Air Intake System: Importance and Issues

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What is an air intake system and why is it important?

An internal combustion engine (the same one you have in your car) relies on combustion of fuel inside its walls to ensure it can generate power. An important part of the entire combustion process is the introduction of air. Simple science (opposite of rocket science) states that in order to have a fire, you need fuel, air and a spark to light them both up. But an enclosed unit like the engine has no room to let air in. Then how is the combustion process taking place? The answer lies in one critical system – the air intake system.

The basic purpose of an air intake system is to let clear air inside the engine’s cylinders to help ignite the fuel and allow the engine to produce power. There are various types of air intake systems used for different purposes. Here, we are going to talk about the simple air intake system you get in the car you own.

The air intake system allows for clean and continuous flow of air into the engine. While continuous flow is not a major problem for a car’s engine, it is the problem of clean air that poses an issue. To achieve this, an integral part of air intake system is an air filter. There is then a Mass Airflow Sensor that senses the amount of air entering the engine. Its need arises from the utility of the engine and the amount of power it needs to generate. Letting in more air would mean running an air-fuel mixture that is imbalanced in the favour of air (engine runs leaner). This would send your engine’s ECU into a tizzy, making it use more fuel to utilize the excess air. You can put the rest of the equation together. The Mass Airflow Sensor is usually mounted on another important component called Throttle Body. The Throttle Body lets air inside the engine after Mass Airflow Sensor has finished its scrutiny.

What other types of intake system exist out there?

Just like any other system in your car, the intake system also is of different types. Moreover, they are designed and made to fulfil certain purposes and are not suitable for daily driving unless you can live with their drawbacks. So, here are some common types of air intake system:

  • Regular – This is not a type but rather a way to tell you that this is a system you can find on almost any and every road-going vehicle. In this case, the airbox, which contains the air filter, is placed at a spot from where the access to air is unrestricted. This allows ambient air to enter your car’s engine to help ignite the fuel. The modifications made to such a system are minimal and limited to the air filter’s size and capacity. The limitation to such modifications is that not a substantial increase in engine’s power can be felt as the air filter’s size is limited by the size of the airbox in which it is placed. If a high volume air filter is used which fits the airbox, the engine will run richer than usual but not so much as to hurt your car’s fuel economy. This is the basic form of modification tried by enthusiasts on their vehicle’s air intake system.
  • Cold Air Intake – This type of air intake system relies on drawing cool air from the atmosphere to help the engine deliver more power. It requires extra plumbing as the the air inlet will have to be placed as much away from engine’s heat as possible and the inlet is mounted usually on the front bumper of the car. Additionally, a high flow air filter is used to enable more cold air to enter the engine faster. It is used on sports cars and performance-oriented vehicles.
  • Ram Air Intake – This type of air intake system is placed higher than cold air intake system. The reason for that is simple – letting cold air flow inside the system is great but if it is pressurized too, the effects it would have on engine’s power delivery would be significant. To achieve such an effect, its installation is accompanied by installation of an air collector cone to let in more air inside the engine. This dramatically increases the power output of your engine but requires re-tuning of the motor and reduction in fuel economy is a by-product.

What do you mean by engine running lean/rich?

Every engine has certain parameters to adhere to when it comes to combustion. These parameters are directly related to how much power the engine generates, how broadly the power is spread as engine attains higher speeds, fuel economy, etc. These parameters not just affect all these factors but also play a direct role in the longevity of the engine and hence, the use of components in the engine.

An engine has to adhere to a certain air-fuel ratio. The number of parts of air mixed with one part of fuel is what defines air-fuel ratio. For a petrol engine, the ideal air-fuel ratio is 14.7:1 or 14.7 parts of air to 1 part of fuel. This means that to burn one part of fuel efficiently and effectively, 14.7 parts of air need to be present.

Let us say that due to some reason (modification perhaps), the engine is getting more air than it needs to burn fuel efficiently. Let us say the air-fuel mixture hits 20:1 (more air than needed) mark. In such a case, the pressure inside the cylinder increases, increasing the chances of engine knock and catastrophic engine damage. On the other hand, if the air-fuel ratio hits 12:1 (less air than needed), the engine will run richer. This usually allows for more power generation inside the car’s engine and pressure inside the cylinder will decrease. However, your car will consume more fuel. Before fuel-injected engines became widespread, may people used to run their car’s engines rich by tweaking the carburetor when travelling in mountainous regions (lack of air substituted by more fuel). Fuel-injection systems are capable enough to deal with such changes as they come equipped with ECUs that balance such parameters on the fly.

What all can go wrong with my engine’s air intake system?

Since there are not much components to deal with, there are few issues that plague your car’s air intake system. Some are easy to diagnose and fix while some may require more elaborate repairs and/or replacements. Here are some of the major issues you will face if air intake system starts malfunctioning:

  1. Clogged air filter
  2. Malfunctioning mass airflow sensor
  3. Clogged throttle bodies

Apart from these, there are issues that can also plague your system but that is because on of these components would have stopped working as such.

What are the symptoms of a faulty air intake system?

A faulty air intake system can cause various issues and throws out various signs for you to understand if there is anything wrong or not. Here are some of those signs:

    1. Low fuel economy (Can be caused by a recent modification or malfunctioning Mass Airflow Sensor)
    2. Engine knocking (Malfunctioning Mass Airflow Sensor lets more air to enter the engine)
    3. Car unable to run in mountains (air pressure issues)
    4. Stalling (engine not getting enough air to start the combustion process)

What can I do in such a case?

There are a few things you can do in such a case. But your work is something that can be classified in the proactive category. Every routine service you take your car for in the workshop entails cleaning up of air filter and replacement too, if needed. Understanding the condition of the air filter will tell you a lot about what is happening inside our engine. Since technology has advanced at a rapid pace, the chances of Mass Airflow Sensor going bad have come down significantly. Consequently, throttle bodies also are more or less able to sustain a lot of abuse before needing repairs and/or change. If the Mass Airflow Sensor and/or Throttle Bodies needs repair and/or change, be sure that there might be more things going wrong inside the engine than you know. The most basic thing you can do is replace the air filter. However, stick to your car’s owner’s manual for locating the air filter and replacing it with the same kind of unit as was already in place before it went bad. If that does not fix your issue, take your car in for a check-up at the workshop.

Conclusion

Since there are few parts in the engine air intake system, it is bound to go bad only when it is not routinely checked. For that, routine servicing of your car is necessary. For that we, at CarDekho, are ready to help you with. All we ask you to do is log on to services.cardekho.com and schedule a service.