What Is a Throttle Body? | How to Clean a Throttle Body?

The throttle body plays a vital role in regulating the amount of air that goes into your engine. When it goes bad, your car may not even start. It’s important to identify a bad throttle body quickly so you can have it fixed as soon as possible.

What Is a Throttle Body?

Throttle body is a component that varies the amount of air entering an engine, by using a flat valve (butterfly) that rotates inside a tube-shaped housing.

In an electronically fuel-injected car, a throttle position sensor and air-flow sensor communicate with the main electronic control unit (ECU), which supplies the corresponding amount of fuel needed at the injectors.

Where is the throttle body located?

On older carbureted engines, the throttle body is built into the carburetor. It is opened and closed through a cable and linkage from the gas pedal and engine vacuum, more fuel is delivered as the valve opens.

On a fuel-injected engine it is normally located between the air filter and the intake manifold, and is connected to the gas pedal mechanically with a cable, or electronically by wire. When the driver presses the pedal the butterfly in the throttle body pivots to let more air flow into the manifold.

When that happens, the throttle position sensor reports to the ECU that you have stepped on the gas. And the airflow sensor detects more air and sends a message to the car’s computer to boost the amount of fuel being supplied by the injectors.

How Does a Throttle Body Work?

The throttle body is responsible for controlling the amount of air that enters the engine.  Here’s how it works:

• The throttle body is connected to the accelerator pedal by a mechanical linkage in older vehicles or electronically in modern vehicles with drive-by-wire systems. When you press the accelerator pedal, it opens the throttle plate (also known as the butterfly valve) inside the throttle body, allowing more air to enter the engine.
• The throttle position sensor (TPS) is an integral part of the throttle body, monitoring the angle of the throttle plate. As the accelerator pedal is pressed or released, the TPS sends an electrical signal to the engine control module (ECM) indicating the current throttle plate position.
• The engine control module (ECM) is responsible for managing various engine functions, including fuel injection, ignition timing, and air intake. Based on the input from the throttle position sensor, the ECM calculates the appropriate amount of fuel required to mix with the incoming air. This ensures proper combustion so you get the desired engine power and performance.
• As the throttle plate opens, more air flows into the engine through the intake manifold. The ECM adjusts the fuel injectors to deliver the correct amount of fuel, creating an ideal air-fuel mixture for combustion. When the accelerator pedal is released, the throttle plate closes, reducing airflow and fuel delivery.

How Many Throttle Bodies?

Most autos have just one large throttle body, but some cars with larger V6, V8 or V12 engines can have one for each bank of cylinders, or even one on every cylinder, although these are relatively uncommon.

Some systems use a throttle body with two smaller throats and butterflies instead of one large one, notably the early Ford truck EFI motors, but the function is the same.

A good air filter is essential to the operation of the throttle body, because dirt build-up can gum up the butterfly, causing a rough idle and drivability issues. Depending on how the PCV breather is plumbed on your car’s motor, you may also get a buildup of oil residue.

How to Clean a Throttle Body?

#1. Disconnect the negative battery terminal.

For safety reasons, disconnect the negative battery terminal before working on the throttle body. It’s a good idea anytime you’re working on any system under the hood since parts like the cooling fan can activate unexpectedly.

#2. Remove the air intake duct and hoses.

Using a screwdriver or socket wrench, remove the air intake duct and any hoses connected to the throttle body. Keep track of any clamps, bolts, or screws for reassembly later.

#3. Disconnect any electrical connections.

Gently disconnect any electrical connections, such as the throttle position sensor or mass airflow sensor, from the throttle body. Be careful not to damage the wiring or connectors.

#4. Remove the throttle body if necessary.

In some cases, it may be easier to clean the throttle body if it is removed from the vehicle. If you decide to pull it off, use a socket wrench to remove the bolts securing the throttle body to the intake manifold.

Keep track of the bolts, gaskets, and any other components for reassembly.

#5. Clean the throttle body.

Wearing gloves and safety glasses, spray the throttle body cleaner onto the throttle plate, inside the throttle body, and around the edges of the throttle plate.

Use a soft-bristle brush or toothbrush to gently scrub away dirt, grime, and carbon deposits. Be careful not to scratch the surface or force the brush into small openings.

Use shop towels or clean rags to wipe away the loosened dirt, grime, and cleaning residue from the throttle body and surrounding areas. Ensure all surfaces are clean and dry before reassembly.

#6. Reassemble.

Carefully reattach any electrical connections, hoses, and air intake ducts removed earlier. If you removed the throttle body, reinstall it with the appropriate gaskets and bolts, following the torque specifications outlined in your vehicle’s service manual.

Reconnect the negative battery terminal to restore power to the vehicle.

#7. Test the vehicle.

Start the engine and let it idle for a few minutes to ensure proper operation. Test the throttle response by gently revving the engine while in park or neutral for cars with automatic transmissions, or with the clutch disengaged if you have a manual transmission.

Bad Throttle Body Symptoms

The symptoms are as follows,

#1. Lack of Power.

When the throttle body is not working correctly, there is either more or less air entering into the mixture which results in a lack of power and the car is not accelerating as it should.

When you press the accelerator, it should ideally allow more air to burn the excess fuel coming in, but if it is malfunctioning there won’t be enough air and because of this, there will be no surge in power.

#2. Issues while accelerating.

Since there is a lack of power, the acceleration of the car will definitely have issues. The car will either have uneven acceleration or it won’t accelerate after a certain point, and both cause issues not only to the power and mileage but also to the longevity of the engine.

#3. Higher or Lower Idling.

When the throttle body is not operating effectively, one of the tell-tale signs is poor or low idling. This includes the engine stalling after coming to a stop, a very low idle after starting, or stalling when the accelerator pedal is pressed down rapidly.

The Dirt collected causes airflow into the system to be turbulent and leads to a fluctuating idle speed.

#4. Dirt or Grime Build-up.

One of the main issues why the throttle body will get clogged is due to the accumulation of dirt and grime within the part, which is also known as coking.

This creates a rough surface, that disturbs the air-fuel flow and diminishes the effectiveness of your engine. Carbon deposits cause a similar problem by generating an uneven surface inside the part.

#5. Poor Mileage.

The fuel economy of a car will get severely impacted by a choking throttle body. The ideal way of measuring the mileage is the full tank-to-full tank method.

You first put a full tank of fuel, make a note of the odometer readings or set one of the trip meters to zero and then travel a few hundred kilometers.

Fill the tank again and make a note of the total amount of fuel consumed. The distance divided by the amount of fuel consumed will give you a clear idea of your car’s mileage. If there is a variation of more than 15%, then there is a high chance that the throttle body has issues.

#6. Electrical Problems.

With cars becoming more dependent on sensors and electronics these days, electronic wiring acts as a nervous system. If the throttle body’s electronic sensor is covered in dirt, this will result in unnecessary corrections to the air-fuel mixture.

This could put the car into a secondary power reduced mode until it gets seen by a service mechanic. For some cars which do not have this mode, there are methods like reducing power, limiting the engine rpm, etc.

#7. Check the Engine Light.

If there is an issue with the throttle body’s performance, it will alert the electronic throttle control. This in turn illuminates the check engine light. Now there are numerous reasons why this warning lights up and a failing throttle body is only one among them.

Hence it would be better if you do some manual check to see if there is dirt building up around the part.

When you consider these individual symptoms, there are a lot of reasons why they could occur. But when some or all of them occur at the same time, then it most probably would be the issue with a failing throttle body and will definitely require your immediate attention.

When Should I Replace the Throttle Body?

If your vehicle is experiencing any of the following symptoms, it could be time to consider having your throttle body replaced:

• Check engine light is on. This light illuminates whenever your engine is experiencing a problem. However, your throttle body is at fault if the issue was resolved and the light doesn’t go off.
• Changing gears or accelerating causes shaking or jerking. A misadjusted idle speed can cause inaccurate combustion causing rough idling and loss of power, and this can be easily fixed DIY-style.
• Misfires and loss of power after repairs. If this happens after you’ve had some work done on the car before, such as spark plugs, check your air filter first. And, if nothing helps, know it’s your throttle body, and you should get to an auto shop.
• Bad fuel economy. If you experience worsened fuel economy or your fuel consumption has changed, your throttle body can easily be the cause.
• Poor engine performance. If your car feels sluggish or like it’s losing power, this could be due to a faulty throttle body.

Average Costs For A Throttle Body Replacement

The average cost of a throttle body replacement can run anywhere from $70 to $1,000. It all boils down to a couple of factors:

• Part cost. The price you’ll pay for the part will combine the manufacturer’s suggested retail price (MSRP) and its wholesale price to repair shops.
• Labor costs. These are what your repair shop charges per hour for the labor associated with installing the new throttle body in your vehicle, including any miscellaneous parts that need replacing.
• Diagnostic fees. If your car shows signs of needing repairs before you’ve got it in for maintenance or service work, it will require some diagnostics to determine what is wrong with it, and those can get pricey fast.

Before tackling the throttle body problem, ensure you’ve ruled out all possible causes. When all else fails, then you can replace the throttle body. It may even be possible to purchase a used throttle body instead of a new one, even though that’s not recommended.

It is important to note that the prices can vary significantly depending on where you live, so be sure to get multiple estimates before deciding which mechanic you want to hire for the repair job.

FAQs.