Although modern vehicles have become incredibly complex, the basics of an internal combustion engine remain the same. Any engine still requires three basic elements to run: fuel, compression, and spark. Without these elements, your engine won't produce power and your car won't get you very far. There's a hidden fourth requirement, however, and that's "air." In order for your engine's fuel to actually burn, an appropriate amount of air must be pumped into the combustion chamber. The exact amount required is known as the stoichiometric ratio, and if this requirement isn't met, then the fuel entering your engine will fail to burn completely.
Because of this requirement, proper management of airflow into your engine is vital. Here are just three things that can potentially throw a wrench into the works and keep your engine from burning cleanly and efficiently.
Faulty O2 Sensors
These little guys are the cause of many check engine lights and frustrating for car owners. Depending on your vehicle, you likely have between two and four oxygen sensors. The purpose of the O2 sensor is to monitor how much oxygen is entering your exhaust without being burnt. Your car's computer uses this information to adjust the fuel mixture to maintain the proper stoichiometric combustion ratio. If you have a faulty O2 sensor, it can lead to an imbalance in your air to fuel ratio. This can lead to poor performance and fuel economy.
Bad Mass Airflow Sensor
Yep, it's another sensor problem! Although less likely to trigger a check engine line during its early failure stages, your mass airflow sensor (commonly abbreviated as MAF) can also wreak havoc on your fuel economy and engine performance. Unlike the O2 sensors, your MAF's job is to measure air before it enters your engine. As the name implies, they work by measuring the actual mass of the air that passes through them.
Like O2 sensor data, this information is used by the engine to determine the appropriate amount of fuel to send into the combustion chamber. Unlike an O2 sensor, the symptoms can sometimes be significantly more severe. A MAF that has entirely failed can lead to your car stalling or losing most of its power.
Your engine's vacuum is the air pressure differential created by the engine's intake stroke. During the downward intake stroke, your engine pulls in air from the outside environment, creating a vacuum in the process. This vacuum pressure is used by various components in your car, all of which are connected via flexible vacuum hoses. Leaks can develop in these hoses (as well as various gaskets around your engine bay), leading to a common condition known as a vacuum leak. As the engine moves through its intake stroke, extra air is pulled in through these leaks.
But wait, isn't air a good thing? Keep in mind that your engine needs to maintain a perfect balance of air and fuel. Your mass airflow sensor's job is to measure the amount of air that enters the engine, but vacuum leaks occur after the MAF has already performed this measurement. This means that unmetered air is entering your engine, creating what is usually referred to as a "lean" condition. This means that more air is entering your engine than is necessary, and the result can be anything from poor fuel efficiency to a very noticeable loss of power.
Your car's engine is essentially a very fancy, very expensive air pump. Issues with air flow and air metering can cause major drivability symptoms, so it is important to repair them as soon as you realize that a problem exists. For more information, contact companies like Wilson's Auto World.