How the Throttle Position Sensor Works

How the Throttle Position Sensor Works – Now it’s time to talk about how the throttle position sensor works. In the EFI system, a car uses a computer which we often call the car ECU. The car’s ECU in its work receives a lot of input from various sensors.

Read more: ECU vs ECM vs PCM

How the Throttle Position Sensor Works

One of the most talked-about engine performance is the throttle position sensor or we often call it the TPS sensor.

How the Throttle Position Sensor Works
This is an example of a throttle position sensor from a BMW car.

But how does the throttle position sensor or TPS sensor actually work? This time I will discuss more the problem of the TPS sensor including how it works.

The throttle position sensor (TPS) is used to monitor the position of the throttle valve in an internal combustion engine. The TPS sensor is usually located on the throttle valve spindle so that it can directly monitor its position.

The TPS sensor is a potentiometer, providing a variable resistance depending on the throttle valve position (and hence the name throttle position sensor).

Sensor signals are used by the engine control unit (ECU) as input to its control system. The ignition timing and fuel injection timing (and other potential parameters) are changed depending on the position of the throttle valve, and also depending on the rate of change of that position.

What is ECU?

The engine control unit (ECU) is input into the control system. The ignition timing and fuel injection timing (and other potential parameters) are changed depending on the position of the throttle valve, and also depending on the rate of change of that position.

Engine control unit ECU BMW e46. Source: PIECES-OKAZ.COM

Some throttle valve modifications have a built-in end switch. They are closed throttle position sensors (CTPS) and often include a wide-open throttle (WOT) sensor mounted on the accelerator pedal.

The throttle position signal can be generated from a simple contact (TS) or potentiometer (TPS), and also from a combined TS/TPS sensor. Some systems use these two types as separate elements.

Type of Throttle Position Sensor or TPS Sensor

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There are several types of throttle position sensors or TPS sensors. According to its construction, there are three types of throttle position sensors. The three are as follows.

  1. with end switches
  2. potentiometer type
  3. combination of both above.

How the Throttle Position Sensor or TPS Sensor Works

Next, we will discuss how the throttle position sensor works or how the TPS sensor works as follows.

How the Throttle Position Sensor Works
Inside of Throttle Position sensor. Source: NAPA

TPS provides onboard controller information about idling, deceleration, acceleration rate, and fully open throttle valve (WOT) condition. TPS is a three-wire potentiometer.

In the first wire, a +5V voltage is applied to the resistive layer of the sensor and the second wire closes the sensor circuit to the ground (car body). The third wire is connected to the potentiometer wiper, thereby changing the resistance and therefore the signal voltage is returned to the onboard computer.

Based on the received voltage, the onboard computer can calculate idling (below 0.7V), full load (approximately 4.5V), and throttle valve opening speed.

Full Load Condition? how the throttle position sensor works

At full load, the integrated computer provides further enrichment of the fuel mixture. In deceleration mode (throttle valve closed and engine speed above a certain RPM), the onboard computer shuts down fuel injection. Fuel supply is resumed after the engine speed reaches its idle value or when the throttle valve opens. Some cars allow adjustment of these values.

THROTTLE SENSOR (TS)

The TS informs the onboard computer of the idling status. Usually, it has a second contact for the fully open throttle valve (WOT) state.

In most cases, the internal computer provides additional enrichment of the fuel mixture at idle and with the throttle valve fully open.

Each TS contact has two positions – open and closed – where the onboard computer detects three different engine states:

  • Throttle valve closed (idle speed contact closed)
  • Throttle valve opened (idle speed contact and WOT open)
  • And throttle valve fully open (idle speed contact open and WOT contact closed)

Some cars allow a TS set. Under many conditions, the TPS sensor may be damaged or experience problems that interfere with overall engine performance.

You can recognize it through the TPS sensor Faulty sign. By recognizing these signs you can then perform a TPS sensor inspection procedure to further confirm it and then repair or replace your car’s TPS sensor.

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