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The throttle valve is a very important component in every gasoline engine. It is operated using the accelerator pedal and thereby regulates the engine speed. Without it, it would not be possible to run a gasoline engine at different speeds.

Structure of the throttle valve

The throttle is located between the air filter and the intake manifold. Since it is in a tube, it is round in shape. It is located directly in the middle so that the angle can be adjusted. So it can be opened and closed steplessly. This is the structure of modern injection engines. In older carburetor engines, the throttle valve is located directly in the carburetor.

Function of the flap explained in the video

If the accelerator pedal is depressed as far as it will go, the throttle valve opens completely. It then releases the entire cross section of the intake pipe. If the accelerator pedal is not pressed, it closes the intake pipe. There are various technical solutions to ensure that the engine still gets some intake air. In some versions there are stops that prevent complete locking. But there are also models in which the intake air is routed through bores next to the throttle valve. There are usually adjusting screws in it so that an exact amount of air can be set for idle operation.

How a throttle works

To understand how it works, a little explanation about how a gasoline engine works is required. A piston moves downward during the intake stroke. This creates a vacuum in the cylinder's combustion chamber. Since the intake valve also opens during the intake stroke, air is drawn in through the air filter. In the case of a carburetor engine, fuel is then also sucked into the combustion chamber at the same time. In the case of an engine with injection, the fuel is supplied separately.

In order for the fuel-air mixture to remain ignitable, it must always reach the cylinder combustion chamber in a ratio of 1: 1. To burn one gram of fuel efficiently, one gram of air is also required. For this reason, it is not enough to simply increase the amount of fuel to increase the engine speed. This process is therefore regulated by means of an air supply. As soon as the accelerator pedal is depressed, the angle of the throttle valve changes. This allows a larger amount of air to be sucked in.

In the case of a carburettor engine, a larger amount of fuel is also sucked in at the same time. In an engine with electronic fuel injection, sensors determine the opening angle of the throttle valve. The data are transmitted directly to the engine control unit. The engine control unit uses this data to regulate the amount of fuel to be injected.

Special throttle control techniques

In modern engines, the throttle valve is usually not actuated mechanically by means of a linkage. The position of the accelerator pedal is electronically transmitted to the engine control unit. The control unit then uses additional data to regulate the optimum opening angle of the throttle valve. This makes the engine run very efficiently.

Sometimes there are several throttle valves on an engine. Sports cars have a separate throttle valve for each cylinder. These are then located directly in the intake manifold. The advantage is that a much larger amount of air can be sucked in. This is the only way that the engines in the sports cars can achieve their high levels of performance.

Possible problems with the throttle

There is normally no wear and tear on a throttle valve. In most cases, it lasts as long as the engine itself. However, if a car frequently drives short distances, deposits of combustion residues can form in the area of ​​the throttle valve. This affects the function.

The driver notices that the engine is no longer running smoothly and is reluctant to accelerate. However, this problem can be remedied with little effort. With the help of a special throttle valve cleaner, contamination in this area can be quickly removed.

Where can I order spare parts?

The prices for a new component vary between 80 and 300 euros. Every now and then you should clean the flap with a cleaning spray. This can also be ordered from Amazon. A spare part can be ordered online at the following shops:

Article last updated on April 5, 2021