption
Another consequence of the bad fuel to air mixture that is caused by the malfunctioned purge valve is the increased fuel consumption.
If your car receives more air into the intake along with these fumes, the computer will think that it needs more fuel to dump into the engine. More fuel means more frequent stops at the gas station. This increased fuel consumption will also make your engine build up more carbon and will clog the spark plugs.
Running your engine like this for a long time can ruin the performance of the vehicle. That’s why it is recommended that this valve is replaced as soon as you notice these symptoms.
6. Bad Engine Performance
Bad engine performance is also a consequence of the incorrect fuel to air mixture. This will cause your engine to misfire very frequently and you will think that it’s something else in your ignition system.
That’s why a good check with an OBD diagnostics reader is a must in these situations. And driving with bad purge valve is out of the question.
But how can you test if you are having a bad purge valve? It’s pretty simple and we are going to answer that in the next chapter.
How To Test A Bad Purge Valve Solenoid?
Testing a purge valve solenoid is a good idea if you think that your solenoid is good and something else is causing all these symptoms to appear. You can test the purge valve solenoid in two ways. One is simpler and for the other, you are going to need a vacuum test. If you want to see these tests in practice you can check out the first video we attached.
The Simple Method
The simple method as its name implies is extremely simple. If you think that your solenoid is stuck open, just remove the solenoid from the vehicle and blow into one of the holes.
If the air passes through, the solenoid is open. Or if the air is blocked it means that you have a vacuum and the solenoid is closed. To investigate this issue further, you are going to need a vacuum test.
The Vacuum Tester Method
With this method, you will be 100% positive that your purge valve is broken. To perform this method, you will need to create a vacuum from one side of the valve.
So, for that purpose, you are going to need a vacuum tester. Connect the vacuum tester and build up enough pressure so the purge valve opens.
And for the valve to open you have to connect the power to it. For this, you are going to need 12V power. Connect the plus and minus and the purge valve should instantly open at that amount of pressure if it’s good. If it’s not the valve, it will not open and close.
Purge Valve Replacement
The cost to replace a purge valve is fairly inexpensive. These purge valves can be found for like $20 online or at almost every local parts store in your area, they are readily available.
And driving with bad purge valve when the part is so cheap is out of the question, to be honest. For something that is this cheap, you cannot delay the repair. Make sure that you fix the valve as soon as possible.
Even if you are not mechanically inclined, following a few online tutorials can teach you how to replace a bad purge valve. It’s that easy. You just need to locate it and replace it with the new one. Make sure that you reconnect everything and you are good to go.
Driving With Bad EVAP Purge Valve
If you keep driving like this you risk carbon buildup inside of your engine. If your car keeps running rich, your engine will eventually start to develop a lot of carbon on the cylinders and the heads.
Not to mention the increased fuel economy and the uneven work. If your engine works unevenly, it will create a lot of stress on the internal components. And they will tend to fail sooner than you expected.
Every part in your car has a purpose and so does the purge valve. To have a proper driving car, you have to complete the puzzle and replace it.
Conclusion On Driving With Bad Purge Valve
In this article, we have covered everything you need to know when it comes to the purge valves. We learned how the EVAP system works and where is the valve located in this puzzle and what is its task.
Then we have learned about the common symptoms of a bad purge valve. And how to diagnose that you have a bad purge valve issue and if you are driving with bad purge valve.
Then we covered the testing process and how these valves are tested. Lastly, we discussed the prices and the relative inexpensiveness of this part, and the easy DIY replacement process. So, if you have a bad purge valve. Replace it quickly and don’t keep driving with a bad purge valve.
FAQs On Driving With Bad Purge Valve
If you still have some questions about driving with bad purge valve, our FAQs here might help…
What Is A Purge Valve
The purge valve is a core part of your car’s EVAP (evaporative emissions) system. It’s also known as a (charcoal) canister purge valve. What this purge valve does is simply trap fuel vapors that have evaporated. Thus, it keeps them sealed inside your EVAP unit’s charcoal canister. Otherwise, these vapors could easily escape into the surrounding air, causing mass pollution and health issues for those near your car. The purge valve is actuated by a solenoid. The purge valve opens when your engine is running and has warmed up to operating temperatures. When it opens, those fuel vapors trapped within the charcoal canister are then released into the engine, where it’s combusted.
What Does A Purge Valve Do
Your EVAP system’s purge valve is controlled via a solenoid, which opens and closes the purge valve based on inputs from a variety of sensors. When your engine is off, the purge valve stays off. However, this valve thus opens when your engine is running and is up to its operational temperatures. The purge valve is responsible for sealing escaped fuel vapors (from the fuel tank) within the charcoal canister. Once your engine is running, the ECU would pulse the aforementioned solenoid to open the purge valves. Thus, letting in some of those fuel vapors flow into the engine to be burned.
How To Clean Purge Solenoid Valve
Every so often, the EVAP purge solenoid valves might get stuck in their fully opened or closed state. Rather than replacing it, you could try giving these valves a good cleaning, as that might dislodge any obstructions getting in the way. To begin, grab some carburetor or MAF (mass airflow sensor) cleaner, and remove the valve from your EVAP unit. Then, spray these cleaning solutions into both ends of the purge solenoid valve. Once that’s done, give that valve a good shake, and wait a few minutes. Let the cleaning liquids drain, and re-spray it again if necessary. Let it fully dry, and install it back onto your charcoal canister.
What Happens When A Purge Valve Goes Bad
When the purge valve goes bad, it could no longer properly re-direct trapped fuel vapors from the EVAP charcoal canister into the engine. Generally, it may either circulate too much fuel into the engine or not enough of it. Thus, the symptoms will be immediately apparent, as your car runs much rougher. This would be especially noticeable after a fill-up at your local gas station. Vehicle performance will suffer, as will your fuel economy, as fuel gets dumped into the engine without control. You may notice vacuum leaks, as your car will undoubtedly fail its emissions testing. One of the more common tell-tale signs of a bad purge valve would be a check engine light.
Can Bad Purge Valve Cause Misfire
Another side effect of driving with bad purge valve would be the misfires. Yes, you can notice misfires as a result of a bad purge valve. This is down to the air-to-fuel ratio no longer being in balance. Hence, impacting the combustion process. It’s worth noting that fuel vapors trapped within the EVAP contribute to around 5% to 10% of the fuel burned inside the engine. If the purge valves fail to open properly, it could drastically cut down this amount, causing incomplete combustion. Thus, a misfire will occur.
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