Engine Air Intake System and Components

Engine Air Intake System

The engine air intake system is a system found in a vehicle or motorized device that regulates the intake of air to the engine and is designed to improve engine performance. This system controls the airflow needed for the fuel inside the engine to combust.

The engine air intake system increases engine efficiency, reducing fuel consumption and increasing engine power output. It also works together with the exhaust emission systems designed to reduce engine emissions.

Components of the Engine Air Intake System

The engine air intake system consists of components such as the air filter, intake manifold, throttle body, and intake valves.

Air Filter

The air filter cleans the air entering the engine. It is your first line of defense against debris being drawn into your engine.

Most filters are disposable, but some can be cleaned and reused. The shape, size, and design of air filters vary greatly by manufacturer.

Throttle Position Sensor

The throttle position sensor tells your computer how far open the throttle plate is and how much air is entering the engine.

Throttle Body

The throttle body controls airflow and adjusts the amount of air needed to increase engine performance. When you press the accelerator pedal, the throttle body opens. It has a large plate inside a tube that allows air into your engine. When you press the pedal, the throttle plate rotates to a horizontal position, allowing air into your engine.

EGR Valve

Also called the exhaust gas recirculation valve. The EGR valve
sends exhaust gases back to the engine to be burned again. This helps reduce engine emissions.

Mass Air Flow (MAF) Sensor

This sensor tells the computer how much air is entering the engine.
Air density can vary depending on altitude, climate, and whether your vehicle uses a supercharger or another device to force air into the engine.

Idle Air Control (IAC) Valve:

When the throttle plate is closed, this valve allows a small amount of air to pass around the throttle plate so the engine doesn’t stall.

PCV VALVE

Stands for positive crankcase ventilation. This one-way valve is another device designed to reduce emissions. As fuel and oil vapors accumulate in the engine, they build up pressure in the crankcase. The PCV valve opens to allow these vapors to escape the engine crankcase and injects them into the intake manifold to be burned, reducing pressure buildup.

Intake System

The intake system consists of all the plumbing before and after the throttle body. It includes the tubes between the air filter and the throttle body, and the intake manifold, which distributes air to the individual cylinders separately. Intake manifolds usually have separate tubes called runners leading to each cylinder. This helps the air move faster and allows more air to enter the cylinder.

Air Sensors and Monitors

Your computer uses information from various sensors to determine how much fuel to add to the engine. Your mechanic may refer to the following sensors when discussing your intake system.

Barometric Air Pressure (BAP) sensor: This measures air density like the MAF sensor, but only measures barometric pressure. Air at sea level is denser than at high altitudes, and this sensor is used by some systems to tell the computer how dense the air entering the engine is.
Intake Air Temperature (IAT) sensor: This measures the temperature of the air. Cold air will be denser than warm air, and while cold air requires more fuel, warmer air requires less fuel but can cause the fuel to ignite too early (this is called pre-ignition).
Electronic Throttle Control (ETC) motor: In vehicles with an electronically controlled accelerator pedal (drive-by-wire), this motor is used to move the throttle plate instead of a cable.

Air Filter Replacement

The engine air filter is typically replaced every 15,000-20,000 km; a dirty filter increases fuel consumption.

MAF Sensor

The mass air flow (MAF) sensor measures the amount of air entering the engine, allowing the ECU to calculate the correct fuel-air ratio.

Turbo Engine Air Path

In turbocharged engines, intake air is cooled by passing through an intercooler, which improves combustion efficiency.