Home Diagnosis and TroubleshootingEngine Problems Dirty Air Filter – How To Tell If You Need A New Filter?

Dirty Air Filter – How To Tell If You Need A New Filter?

by Jordan Harris
Dirty Air Filter

Are you experiencing weird symptoms like the engine is down on power and there is a check engine light on the dash? If this is the case, then you might be having a dirty air filter that is causing an obstruction and is ruining the performance of your vehicle.

Having a problem can be really tricky to diagnose especially if you have just purchased the car and don’t know what and when has been replaced on it. And the air filter is one of the most crucial components when it comes to operating the engine. A dirty air filter can cause you a lot of trouble down the line and make you even regret that you purchased the car.

That’s why it is key for you to study and observe your car. You need to note the small bits that are causing this distress to you. As you know, everything is in the little things. And this filter is one of them. With a dirty air filter, you can lose even up to 10hp from your engine which is a big number if you run a smaller displacement engine. The car will be extremely sluggish and slow to react. But how you can tell that the air filter is dirty? Well, we are going to help you out.

First, we are going to learn what is an air filter and why it is so important. Then we will cover the symptoms of a dirty air filter. Later on, we will move on to diagnosing the problem and determining if the filter needs replacing, and also how you can do it. So, if you want to learn more, follow along.

What Is An Air Filter?

Now before we dive into more complex things like the dirty air filter symptoms and how to solve this problem. Let’s first start from the basics and cover what is the air filter in general. Why the car air filter is needed after all? Let’s elaborate.

The air filter also known as air cleaner is a simple air filtration device that is installed in the air box of each internal combustion engine. This filter is often manufactured out of paper or foam in some cases.

This device has a simple role to filtrate the air that is going into the throttle body. The air filter as we said, is installed in the engine’s airbox.

Which is a square-shaped plastic box that is tightened either with clamps or with screws. Then from the airbox, there is a big intake hose that is going to the MAF sensor and then it is connected with the throttle body which regulates how much air to be sucked in.

Overall, this is the work that the air filter has. Nothing that complicated. But replacing this filter is quite essential when it becomes dirty because you will experience dirty air filter symptoms sooner or later.

Later in this article, we will elaborate on all of the possible outcomes when this filter is failing and the symptoms it produces. Now let’s discuss the function of this filter in the following chapter.

Why Is The Air Filter So Important?

So, we learned what is an air filter and what it looks like. Now let’s see why this filter is so important and means a lot for your car. What makes it irreplaceable and if you have a dirty air filter there will be so many possible problems that are going to happen.

The air filter is a heavy-duty device. For each liter of fuel, the engine is burning there should be 2.65kg of pure oxygen. If there is less oxygen the fuel to air mixture will be too rich and you will suffer from the symptoms of a dirty air filter.

If you didn’t know, in order for the engine to get that amount of oxygen it has to suck over 9000 liters of air. This is because in the air that we breathe there is not only oxygen but also other gasses. The oxygen content is only about 20% from the air. So, you can imagine over 9000 liters of air to be sucked by this component. That’s a crazy amount.

And that’s why the air filter is a key component. The air filter is preventing a lot of harmful particles that are found in the air to enter the combustion process and possibly cause some damage to the internals of the engine.

Unfortunately, though, this air filter tends to clog and this is reducing the passage of air into the combustion. When this situation happens, you start to feel the dirty air filter symptoms that are very common on cars that run filters that haven’t been changed for ages.

So, you should know the right interval for replacing your air filter. And what is this specific interval for replacing a dirty air filter? Let’s elaborate in the following chapters.

When The Air Filter Should Be Replaced?

We learned what is the air filter and why it is so essential. Now before we cover the symptoms of a dirty air filter, let’s learn when the air filter should be replaced.

As we mentioned, this component needs to be replaced sooner or later and in fact, this component has a specific interval when it should be changed. So, what is the right interval to replace the air filter?

The right interval greatly depends on the quality of the filter. Most filters that are built from paper are clogging up pretty quickly.

Even though some would say, replace it every 20,000 or 30,000 miles. The best interval is to replace them every 10,000 to 15,000 miles, or once every 2 years. Why this early?

Well, because these filters often tend to fail prematurely as we said. They will clog up and the car will produce dirty air filter symptoms that will be quite annoying to deal with and will make driving your car a lot more difficult.

Some filters that are aftermarket are high quality. They do not require replacement at all. The only thing you will need to do is to wash them when they become dirty. These are usually K&N filters or other similar brands that offer expensive reusable filters.

Other filters that do not require replacement are the cold air intakes. These are also washable and do not have a mileage limitation. In fact, they even have a warranty. So, if you are planning a cold air intake installment, this might be the right thing for you. You will get rid of the dirty air filter and also gain some performance. A boost of 10hp or more is often the case with these intakes. Now, let’s move to the symptoms.

Symptoms Of A Dirty Air Filter

So, we have covered what is the air filter and we learned that is a device that was meant for air filtration and protecting the engine from possible debris deposits that are found in the air. Then we learned the importance of this air filter and why it is so essential when it comes to tackling this problem and the intervals when it should be replaced.

Dirty Air Filter

Now let’s cover the dirty air filter symptoms. As you know, the car always develops symptoms whenever some of the components are not working properly. And so in the case with the air filter. The car will not be happy with this type of work with a dirty air filter and sooner or later will starts to show its downsides. So, which are these symptoms? Let’s elaborate.

1. Check Engine Light

Now let’s cover the first symptom of a dirty air filter. And that is the check engine light. Remember that this symptom doesn’t always happen. But it can if the air filter is so dirty and for more than 30,000 miles has not been replaced. And trust me, there are cases like this even more than you can imagine.

As we mentioned above, the right time to swap your air filter is about 10,000 miles more or less. This is if you go for optimal performance. If you delay this change, the performance might suffer a little bit.

Nevertheless, when it comes to the check engine light, this light will illuminate if there is a problem with the delivery of air. More precisely, the MAF or MAP sensors might alert the ECU that there is not enough oxygen inside of the combustion.

When this happens the ECU will detect the issue and throw some codes concerning these sensors. When these codes appear it’s either that the sensors themselves are broken or dirty, or the air filter is dirty. The best would be to replace the dirty air filter and clean the sensors. If the code persists, then it’s up to the sensors themselves. Now let’s move to the following symptom of a dirty air filter.

2. Engine Misfires

Engine misfires are also another very common symptom of a dirty air filter. But why is this the case, what do the engine misfires have to do with a clogged air filter? Well, they have a lot to do with the misfires.

Whenever there is less air than gasoline this will cause misfires inside of the engine. The engine will not love this type of work and inside of the cylinders misfires will start to happen.

Whenever there is a misfiring engine, you will notice how the engine works pretty much unevenly and this will affect the engine’s overall performance. These noises will usually come from the top of the cylinder so you will be able to find them.

Usually, one or two cylinders happen to misfire. But in this case, pretty much they will all start to misfire and produce weird noises. Also, you can expect the exhaust pops and bangs to happen when this symptom of a dirty air filter occurs. Now, let’s elaborate more on the other symptoms of a dirty air filter.

3. Rich Fuel To Air Mixture

Another symptom that is closely associated with a dirty air filter is the rich air to fuel mixture. But what is rich air to fuel mixture in general?

As we mentioned, the ideal air to fuel ratio should be 14.7:1. This is 1 gram of fuel and 14.7 grams of air. Everything below these numbers is considered a bad fuel to air mixture.

Which in this case is a rich air to fuel mixture. Rich is when there is too much fuel and a small amount of air, and lean air to fuel mixture is when there is too much air and a small part of fuel.

So, what happens is that when there is rich air to fuel mixture is that there is too much fuel and very little air. Attributed by the dirty air filter. So, you can imagine what is happening whenever the fuel to air mixture is too rich and the engine is not happy.

That’s why it is important to diagnose the issue of a dirty air filter soon if you want to avoid some permanent consequences to your engine. But more on that later after we cover all of the symptoms of a dirty air filter.

4. Fouled Spark Plugs

Fouled spark plugs are another very common symptom of a dirty air filter (unless you know how to clean a spark plug and how to clean spark plugs). Why is this the case? Well, this is the case because the car as we mentioned above is running a rich fuel to air mixture.

Meaning that the fuel in the cylinders cannot be fully ignited. Resulting in fouling of the spark plugs. When there is too much gas in the cylinder that the spark plugs cannot ignite because there is little or no oxygen. This gasoline will end up sticking to the spark plugs.

Potentially damaging them and ruining them. So, you need to be aware of this situation whenever there is unburnt fuel in the cylinders. And the rest of the fuel will end up in the exhaust. Which is the next dirty air filter symptom that we are about to cover.

5. Smell Of Gas From The Exhaust

The smell of gas from the exhaust pipe is another common symptom of a dirty air filter. This symptom is a consequence of the rich fuel to air mixture. But why is this the case?

This is the case because the gasoline that is inside of the cylinder is not completely ignited since your dirty air filter isn’t allowing the air to get inside of the combustion and the fuel to be ignited fully. Leaving a lot of the fuel to be dumped in the exhaust valves and then into the exhaust itself.

If you hear detonations at some point in your exhaust you shouldn’t be confused. A lot of cars back in the day when they were carburetted were running rich and explosions or similar bangs in the exhaust were a common thing. They can also happen in fuel-injected cars as well if the dirty air filter is not allowing enough air for the combustion to be successful.

Running your engine like this could also damage your catalytic converter as well as the O2 sensors. So beware of this symptom of a dirty air filter. Now let’s move on to the last of the symptoms.

6. Poor Engine Performance And Poor Fuel Economy

And last, but not least in our list of a dirty air filter is the poor engine performance along with the poor fuel economy.

Whenever there is too little air in the combustion the performance will suffer by a big margin. You might lose up to 30hp because of this problem.

After you replace the filter the car will feel rejuvenated and like brand new. The engine will breathe much better and the input on the gas pedal will improve.

As well as the fuel economy will improve. Usually, the fuel economy will suffer when you are running a dirty air filter. But as you bring it back to factory spec it will return to normal and your wallet will thank you.

So, how do you tell if you have a dirty air filter and this filter needs replacing? Well, that’s what we are going to elaborate on in the following chapters in-depth where we will learn more about this diagnosing and replacing process.

How To Diagnose And Replace A Dirty Air Filter?

We have covered all of the symptoms of a dirty air filter, now let’s see how you can diagnose and replace one of these filters. Knowing this is extra essential if you plan to pull this off at home in a DIY manner. And honestly, it is one of the perfect DIY jobs for any beginner out there who wants to start wrenching and do some work on their car.

So, how to diagnose a dirty air filter? Well, the answer is simple, you will need to remove the cover of the airbox. This cover is usually held by screws or clamps.

Then you have to remove the clamp that is holding the airbox intake hose and then you have clear access to the air filter.

Remove the filter and see its condition. If the filter is all dirty inside instead of light yellow. It means that this filter has seen better days and it is time to replace it with a new unit.

Get a replacement filter and install it in the airbox. Just not forget to clean the airbox first and make sure that there are no contaminants. Then tighten everything up to spec and you are good to go for another 10,000 or 15,000 miles if you like. No more dirty air filter for you and you will never have to worry again in the near future about poor engine performance and bad fuel economy. But how much does it cost to replace a dirty air filter? Well, that’s what we are going to discuss next.

Cost To Replace An Air Filter?

We covered the diagnosing and replacement process of the air filter. Now let’s discuss the cost. How much does this air filter cost to replace?

Well, it’s cheap. Cheap enough to replace it whenever you want. On average, an air filter costs about $30 to $70. Depending on the make and model.

That’s why I recommend replacing it whenever you are doing an oil flush, it is very easy to remember when it was the last time you replaced it and also replacing it sooner has its own benefits like increased engine performance and overall a much healthier engine.

You can also opt to go for an aftermarket air filter that is washable. These usually cost about $100 to $150 but they are bolt-on. Just replace your stock filter with these filters. Aftermarket filters are also good for performance.

Dirty Air Filter

With these filters, you can get about 5hp more in comparison to stock. If you opt for the cold air intake you might even get about 15 to 20hp. Which is quite a lot and these also last forever and you will never have to worry about a dirty air filter and about replacing them. They are fully washable and you can wash them with a hose and all of the dirt and debris will get removed from them.

So, if you want to get some performance of your car. I would recommend going aftermarket. If not, replace your stock air filter every 10,000 to 15,000 miles or when you start feeling the symptoms of a dirty air filter because they will come sooner or later.

Protecting Your Engine: Facts

  1. The air filter is the first line of defense for the engine by preventing dirt, dust, and leaves from entering the engine compartment.
  2. Over time, the engine air filter can become dirty and lose its capacity for filtering the air going into the engine.
  3. A dirty air filter can reduce the amount of clean air that reaches the engine, leading to a lack of acceleration and poor engine performance.
  4. A clogged engine air filter can cause unburned fuel to form a soot residue that accumulates on the spark plug, leading to engine misfires, rough idling, and hard starts.
  5. Strange engine noises, coughing or popping noises, and excessive vibration can be symptoms of a dirty air filter.
  6. A dirty air filter can cause the Check Engine light to come on due to an inadequate supply of air to the engine that results in a buildup of carbon deposits.
  7. Black smoke or flames coming from the tailpipe can be a consequence of a dirty air filter.
  8. A visual inspection is an easy way to know if your air filter needs to be changed.
  9. A drop in fuel economy can be a common sign of a dirty air filter in older carbureted vehicles.
  10. While manufacturers vary on their recommendations on how often to change the air filter, if you notice any of these signs of a dirty air filter, it’s time to have it inspected or changed.

Conclusion To Dirty Air Filter

In this article, we have covered a lot when it comes to the dirty air filter problem. First, we learned what is the air filter and why it is so important to be changed. We also discussed the average replacement interval which is usually about 10,000 to 15,000 miles.

Then we learned all of the dirty air filter symptoms and as we learned, whenever the air filter gets dirty, you will start to experience a drop in fuel efficiency, loss of power. Also, other symptoms might include a check engine light, engine misfires, and fouled spark plugs.

After, we discussed the dirty air filter replacement procedure as well as the cost to replace this component.

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