What Is a Throttle Body?

An engine is like a living breathing thing, and just like humans, it requires plenty of fresh air to run properly. Inside the engine, there’s something called the throttle body tucked into the air intake system. This is a tiny part that plays a big role in how well your engine runs.

So, what does a throttle body do, and why should you care? Let’s dive right in.

What is a throttle body?

A throttle body is a tube-shaped housing that’s part of an engine’s fresh air intake system. Within the housing of the throttle body is a butterfly valve that opens and closes to vary the amount of air that enters the engine.

What does a throttle body do?

The throttle body regulates the amount of air that comes into an engine.

Gasoline engines are also known as internal combustion engines or ICE. Air enters an ICE engine where it is mixed with gasoline and then ignited by a spark plug to create a tiny little explosion (repeated thousands of times a minute) that moves the pistons and provides the power to move the vehicle.

The throttle body has a valve that opens and closes depending on how much throttle (pushing the accelerator down) the driver uses. Pushing down harder on the gas pedal opens the throttle body valve more, allowing more air into the engine and intensifying the ICE process. Push the pedal less, and the throttle body opens less, providing less overall acceleration.

Where is the throttle body?

On older vehicles that run a carburetor, the throttle body is built into the carburetor assembly and operated by a cable connected to the accelerator pedal. Since a carburetor mixes air and fuel before delivering it to the engine for combustion, the more you press the throttle, the more air and fuel will dump into the engine.

Modern fuel-injected vehicles separate the fuel delivery and air intake processes. On these more modern engines, you’ll find the throttle body located between the fresh air filter and intake manifold. Older vehicles are operated with a physical cable that’s connected from the accelerator pedal to the throttle body itself. More modern cars opt for an electronic, drive-by-wire system that’s controlled by the engine control unit (ECU).

Keep in mind some engines have multiple throttle bodies. This is especially true if the engine is a V6 or V8. Some high-performance engines—like BMW’s S54 straight-six, the S65 V8 in the M5, and the S85 V10—all have high-performance, individual throttle bodies on each cylinder.

How do I maintain my throttle body?

Engine air filters are designed to scrub the air of debris and contaminants before entering your engine’s air intake system and are the best way to ensure the throttle body stays clean and functional. If your engine air filter is clogged with debris, it is no longer effectively keeping gunk out of the intake stream. Parts like the throttle body and intake manifold will get dirty and gunky.

Even a perfect air filter maintenance routine may still require DIY’ers to clean the throttle body of any gunk and debris at some point during the vehicle’s life. To properly clean the throttle body, you’ll need to remove it from the air intake system and give it a dousing of commercial throttle body/carburetor cleaner along with a good scrub down with a brush or rag.

If you’re taking on this type of project, pay special attention to the butterfly valve and the area around it.

Common throttle body problems

A well-maintained vehicle will not encounter issues with the throttle body. But some issues can pop up if you’ve been lax on the maintenance or if there’s a defect in the throttle body.

Failed temperature sensor

Modern fuel-injected vehicles use a component known as the intake air temperature sensor to measure the temperature of air coming into the engine’s intake system. The ECU will adjust the fuel/air ratio for the conditions depending on the temperature. If this sensor fails, the wrong air/fuel mixture will be delivered to the engine, and drivers can experience everything from stalling to an illuminated Check Engine Light.

Throttle position sensor

Every electronically operated throttle body has a throttle position sensor that sends the position of the accelerator pedal to the ECU. If the throttle position sensor fails, the ECU may send the wrong data to the engine and close or open the throttle valve at the wrong time. As you can imagine, this can cause major concerns for drivers who can experience everything from stalls to unintended acceleration.

Dirt, debris and buildup

Over time, all matter of gunk will build up in the throttle body, especially if the engine air filter is not regularly changed out. Debris build up on and around the butterfly valve of the throttle body, which can cause it not to open all the way, get stuck open or operate slowly. Everything from uneven acceleration to a rough idle can result from a gunked-up throttle body.

Conclusion

Armed with information on how a throttle body works can be crucial if you’re experiencing issues with driveability on your beloved car. Although this part is relatively simple, it performs a crucial role in your engine by regulating how much air makes it into the engine for combustion. Any malfunction will be immediately noticeable. If you have a car with higher mileage, some proactive maintenance could ensure your vehicle’s throttle body is in peak condition.