Throttle valves

The throttle valve, or also called control valve, is located in a tube on the intake manifold of the engine between the air filter and the intake manifold and is only installed in gasoline vehicles.It regulates how much air the engine sucks in. In diesel vehicles, a so-called control flap is used. In the lower part of the page, we go further into the function and structure of a throttle valve. In addition, we explain how you can recognize a defect and what to consider when buying and replacing throttle valves.

Design and function of the throttle valve

The throttle valve influences and regulates the intake air volume in the engine. Depending on how wide the valve is open, more or less fresh air or fuel/air mixture flows into the cylinders. Thus it determines the speed and the power output of the engine. The air flow is controlled by turning the round, movable disc. When the driver presses the accelerator pedal, the flap is opened. Older vehicles used to have mechanical flaps. These were moved by means of a cable / Bowden cable. Newer vehicles are now equipped with electric throttle valves. With these the position of the accelerator pedal is transmitted electronically to the engine control unit via a servomotor. This requires a throttle valve sensor, such as the throttle valve potentiometer.

The throttle valve sensor detects the opening angle of the throttle valve and transmits the information to the engine control unit via an electronic signal. This sensor is usually located on the throttle valve axis. There are two types of throttle valve sensor: The throttle valve switch - this contains two switches which detect the charge states "idle" and "full load". The second type is the throttle potentiometer. This has an adjustable resistor which detects the opening angle of the throttle and transmits this to the control unit. The aim of the whole is an exact and effective air-fuel mixture and thus a lower fuel consumption.

Why are so-called control dampers needed in diesel vehicles?

In principle, a diesel engine does not need throttle valves, as mixture preparation is carried out by other methods. The control valve used fulfills other tasks and primarily serves to increase the intake manifold vacuum, meters the exhaust gas recirculation rate, reduces jerking when the engine is switched off and ensures regeneration of the soot particle filter.

What does the idle regulator have for a task?

As the name suggests, the idle regulator is used in idle speed. For example when the car is driving very slowly in first gear or when additional consumers are switched on in idle, such as the air conditioning. The idle regulator then provides an increased air supply by activating the solenoid valve. This prevents the engine from dying off when idling.

How can you tell that the throttle valve is defective?

Normally it is not necessary to change the throttle valve, as it is designed for the lifetime of a vehicle. Therefore a replacement is only carried out in case of a defect.

The following things can indicate a defect:

• Engine shakes
• A reduced engine power
• Speed fluctuations / slow decrease of speed
• switching off the engine at idle
• Uneven acceleration
• Increased fuel consumption

The above mentioned symptoms can be caused by deposits of dirt particles or oils in or on the throttle valve. Often it is only dirty and only needs to be cleaned. It must be ensured that dirt as well as liquid does not get into the intake manifold or the engine. In addition, the teach-in process must be carried out again. In most cases a suitable diagnostic device is necessary for this. The symptoms can also occur with a defective throttle valve sensor or throttle valve potentiometer.

What do I need to consider when I want to buy a new throttle valve and can the change be done by myself?

Due to the scope of the repair, we recommend leaving the replacement to a specialist workshop. The engine cover, intake hose and other parts must be removed to access the throttle valve. The throttle valve must also be completely removed so that neither dirt nor liquids penetrate into the intake system. After the replacement of the throttle valve the new one must also be re-trained on some vehicles. On some vehicles the teach-in process is automatic, this depends on the vehicle. If a new throttle valve is required, you will find the ORIGINAL spare part suitable for your vehicle in our shop.

We are happy to help you find the right throttle valve! Especially with ORIGINAL throttle valves it is very important that the exact matching part number (installed ex works) is used. To do this, you can contact our Customer Service by e-mail, using the contact form or via Live Chat and WhatsApp, stating the 17-digit chassis number of your vehicle.