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What is your car's throttle body (and what does it do)

What is your car's throttle body (and what does it do)

A throttle body is only fitted to petrol (gasoline) cars and comprises a valve that is used to control the amount of air entering an engine, and therefore the amount of fuel admitted from the carburettor or by the injectors.

On a fuel-injected engine the throttle body is normally located between the air filter and the intake manifold, and is connected via a cable to the throttle pedal, or gas pedal, inside the car.

When the driver presses the pedal a butterfly valve moves to let more air flow into the manifold.

The airflow sensor detects more air and sends a message to the car’s ECU to boost the amount of fuel being supplied by the injectors.

On older-style engines, the throttle is part of the carburettor, and is positioned below the venturi, where fuel is mixed with air.

What is your car's throttle body (and what does it do)

Most autos have just one throttle but larger-engined cars can have one for every cylinder - they sit above each cylinder - although these are relatively uncommon.

A healthy air filter is absolutely critical to the operation of the throttle body, because dirty air can cause a build up of pollutants on its inner surface, which over time will interrupt the air flow.

After disassembling it, clean the throttle body with a suitable solvent or carb cleaner, paying particular attention to the throttle plate, using a toothbrush, pipe clear and cotton cloth.

Other throttle body problems include faulty speed/distance or MAP sensors, which send signals to the ECU and cause the engine to stall when the car comes to a standstill or an erratic idle.

An engine that revs too high at idle can be caused by an incorrectly adjusted throttle stop or a vaccum leak in the hoses that connect to the throttle body.