Checking and replacing the sensors of the engine management system. Crankshaft Position Sensor Top Dead Center Sensor

Hello dear readers! I am sure that among you there are experienced motorists with a decent driving experience, but often even they do not know what a crankshaft position sensor is and what its role is in the life of a car. Of course, in any vehicle there are a lot of all sorts of systems, components and individual parts that you don’t immediately remember, and if you have heard a similar name, but you can’t figure it out yet, we will help you with this now. Spend just a few minutes of your time and you will find out what the crankshaft sensor is responsible for, what its main tasks are and what problems can arise during its operation.

crankshaft position sensor device

First of all, in order for you to realize the seriousness of this topic, it must be said that the crankshaft sensor is the only sensor that, if it breaks, the car will definitely not start, or rather the engine will not be able to start its work.

(crankshaft position sensor) is also called a synchronization sensor, since it is it that allows e-governance(controller) to synchronize its work with the gas distribution mechanism of the car engine, thereby providing the formation of signals for clock, cyclic and angular control of the injection of the combustible mixture and the ignition system.

The principle of operation of this device is not the most complicated and consists in creating inductive signals. When the teeth of the crankshaft pulley pass near the sensor core, pulses appear alternating current. In other words, the crankshaft position sensor is electromagnetic sensor, which synchronizes the operation of the fuel injectors and ignition in the fuel injection system. That is, we can say that the DPKV is the main link, without which the operation of the named system is impossible.

The operation of the crankshaft position sensor is combined with the synchronization disk (they work in pairs), due to which the above-mentioned angular impulses are created. The sync disk has 60 teeth, 2 of which are missing, which ensures the generation of synchronization pulses, and the angle of one tooth, together with the interval to the next, is 6 degrees from the placement of the crankshaft. The beginning of the 20th, after the notch, the tooth coincides with TDC ( top dead point) of the first or fourth cylinder. Also, this device provides for a gap between the teeth of the disk and the end surface, the value of which should be within 1 mm (the use of appropriate washers will help), and its sensing element is presented as a winding made of copper wire on an insulated coil with a magnetized core located inside.

The whole design of the crankshaft sensor consists of the following elements:

- plastic or aluminum case cylindrical shape having a sensitive element;

Base equipped with a flange and a hole for mounting;

Shielded communication cable (length 610 mm.); a three-pin connector molded in the cable.

Install the crankshaft position sensor on the bracket, next to the generator drive pulley. During the installation process, it is important not to forget about maintaining the gap between the device itself and the toothed pulley.

What is the crankshaft sensor responsible for and signs of its breakdown

In the previous part of the article, we have already dealt with the principle of operation of the crankshaft position sensor, and also learned about its main function - the creation and synchronization of inductive signals. Now, I think, everyone understands what the failure of this part can lead to. Therefore, in order to avoid trouble, especially before long trips, it will not be superfluous to diagnose the device and timely carry out repair work(unless, of course, you have to), but before that you need to know what exactly to pay attention to.

First of all, it is worth understanding that the crankshaft sensor itself will not "jump": either it works without interruption, or it does not work at all. In the latter case, this process is irreversible and it will not “turn on” again. There can be several reasons for the failure of this device. Most often, its functioning is adversely affected by constant loads at high temperatures(make the structure more vulnerable), high humidity, mechanical influences and a sharp change in temperature, which gradually render the part unusable.

The most common type of breakdown of the DPKV is the slow partial wear of the wiring of the device, however, you can find out in more detail the cause of the failure and the nature of the malfunction using a special diagnostic scanner that any service station should have. To understand that it is necessary to study the sensor for damage, the signaling device will help you dashboard"check engine" and if it's not the wiring, then the sensor will have to be replaced. True, such a function is available only in modern cars, and if the model vehicle older, figure it out If there is a problem, the following symptoms of a DPKV malfunction will help:

- lack of idling (the car stalls);

Unstable work on idling;

Lack of reaction to the ignition start (engine does not start);

The engine often "stalls" in the process of moving the vehicle;

The power of the power unit drops quickly;

When the engine is loaded, detonation occurs.

Noticing at least one of listed problems, it is best to immediately seek help from specialists who are well versed in the principle of operation of the crankshaft position sensor and will be able to more accurately determine the location of the breakdown, in addition, they have all the necessary equipment for this.

If, for some reason, you cannot or do not want to resort to the help of professionals, you can diagnose DPKV yourself. To do this, first of all, it is necessary to remove the sensor from the engine and visually inspect it - there should be no dents or cracks. Then, the winding of the device is subject to a resistance test, which a multimeter connected to the sensor terminals will help you to complete. Resistance indicators should be in the range of 600-900 ohms. Also, there is another way to check with the named measuring device, in which any metal object and if the multimeter displays voltage surges, then the sensor is working.

In the case when the engine has stopped starting, first it is worth checking the presence of power and the appearance of a spark on the injectors. Further, a high-voltage wire is removed from the spark plug and brought to the motor, after which the starter is scrolled. If a spark does not appear, then it can be assumed that the sensor is faulty. However, when doing such a manipulation, one must be extremely careful, since in the event of a spark, a strong current discharge can lead to a breakdown of the electronic motor control unit.

The presence or absence of power on the injectors is determined using the same multimeter or the most ordinary light bulb 12 W connected to the injector connector. If the sensor is working, then during the rotation of the engine by the starter, voltage will appear and the light will light up, otherwise we can talk about a malfunction of the DPKV. Also, a similar conclusion can be drawn if, after a short operation, the engine stalls, in this case, the crankshaft pulley may be the culprit.

What is the function of the crankshaft sensor?

To date, the design various sensors may differ from each other, depending on the model of the vehicle and its manufacturer, but regardless of the device and the principles of its operation, all DPKV retain a single general function- synchronization of the engine injectors or starting the car. If this function is violated, the system produces an incorrect creation of the fuel-air mixture, due to which the performance of the vehicle is completely lost.

If we describe in detail the principle of operation of the crankshaft position sensor, then it can be expressed in such a way of generating pulses in which they will correspond to the moment when the teeth pass near the ends of the device. The voltage amplitude and pulse repetition rate obtained as a result of such an action is directly proportional to the rotation of the engine. Therefore, when the engine is idling, the voltage amplitude should be less than 6 watts, and if the engine is rotated by the starter, this figure will rise above 5 watts.

Another function of the crankshaft position sensor is to determine the position of the gas distribution mechanism, and the information supplied to the engine management system directly affects the ignition and injection of the fuel mixture. Nowadays, there are several types of crankshaft position analyzers (sensors) that are equipped with cars manufactured today. The most popular of them include:

Magnetic sensor. His functional advantage there is autonomy (it is not required for work additional source energy);

A sensor based on the Hall effect. The process of its operation is as follows: at the moment of approaching the variable magnetic field, the current movement begins and the synchronization disk intercepts the pulse. Most often, just such a sensor is installed on modern cars.

Optical sensor. It is able to intercept the flow of light formed between the receiver and the diode, after which the impulse is transmitted to the engine control unit. Thanks to these signals, the electronic unit controls the injectors and the entire operation of the fuel pump.

As you can see, although DPKV are divided into types that have certain features of the workflow, their main function remains unchanged.

Serves to control the internal combustion engine. With its help, the electronic unit on the microprocessor reads information. More specifically, he determines what position the crankshaft is in, based on this, he sees where the pistons are located at a particular point in time. This setting is required for correct operation injection and gas distribution systems.

Main properties of DPKV

This device has several names, and all are equivalent. The most common term is "crankshaft position sensor", abbreviated as DPKV. Sometimes it is called a top dead center sensor, a little more often a phase or synchronization sensor. But no matter how you call it, a breakdown leads to the fact that the engine stops and cannot continue to work. The reason is that it is he who determines at what point in time it is necessary to start a discharge on the electrodes of the spark plugs.

In the event that the engine stops, does not start, although even the rubber timing belt is intact and transmits movement to the camshaft, it can be judged that the DPKV is malfunctioning. In addition, on the dashboard, if the sensor fails, the control lamp, signaling the presence of any malfunction in the ACS. To properly diagnose this device, you need to know the principle of its operation and device.

The design of the DPKV and its main elements

The VAZ crankshaft position sensor has a fairly simple circuit. It has several main elements:

The DPKV is installed in the immediate vicinity of the crankshaft pulley, which has teeth. Moreover, there should be 60 of them in total, but in one place two are cut out. Thanks to this gap, the control unit sees when the piston of the first cylinder is at TDC.

The principle of operation of the sensor

The work of the DPKV is based on the principle of electromagnetic induction. When the crankshaft rotates, the pulley with teeth moves near the sensitive surface of the sensor. At the moment when the metal tooth passes near the DPKV, a weak pulse begins to be generated in the winding. There are 60 such current surges per revolution (according to the number of teeth on the pulley). But there is a small gap, as mentioned earlier.

Due to the fact that there is a gap between the teeth, at a certain moment the time interval between pulses increases. The ECU sees that the crankshaft begins to make the next revolution. In this case, the crankshaft position sensor 2110 counts 20 pulses. This is just the moment when in the first cylinder the piston is located in the very top position. It is thanks to this that voltage is applied to the electrode of the candle.

Sensor installation location

Its location is on the side of the gas distribution mechanism. In this place is the alternator drive pulley, on which the teeth are applied. The sensor is located on the side of the engine, which is closer to the bulkhead of the engine compartment. Not good convenient location to replace, you will need to remove the right wheel. The device is connected to the on-board network using a wire, its length is 0.7 meters.

By the way, you can do a simple anti-theft system using the signal from the crankshaft position sensor. To do this, it is enough to install a simple relay with normally open contacts in the switching circuit. Mount a small, but strong magnet, and in the castle - reed switch. Such simple circuit will be able to protect the car from theft, since the slightest distortion or complete interruption of the signal from the sensor leads to a complete engine stop.

Troubleshooting

It is immediately worth noting that many factors affect the operation of the sensor. Moreover, it is necessary to carefully monitor so that there are no interference from high voltage wires. If they are, then an error may appear on the dashboard, although the engine will operate in normal mode. The presence of a warning is misleading, as no visible signs appear.

All you need to check is a multimeter. The main thing is to be able to measure the resistance of the sensor winding. To do this, disconnect the plug and connect a multimeter to it. The resistance value should be approximately 0.85-0.9 kOhm. If it deviates from this in any direction, then there is a short circuit between the turns. As a result, the signal is distorted, the ECU does not perceive it. It is also common for wire breaks to occur. As a result, there is no signal at all.

Sensor replacement

To remove the old one and install the new one in its place, you will need to lift right side car. After that, unscrew the bolts on the wheel to gain access to the installation site of the DPKV. In fact, the crankshaft position sensor, which is replaced only according to this scheme, can be dismantled without removing the wheel. True, there is no convenience. Therefore, it is better to raise the car on a jack.

When replacing, do not forget that the gap between top pulley tooth and the sensitive surface of the sensor should be in the range of 1-1.5 millimeters. Otherwise, it will not work correctly.

This is what the crankshaft position sensor is. Its price is approximately 300-350 rubles. It is always better to have a spare in the glove compartment, so that its breakdown does not come as a surprise to you.

Instructions for checking the TDC sensor

1. If the TDC sensor is defective, then the fuel injection sequence will be incorrect. As a result, the engine stalls, idles unevenly (unstable engine speed), and has poor acceleration (throttleness).

2. If the TDC sensor signal appears when the ignition is turned on (the key is in the “ON” position) and the engine is not started, then the sensor is probably faulty or the engine electronic control unit is faulty.

Instructions for checking the crankshaft position sensor

1. Engine speed at idle (when the throttle switch is in the "ON" position). Models for Europe and General Export: 4G13 engine:


At -20°С	1500- 1700 rpm
At 0°C	1350-1550 rpm
At 20 °C	1150-1350 rpm
At 40 °C	940- 1140 rpm
At 80 °C	650 - 850 rpm
4G9 series engines (except MVV):
Coolant temperature	Speed
At -20 °С	1380- 1580 rpm
At 0°C	1330-1530 rpm
At 20 °C	1250- 1450 rpm
At 40 °C	1000- 1200 rpm
At 80 °C	700 - 900 rpm
Engine 4G92-SOHC-MVV:
Coolant temperature	Speed
At -20 °С	1450- 1650 rpm
At 0°C	1350- 1550 rpm
At 20 °C	1300-1500 rpm
At 40 °C	1100- 1300 rpm
At 80 °C	600 - 800 rpm

Note: if the tachometer uses the principle of calculating the speed from the ignition signals, then it will only show half of the actual value. To get the actual idle speed, multiply the tachometer reading by two.

2. If sudden jolts are felt while driving or the engine suddenly stalls while idling, try moving the crankshaft position sensor connector while the engine is idling. If the engine has stalled, then it may be bad contact in the sensor socket.

3. If the signal of the crankshaft position sensor appears when the ignition is turned on (the key is in the “ON” position) and the engine is not started, then the sensor or the electronic engine control unit is probably faulty.

4. If the sensor output is 0 rpm while cranking with the starter and the engine does not start, the crankshaft position sensor may be defective or the timing belt may be broken.

5. If the sensor output is 0 rpm while the starter is cranking and the engine does not start, then there may be a malfunction in the primary circuit of the ignition coil due to a malfunction in the circuits of the ignition system, the ignition coil and / or the power transistor.

6. If the engine is idling even when the crankshaft position sensor reads out of specification, then the cause is usually a non-sensor failure, such as:

a) Faulty engine coolant temperature sensor.

b) Faulty idle speed control servo.

c) Incorrect adjustment of the base idle speed.

Wiring check (SOHC motors)

1. Disconnect a socket of the distributor of ignition.

2. Disconnect the connector of the power supply (depending on the model year: connector "B" of the ignition switch on the model before 1994; connector "C" of the control relay on the model before 1997; connector "D" of the control relay on the model from 1997). *

3. Check the circuit between terminal #2 of connector “A” of the electrical wiring of the distributor and the corresponding terminal of the electrical wiring connector of the power supply device (#3 of connector “B”; #2 of connector “C”; #1 of connector “D”) for an open circuit.

4. Check the circuit between terminal No. 1 of connector “A” of the distributor wiring and “ground” for an open circuit.

5. Disconnect the engine control unit connector.

6. Check for an open circuit or short to ground between terminal No. 4 (when checking the TDC sensor) or No. 3 (when checking the crankshaft position sensor) of the distributor wiring connector "A" and the corresponding terminal No. 68 of the electrical wiring connector of the electronic control unit engine.

7. Connect a socket of the block of management of the engine.