How does the throttle sensor work? Damage to the throttle sensor. Operating principle and structure

As you know, the VAZ 2110 car was produced with injection and carburetor engines. The injectors are equipped with an impressive number of sensors, the performance of which determines the functionality of important units. Therefore, if they break down, problems may arise in moving, power decreases, fuel consumption increases, and much more.

A prime example of an important sensor is the throttle position sensor. Today we’ll talk about it in more detail.

Why is it needed?

The throttle position sensor is responsible for determining the current throttle position. Depending on this, the fuel supply system changes the amount of fuel supplied in one or another operating mode power unit.

If problems arise with it, you can contact a service station so as not to waste your energy and nerves. But in practice, changing the TPS yourself is quite simple, plus you will save a decent amount of money.

The required regulator is located on the side of the throttle pipe on the throttle valve axis.

Features of work

The TPS is essentially a variable resistor, one output of which is supplied with 5 Volt power. The second contact is connected to ground, and the third is connected to the controller.

When you press the gas pedal, the voltage changes. The sensor monitors the output voltage on the controller, thereby regulating and monitoring the quality of the supplied air-fuel mixture. This directly depends on the opening angle of the damper itself.

If for some reason this regulator fails, a disaster will not occur, since temporarily its functions will be taken over by another sensor - mass flow air.

This does not mean at all that the TPS can not be changed. Each regulator has its own functions, so there is no point in transferring the tasks of the TPS to the MAF.

Malfunctions

There are several telltale signs of trouble that may indicate that there is a problem with the throttle valve.

• High performance idle speed;
• When the gear is switched off, the engine may stall;
• When the car picks up speed, the car jerks and jerks are felt;
• Acceleration dynamics deteriorate significantly;
• Floating speed occurs at idle.

It should be noted that similar symptoms may also be characteristic of the failure of other components - the idle speed control or the ignition module, for example. Therefore, you first need to check the TPS.

Checking the status of the regulator

Next, let's talk about how you can check this throttle valve sensor. The event is necessary because it allows you to understand whether all the troubles are really due to it, or whether the problems arose due to the failure of other elements of your car.

It’s not uncommon for novice car owners to make hasty conclusions based on the primary signs of a breakdown. Hence the extra renovation work, costs.

To check the current status of the throttle position sensor you need to:

• Measure the voltage at the output of the slider, turning on the ignition and opening the idle contacts;
• If the test shows that the voltage is more than 0.7 volts, then the sensor has indeed failed;
• Open the damper completely. In normal condition, voltage readings should be no more than 4 volts;
• Measure the variable resistor for resistance;
• To do this, connect an ohmmeter or a multimeter in ohmmeter mode to the power supply and output;
• Slowly begin to turn the throttle;
• At the same time, monitor the readings on the device;
• If, as the damper opens, the resistance also changes slowly, then the unit is working properly.

If you find during the test that the sensor is faulty, you only need to replace it. It cannot be repaired.

The resistive layer along which the slider moves wears off over time due to friction. Because of this, the regulator begins to produce incorrect data, the characteristics of the supplied mixture change, and engine performance deteriorates.

Replacement

In fact, changing this sensor is crazy easy. So don't rush to send your car to the station maintenance. Everything can be done with your own hands, the quality will not suffer from this.

1. To remove the throttle position sensor, you first need to find it.
2. As we have already noted, the required unit is located on the side of the throttle pipe on the throttle valve axis.
3. Having found the element, pick up a shaped screwdriver.
4. Using this simple tool, unscrew a couple of bolts that hold the device.
5. Please pay special attention on the gasket that is available under the old regulator. We do not recommend using it again; it is better to immediately buy a new one. Often the gasket is already included with the throttle sensor itself.
6. After removing the old sensor, you can slightly clean the place where it is installed if there is dirt there.
7. Next, a new sensor is installed along with a new foam gasket and the bolts are tightened.
8. Try to tighten the fasteners as far as possible, otherwise the new throttle sensor will quickly lose its effectiveness. The work will have to be done again.
9. There is no need to make any adjustments after replacement.
10. The zero mark on the controller will determine that the throttle is completely closed.

What to choose?

When replacing, many more or less experienced car owners have a question about which regulator is better to install. After all, there are two types.

In pursuit of savings, many forget about the importance of quality. But it should be in the first place when choosing spare parts when repairing a car.

TPS is an important, but easy to replace device. The repair operation will take you no more than an hour, even if you are just beginning to learn the joys of repairing your car yourself.

But under no circumstances delay repairing the sensor, otherwise this may negatively affect the operation of the engine, its service life and the cost of fuel, which you will overuse due to incorrect data from the sensor to the ECU.

This article will discuss what a throttle sensor is. You will learn the structure of this unit, consider the main breakdowns of all types of sensors. There are, as you know, several types. But they all perform the same functions - they send a signal to electronic unit control about what position the damper is in. These data affect the operation of the engine as a whole. In particular, on mixture formation - the correct ratio of gasoline and air, which is supplied to the combustion chamber.

Sensor types

It is worth noting that there are several types - contact, non-contact, with limit switches. The latter type, however, is practically not used anywhere, since the design is morally outdated. With their help, it is possible to provide only two types of signal - the throttle valve is open or closed. But in older engine control systems, such sensors performed their function and allowed the engine to operate in normal mode. But today the most common are contact and non-contact TPS. These are the ones that should be considered to study the principles of operation.

Design of throttle position sensors

If you disassemble the contact sensor, you will find in it the same elements that are in the variable resistor. An arcuate resistive layer along which the slider moves. There is some resistance between the slider and the two edges of the resistive layer. It changes depending on the position of the slider. Non-contact sensors have a similar design, but there is no mechanical connection between the resistive layer and the slider. From all that has been said, we can conclude that contactless devices are the most reliable. There is no mechanical contact in them, therefore, the durability of the mechanism increases. Well, now it’s worth studying in more detail the throttle sensor, its malfunctions and methods for eliminating them.

Main failures of the TPS

Well, now it’s worth considering the most common malfunctions of this unit. Most frequent breakdowns occur due to the fact that the resistive layer is erased. The fact is that the slider gradually wears it out. Moreover, this breakdown occurs not only in contact sensors, but also in non-contact ones. And maximum wear begins in the place of the resistive layer where the slider is most often located, that is, at the very beginning. You can even diagnose this breakdown visually. Often a defect occurs due to a break in the power or signal wires. Most sensors used in a car are powered by 5 Volts.

Determining the health of the sensor

The malfunction can be determined by measuring the voltage at the sensor. When the slider is in its extreme position, the sensor will receive a voltage of up to 0.5 Volts. If you open it completely, the voltage increases to 3-4.5 Volts. But please note that some cars have sensors that have an inverse characteristic at the output. If the throttle valve is closed, the device output has a maximum voltage value. At the same time, the voltage decreases when the throttle valve opens. Pay attention to what type of TPS is installed in your car. This will prevent you from confusing normal parameters with a sensor failure. Study the features carefully electronic system control the engine of your car. Here's how to test the throttle sensor on any car. The main thing is to find out what type of signal is at the output.

Symptoms of failure

And now about how a TPS failure manifests itself. You don't need to visit a diagnostician to determine the problem. If the engine starts to run unstably, stall at idle speed or when you press the gas, the engine begins to over-throttle, and sometimes even stops completely, you have obvious problems with the TPS. In this case, when engaging 1st or 3rd gear, the speed may drop. But the latter symptoms very often occur if the throttle valve adaptation is not performed correctly. The second case is typical when installing non-original spare parts. It is quite possible that the sensor was replaced with an analogue whose quality is very low. It is worth noting that the operation of non-original sensors is very dependent on temperature. When heated, the output signal changes.

If on a cold engine there is one output value, then when warming up at idle speed this same characteristic begins to steadily increase. In this case, the electronic control unit will not be able to respond in time to changes in voltage coming from the device. Consequently, when changing gears, you will experience unstable engine operation. The only way to temporarily fix this problem is to turn the ignition off and on again. The electronic control unit maintains the extreme values ​​of the TPS power supply. Therefore, there will be no failure during switching. Don't rely on chance. If such a malfunction occurs, it must be corrected immediately. Whether you do it yourself or at a service station is up to you.

Removing TPS from a car

No adjustment of the throttle sensor will be necessary if you are installing an original replacement part with the same characteristics as the one that failed. You know the most common causes of TPS failures, you have figured out which elements most often fail. But how can you save on repairs? It is this issue that is worth considering in more detail. It should be noted that it is impossible to restore the resistive layer on your own. If your throttle position sensor has failed, you will need to completely replace it. To replace the TPS, you must first remove the old one. In this case, turn off the power by removing the terminals from the battery. The wires going to the sensor must also be disconnected. Next, the fastening bolts are unscrewed, after which the TPS is removed.

Installing a new device

Then the new device is installed, connected to the electronic control unit, only after this can the terminal be put on battery. You will not need to change the ECU settings if the replacement is done in this order. No factory settings will be reset, the engine will operate in the mode in which the electronic control unit is programmed. But please note that you only need to install original spare parts. If you have a car foreign production, then the VAZ throttle sensor will not suit you. It is advisable to purchase the device in specialized stores or from official dealer. Please note that counterfeit products can be purchased on the Internet and in markets. Therefore, be vigilant and careful when choosing a seller.

Conclusions

As you can understand from this article, a lot of problems can be caused by such a small sensor, which indicates the throttle position to the electronic control unit. But don’t panic if such a nuisance suddenly happens. Everything can be repaired, everything can be restored. Of course, you will get minor inconveniences with this breakdown. But you can replace the TPS yourself within a few minutes. Assuming you have a known good device. It should also be mentioned that the throttle sensor, the price of which for VAZ cars ranges from 400-500 rubles, can be found in any spare parts store.

Issue injection engines contributed to the emergence of various electronic devices. Including sensors that collect information regarding the performance of a particular system.

Thus, control is taken over by an electronic unit that monitors the performance of all engine systems using these sensors. The malfunction of even a minor part leads to undesirable consequences in the operation of the entire car. One such part is the throttle position sensor.

TPDZ - what is it?

The throttle position sensor signals to the controller what position the throttle valve is in when the accelerator pedal is pressed.

This device allows the controller to more accurately dose and supply the fuel mixture. If the sensor malfunctions, the information is transmitted to the controller in a distorted form. This may cause engine malfunctions and lead to excessive fuel consumption.

The controller registers the location of the throttle valve by changes in voltage. A 0.7 V signal forces the controller to switch to idle mode. If the voltage is less than 0.7 V, this indicates that the damper is completely closed. And if the voltage is about or more than 4 V, then the damper is fully open.

Where is it located

In order to be able to check the TPS if necessary, you need to know where it is located. Its location is on the throttle body and is connected to its axis. There is a special groove on the axis, for which a cross-shaped socket is provided on the sensor.

The sensor housing is attached to the throttle body using bolts. The sensor is installed on cars with injection engines.

Signs of a malfunction of the TPS

Any part fails sooner or later, as evidenced by characteristic signs. TPS is no exception.

Typical signs of a malfunctioning throttle position sensor may include:

• the engine idles at high speed;
• clearly observed high consumption fuel;
• in neutral gear the engine stalls;
• the car jerks when accelerating;
• sometimes the indicator may light up and stay on for a long time Check Engine;
• The engine starts with difficulty.

All these signs indicate that the TPS is faulty and, therefore, requires immediate replacement of the part.

Video - some signs of a malfunctioning throttle position sensor:

How to check

If some signs of a malfunction of the TPS are detected, but it is completely unclear what they indicate, then you can independently check its performance.

Usually, if there is a malfunction of the TPS on dashboard The Check Engine light comes on. Therefore, first you should start the engine and if the indicator does not light up, you need to crawl under the hood to the sensor itself.

To check its functionality, it is not necessary to remove it; everything can be done on site. To do this, you need to connect two wires of the multimeter to terminals B and C of the sensor. The corresponding marking is available.

After this, you can start smoothly, slowly turning the throttle using the drive sector. If the sensor is working properly, the device readings should also change smoothly without sudden jumps. Typically from 2 to 8 kOhm. Resistance measurements should be made with the engine turned off.

Video - checking TPS:

Now you should measure the voltage. To do this, first connect the negative of the multimeter to the engine ground. After this, you need to start the engine and connect the positive contact of the device to terminal A of the sensor, also following the markings. The voltage is measured, which should be within 5 V. If the device readings are different (less than 5 V), this indicates a malfunction of the power circuit or the unit itself electronic control engine.

If during the test all the instrument readings were normal, then there is nothing to worry about. Otherwise, the TPS needs urgent replacement.

Replacement

If the check shows that the TPS is faulty, then it needs to be replaced. You don't need many tools for this, all you need is skillful hands and a Phillips screwdriver.

The sensor should be replaced by turning off the engine and disconnecting the negative from the battery. Then you need to disconnect the sensor connector, which has a lock. Then unscrew the two screws that secure the sensor to the throttle assembly. After this manipulation, the sensor is easily removed from the throttle valve axis.

Video - replacing the throttle position sensor on a VAZ2110, 2114, 2115:

Installation of a new device should be done in reverse order. In this case, you need to make sure that the throttle valve itself is closed. Usually, when a new TPS is purchased, an O-ring is included in its package. It is installed between the sensor and the throttle pipe. Remember to remove the old ring before installing the new sensor.

Once in place, tighten it with the machine screws until the O-ring is completely compressed. Now all that remains is to connect the connector and secure it with the latch.

After this, disconnect for 5 minutes. This is done to reset the old sensor parameters in the ECU, which in most cases are retained.

Adjustment

In some cases, it becomes necessary to adjust the throttle position sensor. This procedure may be an alternative to replacing it. And it should be carried out when there are obvious signs of malfunction. They were mentioned above.

Video - adjusting the throttle position sensor on a VW Passat:

To adjust, you will also need a multimeter with wires. You shouldn’t do everything by eye, as the electronic control unit will receive incorrect data. Accordingly, it will incorrectly dose the air-fuel mixture with all the ensuing troubles.

Before adjustment, the sensor mounting holes need to be slightly widened. This is done so that the sensor can be rotated around its axis.

An important point: before each time removing the TPS or disconnecting its connector, you must turn off the ignition, and before each measurement, turn it on.

The sensor connector can be removed, or you can expose a small section of the connector wires hidden under the casing. Only these two wires are of interest, usually blue (plus) and black (ground). They will be needed to measure voltage during the adjustment process. If the connector is removed, then you need to connect the multimeter wires to the corresponding contacts on the sensor.

Having connected the wires to the contacts of the sensor (they should be well secured), install it in place. Do not tighten the fastening screws completely: so that the sensor does not dangle, but can be rotated. Now you need to carefully rotate the sensor counterclockwise or clockwise until the following readings are established on the device: 0.55-0.56 V. If necessary, the mounting holes must be widened to increase the angle of rotation.

When setting the required value, the TPS should be securely secured. After this, perform a voltage test. If necessary, insulate previously exposed sections of wires.

If you are faced with a situation where the engine idles unevenly or the car periodically stalls for unclear reasons, then this behavior of the power unit may be to blame throttle position sensor malfunction. You should not immediately go to a service station, because this problem can be eliminated on your own.

New throttle position sensor

In this article we will look at the main signs indicating failure of this sensor, we’ll find out how to check the TPS, and also get acquainted with its design. This manual is suitable for car owners VAZ 2110, 2114, Priora, Kalina and even Renault Logan.

is a device that is designed to accurately distribute the amount of fuel mixture entering the engine combustion chamber. Its use in modern engines allows you to increase the efficiency of the car, as well as increase the efficiency of the power unit. It is located in the fuel supply system on the throttle valve axis.

This is what the TPS design looks like

Species

On modern stage development of automotive technology, the following types of TPS are presented on the market:

The latter structurally have resistive contacts in the form of tracks along which the voltage is determined, while non-contact ones carry out this measurement based on the magnetic effect. Sensor differences are characterized by their price and service life. Contactless ones are more expensive, but their service life is noticeably longer.

Operating principle

As stated above The sensor is located near the throttle valve. When you press the pedal, it measures the output voltage. In the case when the throttle valve is in the “closed” position, the voltage in the sensor is up to 0.7 Volt. When the driver presses the gas, the throttle axis rotates and accordingly changes the inclination of the slider at a specific angle. The sensor response is manifested in a change in resistance on the contact tracks and, consequently, an increase in the output voltage. When the throttle is fully open, the voltage is up to 4 Volts. The data is for VAZ cars.

These values ​​are read by the vehicle's electronic control unit. Based on the data obtained, he applies changes to the amount of fuel mixture supplied. It is worth noting that this entire procedure occurs almost instantly, which allows you to effectively select the engine operating mode, as well as fuel consumption.

Signs of sensor malfunction

If the TPS is in good working order, your vehicle It works without uncharacteristic jerks or jerks and quickly responds to pressing the gas pedal. If any of these conditions are not met, then there may be a sensor malfunction. This can be determined by the following signs:

• Starting the engine is difficult both hot and cold;
• Fuel consumption increases significantly;
• When driving, the engine jerks;
• At idle, the speed is often higher than normal;
• The car's acceleration is sluggish;
• Sometimes there are extraneous sounds similar to popping noises in the intake manifold area;
• The power unit may stall at idle;
• The Check indicator on the instrument panel blinks or stays on.

Most often, the sensor becomes unusable due to exceeding its service life due to wear-out. Contact group has a coating and, accordingly, wear is characteristic of it. Those TPS that operate on a non-contact principle do not have this drawback and, accordingly, last much longer.

In order to finally make sure that it is necessary to replace this part, you need to be able to check the sensor.

The throttle position sensor is located on the throttle body. Serves to measure the degree of throttle valve opening.

Throttle position sensor.

The sensitive element of the throttle position sensor is a potentiometer, the axis of which is rigidly connected to the throttle valve axis. The power terminals of the potentiometer are supplied with reference voltage+5 V and “ground”, and the moving contact of the sensor is a signal one. The output signal of the throttle position sensor is one of the basic ones for the engine control unit to calculate the required amount of fuel, to determine the current operating mode of the engine and to calculate the optimal ignition timing. For example, in engine start mode, the amount of fuel supplied is calculated based on engine temperature, the degree of throttle opening and the actual crankshaft speed. With the engine running and the throttle valve closed, the engine control unit goes into the mode of stabilizing the engine crankshaft speed - the idle speed maintenance mode. The specified crankshaft rotation speed depends on the coolant temperature, the engine load and the vehicle speed and is regulated by changing the degree of opening of the idle speed control and changing the ignition timing. To eliminate the “failure” in the delay in the set of revolutions at the moment of sharp opening of the throttle valve, the engine control unit briefly suppliesadditional fuel. If the throttle valve is open more than ~70%, the engine control unit enters the full load, providing maximum engine power by preparing a slightly enriched air-fuel mixture. When the throttle valve is suddenly closed while the vehicle is moving, the engine control unit activates the forced idle mode (or engine braking mode) by completely cutting off the fuel supply until the engine speed drops to a certain value. The remaining relatively stationary throttle positions between the "idle support" and "full load" modes are called the "partial load" mode of the engine. In this mode, the engine control unit maintains an optimal fuel-air mixture ratio close to 1:14.7, through the use of a signal feedback from oxygen sensors.

Checking the sensor output throttle position.

Diagnostics of a potentiometric-type throttle position sensor consists of checking whether the output voltage of the sensor corresponds to the actual position of the throttle valve over the entire range of its possible positions. To view the voltage oscillogram of the sensor output signal, the oscilloscope probe connector must be connected to any of the analog inputs No. 14 of USB Autoscope II, the black alligator clip of the oscilloscope probe must be connected to the ground of the engine of the vehicle being diagnosed, the probe probe must be connected in parallel signal terminal of the sensor.

Wiring diagram for a potentiometric-type throttle position sensor.

1. connection point for the black alligator clip of the oscilloscope probe.
2. oscilloscope probe connection point.

In the "USB Oscilloscope" program window, you must select the appropriate display mode, in this case "Control => Load user settings => Potentiometer". The sensor is checked with the ignition on and the engine stopped. A voltage waveform of the sensor output signal should be recorded. To enable oscillogram recording, in the "USB Oscilloscope" program window, you must select "Control => Record" after selecting the "Potentiometer" mode and turning on the ignition. After turning on the oscillogram recording, you need to open the throttle valve as smoothly as possible until it is completely open, and then close it just as smoothly. Next, to stop recording the oscillogram, in the “USB Oscilloscope” program window, you must select “Control => Recording”. After recording is completed, the recorded waveform can be examined in detail. When the throttle valve is closed, the voltage value of the output signal of the position sensor must be in a certain range, most often - 0.25...0.75 V. As soon as the throttle valve begins to open smoothly, the voltage value of the sensor output signal should also smoothly increase synchronously with the increase in the throttle valve opening angle.

Voltage oscillogram of the output signal of a working throttle position sensor. The ignition is on, the engine is stopped, the throttle valve opens smoothly and closes quickly.

When the throttle valve is fully open, the sensor output voltage value should be in the range of usually 3.9...4.7 V. Some engine management systems use potentiometric-type throttle position sensors with an inverse output characteristic. When the throttle valve is closed, the sensor output voltage is high, and when the throttle valve is open, it is low. In many engine control systems, where the throttle valve position is set using an electric drive (over the entire range of possible positions, or only in idle mode), the current throttle valve position is determined using two potentiometers at once, structurally combined. One of the potentiometers has a direct output characteristic, and the other potentiometer usually has an inverse output characteristic. In addition, many throttle valve assemblies with a built-in electric drive are often additionally equipped with a micro-idle limit switch, which is activated when the accelerator pedal is fully released by the driver.

Voltage oscillograms of the output signals of a healthy dual throttle position sensor of an engine management system with an electronic throttle valve actuator. Ignition on, engine stopped, throttle opening, throttle closing.

potentiometer signal having

1. Oscillogram of the output voltage inverse output characteristic.
2. Voltage oscillogram of the output signal of a potentiometer having a direct output characteristic.

1. A: In this case, it corresponds to the voltage of the output signal of the potentiometer, which has an inverse output characteristic when the throttle valve is closed and is equal to ~4 V.
2. A: The voltage value at the time indicated by the marker. In thisIn this case, it corresponds to the voltage of the output signal of the potentiometer, which has a direct output characteristic when the throttle valve is closed and is equal to ~890 mV.

The presence of two potentiometers in the throttle position sensor serves to increase the accuracy of measurement of the current throttle position, to accurately recognize sensor faults by the control unit, as well as to increase the reliability of the throttle valve assembly - if one of the potentiometers fails, the engine control unit determines the current throttle position dampers based on a signal from a working potentiometer. There are paired potentiometric throttle position sensors, where both potentiometers have a direct output characteristic. The output signal of one potentiometer varies over a range of throttle positions from “fully closed” to “partially open” (for the BOSCH MONO Motronic engine management system this range is from 0% to 30%). The output of the other potentiometer varies over a throttle valve position range from "partially open" to "fully open" (for the BOSCH MONO Motronic engine management system this range is from 17% to 100%).

Voltage oscillograms of the output signals of a working paired throttle position sensor of the BOSCH MONO Motronic engine management system. Ignition on, engine stopped, throttle opening, throttle closing.

1. Oscillogram of the voltage output signal of a potentiometer operating in the range of throttle valve positions from “fully closed” to “partially open”.
2. Oscillogram of the voltage output signal of the potentiometer operating in the range of throttle valve positions from “partially open” to “fully open”.

This sensor design is used to increase the accuracy of measuring the current position of the throttle valve at small opening angles. High accuracy of measurement of the current throttle position in the BOSCH MONO Motronic engine management system is very important, since this system not equipped with anythe intake manifold absolute pressure sensor or the air flow sensor. Therefore, the amount of load on the engine and the corresponding required amount of injected fuel are determined by the crankshaft rotation speed, the throttle opening value, the engine temperature and the incoming air temperature.

Typical faults throttle position sensor.

The moving contact of the potentiometric sensor mechanically moves along the contact resistive layer of the sensor, which over time can cause the destruction of this contact resistive layer. In this case, at some positions of the sensor movable contact, the sensor output voltage value may not correspond to the actual throttle position.

Potentiometer track with a “worn” contact resistive layer (this illustration shows the measuring potentiometer of the volumetric air flow sensor).

As soon as the driver sets the throttle valve to a position in which the slider of the throttle sensor potentiometer hits an area with a damaged contact resistive layer, sudden jerks in engine operation occur. The engine control unit perceives voltage changes in the defective area as a signal for the engine's rapid acceleration mode or fuel cut-off mode. The nature of the influence of the malfunction on the operation of the engine control system depends on what engine operating modes and at what throttle valve opening angles the malfunction appears. If the sensor readings are violated when the throttle valve is closed, this leads to instability of the idle speed - after releasing the accelerator pedal, the engine may stall, or, on the contrary, the idle speed may be very high. If the sensor readings are violated at any other throttle position, this causes sudden jerks in engine operation at moments when the throttle valve acceptspositions at which there is a discrepancy between the sensor output signal and the actual position of the damper.

Voltage oscillogram of the output signal of a faulty throttle position sensor. Ignition on, engine stopped, smooth opening of the throttle, smooth closing of the throttle.

In most cases, the discrepancy between the throttle position sensor output and the actual throttle opening angle occurs at the throttle position "fully closed" and "partially open", which causes the engine to malfunction in idle mode.

Voltage waveform of the output signal of a faulty throttle sensor. Ignition on, engine stopped, soft opening positionthrottle valve.

If the contact resistive layer of the sensor is damaged throughout the entire range of throttle positions, the nature of engine operation becomes unpredictable. Sensor malfunctions caused by destruction of the contact resistive layer of the sensor are eliminated by replacing the throttle position sensor with a new one. Another typical sensor malfunction is an increased dependence of the sensor output voltage on the temperature of its body. This malfunction is a consequence of installing a low-quality throttle position sensor at the stage of replacing a worn-out sensor with a new one or during the production stage of the car. This malfunction appears after the engine warms up with the throttle valve fully closed as an increase in engine speed at idle. A characteristic sign of a malfunction is the possibility of temporarily eliminating it by turning off and restarting the engine. When the ignition is turned on, the engine control unit records ("remembers") the current value of the output voltage of the throttle position sensor and takes it as the voltage corresponding to the fully closed throttle. After starting the engine, this voltage value serves as a sign that the engine control unit is closed.throttle when the driver fully releases the accelerator pedal. If the output voltage of the sensor coincides with the value recorded when the ignition is turned on, the engine control unit switches to the mode of stabilizing the engine speed at idle. If the temperature stability of the sensor is not satisfactory, the engine may not operate properly at idle. For example, at the moment the ignition is turned on, when the engine is cold (the throttle position sensor body is cold), the output voltage value of the sensor in question is 500 mV. The engine control unit records this value as corresponding to a fully closed throttle valve. At the moments when the output voltage of the sensor again coincides with this recorded value of 500 mV, the engine goes into idle speed stabilization mode. As the engine warms up, the sensor housing also warms up, and if, as the temperature of the sensor housing increases, its output voltage also increases, then a moment may come when, with the throttle valve closed, the output signal voltage will significantly exceed the value recorded when the ignition is turned on, and will be equal to, for example , 550 mV. In this case, when the driver fully releases the accelerator pedal, a voltage of 550 mV will be supplied from the sensor instead of 500 mV, which will no longer correspond to the signal of a fully closed throttle valve. As a result, the engine control unit will no longer go into idle speed stabilization mode. If the driver now turns off the ignition and then starts the engine again, the engine control unit will record the new current value of the throttle position sensor voltage of 550 mV with the body already warm and take it as the voltage corresponding to the fully closed throttle valve. Now, engine operation with the throttle valve closed will be stable until the temperature of the throttle position sensor housing changes again. Diagnosis of this malfunction comes down to comparing two sensor output voltage values ​​with the throttle valve fully closed. The first value must be measured when the temperature of the sensor body is close to the current air temperature value (the engine has not been running for at least 3 hours). The second value must be measured when the engine is fully warmed up to operating temperature(the electric cooling fan will automatically turn on for at least three times). This malfunction can only be eliminated by replacing a low-quality sensor with a high-quality one. Some engine control systems use optical position sensors instead of potentiometric-type position sensors. A typical malfunction of these sensors is the penetration and accumulation of contaminants in the cavities where the optical elements are located and on the optical elements themselves. This malfunction can be eliminated by cleaning it from contaminants, but only in cases where the design of the sensor allows it to be disassembled and reassembled. Recently, in some engine control systems, instead of potentiometric-type position sensors, non-contact “linear” sensors operating on the Hall effect are used. These sensors do not have the disadvantages of a resistive layer, but at the same time have their own typical faults. The most common defect in the Hall effect throttle position sensor is in areas with a non-linear dependence on the change in the sensor output voltage. On the voltage oscillogramoutput signal when the throttle valve is gradually opened, this malfunction appears as an “L-shaped step”. This "step" can cover a significant range of possible throttle positions. When the throttle position changes smoothly within this range, the voltage values ​​of the sensor output signal do not change. There may be several such steps throughout the entire range of possible throttle positions.

Voltage oscillogram of the output signal of a faulty position sensorHall effect throttle valve.

This malfunction can only be eliminated by replacing the sensor with a working one.

Throttle Valve Switch.

Some earlier engine control systems used throttle limit sensors based on micro-limit switches. Micro switch "idle" and micro switch "full load".

Throttle position sensor, the measuring elements of which are two microswitches.

Each of the limit micro-switches can take one of its two possible states - “closed” or “open”. Depending on the current state of the microswitch, the voltage of its output signal can take a value corresponding to either low level signal (usually this value is 0 V), or the corresponding high level signal (usually this value is 5 V or 12 V). Due to relatively rapid mechanical wear, the sensor microswitches may stop working over time; this malfunction especially often occurs with idle speed microswitches. To eliminate this defect, it is enough to periodically re-adjust the position of the sensor housing relative to the throttle body so that the idle speed micro-switch changes its state immediately after the throttle valve begins to open. Another common malfunction of limit micro-switches of some types of position sensors is the formation of microcracks in the area where the output terminals of the switch are soldered to the sensor connector. This malfunction occurs on cars with significant mileage, due to the impact of mechanical loads in the area where the switch terminals are soldered to the sensor connector. If the sensor is designed to be disassembled and reassembled, this problem can be corrected without having to replace the sensor. It is enough to re-solder the output terminals of the micro-switch in the area of ​​soldering with the sensor connector using a soldering iron. Checking the serviceability of the limit micro switch is carried out by measuring the resistance of the sensor using an ohmmeter. The resistance of an open microswitch should tend to infinity. When the micro switch is closed, its resistance should not exceed value 1 Q. In this case, additional attention should be paid to the stability of the resistance of the micro-switch in the state"closed" when it is activated several times. After each switching of the switch to the “closed” state, the ohmmeter should show the same sensor resistance value with deviations of no more than 0.1 Q. Changing resistance values ​​of the microswitch in the “closed” state may be a sign of the formation of microcracks in the area where the output terminals of the switch are soldered to the sensor connector, or a sign of burning of the sensor contacts. There are throttle position sensors made using a technology similar to that of potentiometric throttle position sensors - based on a resistive layer. The resistance of such a sensor when its state is “closed” can take values ​​from 0.1 Q up to 10 kQ and more. Such sensors are often structurally combined in a common housing with a potentiometric-type throttle position sensor.

Throttle position sensor is a potentiometric type with a built-in limit position sensor that is activated in the “fully closed” position of the throttle valve.

Such sensors usually have a 4-pin connector. Three terminals of the connector are connected to the potentiometric type throttle position sensor, the fourth terminal of the connector is connected to the output of the throttle valve limit position sensor. The other terminal of the throttle valve limit position sensor is connected to one of the sensor's supply terminals, usually to the sensor ground terminal.