Throttle Body: What Is It, How It Works, And How To Clean It

Throttle Body: What Is It, How It Works, And How To Clean It

Unlike fully electric vehicles, gas-powered cars have far more moving parts that require more upkeep as the car ages. Any number of parts can affect the performance of your vehicle, and the throttle body is one of them. If your throttle body is dirty, misadjusted, or malfunctioning, your engine can experience severe issues. There are several different types of throttle bodies; although they vary in design and appearance, they serve the same function, which is regulating the amount of air entering the engine. In this article, we’ll cover throttle body function, common throttle body issues, how to clean it, and how much they cost to repair.

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A throttle body is an electronically or mechanically controlled butterfly valve that controls the amount of air entering the engine, based on inputs from the accelerator pedal. Throttle bodies were first used on throttle body injection fuel systems. These systems mounted fuel injectors onto the throttle body. As the accelerator pedal was pushed, the fuel injectors would spray into the throttle. Later, the throttle body design changed to be used with multi-port and direct fuel injection systems.

But how does a throttle body actually work? It’s quite simple. The throttle body butterfly valve is opened when the accelerator pedal is depressed. This allows more air to enter the engine, increasing RPM and power.

No matter the design, the throttle body location is typically the same: It’s mounted on the intake manifold or plenum and the air intake. When the throttle body opens, it allows more air to enter the engine. The air is then divided and directed towards the cylinders by the intake manifold.

Throttle bodies are known to have their issues and faults. Whether it’s electronic or mechanical, faulty throttle bodies cause the same problematic symptoms. The following are the most common symptoms experienced with a faulty, worn, or dirty throttle body:

Mechanical throttle bodies are fairly simple designs but can still fail. Electronic throttle bodies are more expensive, as they include motors and sensors. These can fail in several ways. The following are the most commonly reported throttle body problems:

A dirty throttle body is the most common throttle body fault. This can easily prevent a car throttle from operating properly. In most cases, cleaning a throttle body is something a DIYer can handle. There are two ways to clean the throttle body:

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Depending on how dirty the throttle body is, removing it may be the better option. In most cases, cleaning the throttle on the vehicle will be sufficient.

The following tools and supplies will be needed to clean a throttle body:

Begin by removing the air intake assembly and gaining access to the throttle body. Have a helper depress the accelerator pedal to open the throttle or gently press it open by hand.

Spray the throttle body cleaner into the throttle body. Use the soft-bristled brush to gently scrub the deposits from the throttle assembly. Spray the cleaner and wipe with a towel. Repeat the process until the throttle body is clean.

Removing the throttle body allows for a more efficient cleaning. You will need a throttle body gasket, and you’ll have to adjust the throttle linkage (if mechanical) and bleed the cooling system on most vehicles. The cleaning process is the same.

On mechanically operated throttle bodies, the cable and/or Throttle Position Sensor (TPS) may need to be adjusted. TPS adjustment is typically done with a scan tool or multimeter.

To adjust the throttle cable, find the ‘collapsible’ section of the cable, loosen the lock nut, and turn the threaded portion of the cable. There needs to be some free play in the cable. If the cable is too tight, the throttle will remain open and result in a high idle. If the cable is too loose, full throttle cannot be achieved, reducing power and acceleration.

Electronic throttles have two internal position sensors and two internal motors. If these throttle bodies fail, the assembly must be replaced. The motors are intricately timed and any attempt at replacement risks improper alignment and operation.

To replace the throttle body, follow these steps:

Most electronic throttle assemblies will need to have the Powertrain Control Module (PCM) relearn the throttle. This may require a set idling/driving cycle or the use of a bidirectional scan tool.

The throttle body will vary in design from engine to engine, which will affect its repair cost. Typically, a cleaning service will cost about $120 – $180, whereas replacing the throttle body will have a wider price range. Typically, a mechanical throttle body will be cheaper than the newer electrical designs. For all vehicles, RepairPal estimates an average cost of between $500 and $640 to replace a throttle body. The price also varies from vehicle to vehicle, as indicated in the table below, which includes popular models like the Ford F-150 and Toyota RAV4:

Throttle bodies serve a vital importance to an engine. Power, fuel economy, traction control, emissions, and even transmission operation depend on a properly functioning throttle. We recommend having throttle bodies cleaned with at least every tune-up service.