Throttle Body Buyer’s Guide
- The throttle body’s main purpose is to control the airflow in the intake system.
- It contains a pivoting flat or butterfly valve that opens and closes to increase or decrease the amount of air coming into the engine.
- The butterfly valve’s disc pivots open when the driver steps on the gas pedal. As this happens, the throttle position sensor sends signals to the ECU about the gas pedal input.
- Mechanical and electronic are the two types of throttle bodies.
- An illuminated check engine light, lack of engine power, high idling, and limp mode activation are just a few of the signs that your throttle body is in bad shape.
- Dirt buildup inside the valve and electrical issues contribute to throttle body failure.
- Consider compatibility, engine type, and your budget to find the right replacement for your vehicle.
- If you’re in the market for a new throttle body, allot a budget ranging from $50 to $850.
- With the right tools and know-how, you can install the replacement on your own.
Traditional vehicles rely on combustion for the wheels to spin. This combustion happens at the core of the engine, and involves burning fuel. The process involves more than just fuel but air, as well. As far as science is concerned, fire, explosion, and combustion will only happen if there’s oxygen present.
For the engine to combust more efficiently, the air intake system needs to feed it with air. A component responsible for allowing air into the engine is known as the throttle body. What does a throttle body do? Let’s find out.
What Is a Throttle Body?
If you examine your intake system, you’ll see a valve located between the air intake and intake manifold. This component, which main purpose is to control the airflow, is known as the throttle body.
It contains a pivoting flat or butterfly valve that opens and closes to increase or decrease the amount of air coming into the engine. The throttle body is seen in an fuel-injected car and those that use carbureted engines.
On a fuel-injected engine, the throttle body is connected to the gas pedal either mechanically by a cable or electronically by wire. In an electronically fuel-injected car, both the throttle position and air flow sensors communicate with the computer, which, in turn, supplies the optimum amount of fuel to the injectors.
How Does a Throttle Body Work?
The butterfly valve’s disc pivots open when the driver steps on the gas pedal. As this happens, the throttle position sensor sends signals to the engine control unit (ECU) about the gas pedal input.
When the airflow sensor detects more air, it will demand the computer to increase the amount of fuel being injected. Some vehicles feature a large single throttle body, while select bigger displacement engines have one for each cylinder.
Types of Throttle Bodies
Depending on which type of fuel-injection system your vehicle has, you could either have a mechanical or electronic throttle body. Here’s the difference between the two.
Mechanical throttle body
A mechanical throttle body (MTB) is operated via a cable that’s connected to the gas pedal, and is built with high-grade materials to ensure unparalleled operation. However, they are heavier when compared to electronic throttle bodies. The main advantage, however, is that you’ll only face mechanical failures, which are relatively easier to deal with than electrical failures.
Electronic throttle body
Electronic throttle body, ETB for short, is mainly controlled by the engine control module (ECM), which also handles cruise control, mass airflow sensor, and engine speed sensor readings. The ECM combines these data and controls the throttle valve to the desired opening. Electronic throttle controls have few moving parts compared to MTBs, which means less maintenance cost.
Bad Throttle Body Symptoms
A clean throttle body is important since it’s the component that controls the amount of air needed for efficient combustion. If your throttle body begins to fail, engine performance will suffer. To help you prevent further intake system failure, here are a few common symptoms of a faulty throttle body.
Illuminated check engine light
One of the few early signs you might encounter if you’re having a failing throttle body is an illuminated check engine light on the instrument panel. A car’s electronic throttle control (ETC) module constantly checks the performance of the throttle body. If it detects any issues in the throttle body, the ETC will turn on the Check Engine Light warning on.
Lack of engine power and poor engine response
The engine needs the right fuel-air mixture to attain optimum power. If the throttle body is malfunctioning, it won’t be able to control the amount of air entering the combustion chambers. A slight change in ratio could heavily affect the combustion process. This could result to poor engine performance, as it wouldn’t be able to produce enough power.
Engine shakes a lot when idling
One symptom of a bad throttle body is poor idling. If your car behaves roughly on idle, chances are your throttle body isn’t in good shape. Worse is that your car may occasionally stall due to lack of air entering the chambers.
Car runs on Limp Mode
Have you ever heard of limp mode? Limp mode is a car engine and transmissions’ security feature. It is activated when the engine and transmission control unit detects a serious problem involving the transmission and the engine. When your car is in limp mode, there will be reduced power, as well as decreased RPM. This way, you can drive your car to the workshop safely and without introducing more problems to your engine.
The symptoms, however, are not limited to the things mentioned above. Other signs include hesitation when accelerating, inconsistent surges in speed on the highway, gear shifting difficulties, and a surprising drop in fuel economy.
Be sure to contact a certified mechanic as soon as you experience one or two of these symptoms, as more serious underlying issues could be present in your system. To avoid more problematic issues in the future, it’s best to replace your failing throttle body as soon as possible.
What Causes Your Throttle Body to Fail?
A failing throttle body could be caused by a mechanical or electrical problem depending on what type of intake system your car has. The most common to modern vehicles are electrical and contaminant issues inside the throttle body itself.
Dirt buildup inside the valve
Dirt, grime, and any harmful deposits inside the valve can clog and prevent air from entering the valve’s opening. It will cause an imbalance in the air-fuel ratio by blocking or interrupting the airflow.
Any problems associated with the electrical parts of the intake system can cause changes in the throttle body’s performance. Issues ranging from connectivity to interrupted relay of information being sent or received by the car’s computer and sensors. If there’s inaccuracy in the data, you’ll face jumpy or poor engine performance.
Importance of Replacing a Failing Throttle Body
The first thing you are saving when you replace your throttle body is the air intake system of your car. If the intake system functions properly, you will be able to preserve your engine performance by ensuring proper fuel-air ratio all the time. If your engine is in top condition, your car will run smoothly.
Another benefit of replacing a bad throttle body is power in its most optimal form. A failing throttle body can result in reduced power, as the engine isn’t breathing the right amount of air to combust more efficiently.
Choosing the Right Throttle Body for Your Vehicle
Maintaining the appropriate air-fuel ratio of your car's engine is the throttle body's job. When it breaks or gets damaged, your vehicle could malfunction due to the imbalance in the air-fuel ratio in the engine's combustion system. Consider the following factors when looking for a throttle body replacement:
Determine your car's make, model, name, and year. It greatly helps to know what your vehicle specifications are, since these will be your bases when testing any part's compatibility with your car. You can retrieve your vehicle's information from documents like the owner's manual or registration papers. Another way to find your car info is through your vehicle identification number (VIN).
The throttle body is an engine component, which means that it's essential to identify your engine type when choosing a new throttle body. Looking for alternatives is made easy since automakers frequently manufacture the same engine for different models; and sometimes, even different brands. A Toyota and GM model, for example, could have identical engines, with the throttle body being the exact same part. The difference could be in the prices where one typically is cheaper than the other.
Getting a throttle body for your car depends on your allotted budget as well. Different manufacturers offer different prices for their throttle bodies. Research and compare your options before settling on a body throttle replacement.
How Much Is a Throttle Body?
If you’re in the market for an OE replacement throttle body, allot a budget ranging from $50 to $850. Price varies depending on the brand, type of assembly, product fitting, condition, and quantity sold.
Throttle bodies are sold individually, as an assembly, or as part of a kit. To get the best-quality OE throttle body replacement parts from reputable manufacturers, shop on CarParts.com.
Getting the Throttle Body in Place
For your car to have a proper intake of air, a good throttle body must be installed properly. The throttle body is the one that controls the amount of air entering your engine's combustion chamber. To help you out, here are the steps on getting the throttle body properly in place:
Required skill level: Intermediate
Required tools and materials:
- 0.25-inch sockets
- 0.25-inch ratchet
- Wrench set
- Screwdriver set
Removing the hat
The first thing to go would be the throttle body hat (or simply, the hood). If your vehicle has an aftermarket air intake installed, it would be easier for you. If not, you would just need to remove the flex hose first before the throttle hat.
Disconnecting the throttle
After removing the hood, you would see three electronic connections attached to the throttle body: one in the rear and two on the driver side. To remove the two on the side, simply push down on the tab and pull them off. For the other one, you would need to slightly lift the tab to be able to take it off. Next, remove the vacuum line found in front of the throttle body.
After getting the electric connections out, it's time to focus on the throttle cables. There are also three throttle cables in the assembly - all of which have a C-shaped end connecting them to the throttle. Do not pry them off. To remove them, you need push out the cables toward the opposite direction it is being pushed in. Remember to push the cables past the stud to get it out.
Removing the body
You need to remove the bolts holding the throttle cable attachment brace to the body (there are two in front and one behind the spring on the side). The brace is still attached to the cables so do not move it very far.
Now, you need to remove the four bolts on top of the throttle body. After taking them off, you should be able to lift the body off. Remember to cover the opening after removing the body to make sure that nothing falls in it.
Installing the throttle body
Remove all the sensors (the idle motor, the throttle position sensor, and the MAP sensor) from the old throttle body and install them on the new part. You can now place the new body in place, replacing all the bolts you removed before.
After putting back all the bolts and cables, you would just need to disconnect the negative side of the battery for about 10 to 20 seconds. Reconnecting it after allows the computer to reset and learn the setting with the new air flow rates.
How to Clean Your Car's Throttle Body
A combustion engine system requires a balanced air-fuel ratio in order to function properly. Your vehicle's engine gets the appropriate amount of air, especially upon acceleration, with the help of a part called the throttle. If the throttle body, an integral throttle component, gets dirt and residue inside, the engine's air-fuel ratio will suffer. Cleaning the throttle body, therefore, is important in car care and engine maintenance.
Here's a step by step instruction on how to clean the throttle body:
Difficulty level: Moderate
Tools to be used:
- Car's repair manual
- Ratchet and socket
- Toothbrush or any small cleaning brush
- Throttle body cleaner
- Paper towel or clean cloth
Step 1: Park your car in a level surface and turn the engine off. Allow the engine to cool completely before starting the repair.
Step 2: Open the hood and disengage your vehicle's negative battery terminal. Refer to your car's repair manual to release the fuel system pressure and find other parts unfamiliar to you.
Step 3: Detach the air cleaner assembly. Locate and label any small hoses that you need to remove in order to reach the throttle body. You can use either masking tapes or other specialized labeling tools.
Step 4: Unplug the cables connected to the throttle lever and remove the electrical connectors from sensors, valves, and idle control motor unit. Remove the vacuum hoses connected to the throttle body as well.
Step 5: Disengage the inlet and return fuel lines from the throttle body. Then, unbolt the throttle body unit with a wrench or ratchet and socket.
Step 6: Take off the throttle body from the intake manifold and detach any plastic, rubber, and other electrical components still connected to it. Submerge it in a throttle body cleaner based on the product manufacturer instructions.
Step 7: Change any other damaged parts as necessary and reassemble the throttle body. Get a scraper, lacquer thinner, and a clean piece of cloth, and clean the intake manifold mating surface thoroughly.
Step 8: Place the throttle body unit on the cleansed intake manifold using a base plate gasket and secure the mounting bolts according to the sequence in your car's repair manual. Follow the sequence carefully as it may cause further damage if not replaced correctly.
Step 9: Connect the inlet and reattach the fuel lines, electrical connectors, vacuum hoses, throttle lever cables, and air cleaner assembly. Reconnect the black, negative cable to the battery terminal.