Idle speed sensor: principle of operation, device, types, photo, purpose

Types of idle speed sensors

Today, automobile manufacturers present several types of IACs:

Solenoid sensor. It works based on electromagnetic force. After voltage is applied to the coil, the core is hidden. The valve flap allows air to flow freely inside. Once the solenoid is turned off, the peripheral channel is blocked.

The operation of the sensor is monitored due to the dynamics of the frequency of command signals. A certain amount of air has its own frequency equivalent, which allows you to clearly regulate the operation of the IAC.

Stepper. The technical structure of such a sensor includes a ring magnet and windings. Due to the stepwise supply of voltage to each element, under the influence of a magnetic field, the main rotor rotates. The executing mechanism, depending on the position of the rotor, controls the opening of the air duct.
Rotary sensor. Control occurs through alternating frequency pulses. It is very similar in structure to the solenoid IAC, but the main place in the design is occupied by the rotor itself.

Nuances of choosing a sensor

The original idle speed controller is marked as XX-XXXXXXXX-XX. The last two characters define the compatibility label.

More details about them:

odd characters (03 and 01) are interchangeable, as are even characters (04 and 02);
device group data cannot be replaced, that is, even ones cannot be replaced with odd ones.

You can identify a fake low-quality idle speed sensor by several criteria:

there are no distinctive marks on the device packaging;
the tip of the rod has a dark shade;
the yellow sticker on the device body has no frame;
original sensors are equipped with a thin black seal, while counterfeits are equipped with a thick red ring;
the body of a low-quality device will be 1 cm shorter;
non-original sensors are equipped with a white spring instead of a black one, its turns are sparser;
There are no caps with a diameter of 3 mm on the case rivets.

Purpose of the IAC regulator

The idle air regulator is used exclusively in electronic ignition systems:

the proportions of the fuel mixture in the injector are determined by the on-board computer;
the amount of gasoline or diesel fuel for each cylinder is measured by the ECU;
sensors are installed in the electronic ignition
DPKV
(crankshaft),
TPDZ
(throttle valve),
Mass air flow sensor
(air), DD (detonation), based on the signals of which the fuel pump is activated and the ignition is distributed to specific cylinders;
when the gas pedal is released, the fuel damper is completely closed, the proportions of the fuel mixture are violated, combustion products are sucked back into the combustion chamber due to the pressure difference between
intake
And
exhaust manifold

Purpose of the IAC
Based on the results of the air sensor signals, the controller makes a decision to further enrich the fuel mixture with air, ignoring the readings of the throttle sensor at this moment.

The chip on the IAC transmits a signal from the ECU; a bypass channel opens in the idle air regulator, through which air passes in the injector or additional fuel in the diesel engine. Engine speed is leveled, piston and crankshaft wear is reduced

How not to fall for a fake when choosing an IAC

If the check shows that the regulator is broken, you should be prepared to replace it, which was mentioned just above. If we talk about IAC on VAZ, then the idle speed controllers OMEGA and KZTA (Kaluga) stand out in terms of quality and reliability. Of course, we are talking about original parts, not fakes.

You can identify a fake IAC by the box in which it is packaged. Cheap packaging, strange font, bad, smudged printing - all this indicates a fake.

The fake part itself also has flaws. As a rule, this is play in the guide bushing and the cap itself. Over time, the backlash only increases, which negatively affects the operation of the IAC. In addition, there may be a gap on the regulator body, due to which air leaks will appear. Poor soldering of the contacts is also possible.

You can protect yourself from counterfeiting with the help of the manufacturer himself, who applies protective measures. This may be a unique spare part code, which can be verified via SMS or on the website.

Operating principle

In carburetor engines, the problem of enriching the mixture when starting the internal combustion engine was solved by a starting handle and shims. With the advent of electronic ignition, this is done by the idle air regulator in conjunction with other sensors and the computer. Its operating principle is as follows:

IAC calibration is performed by the ECU controller automatically after detecting this sensor in the system;
in fact, the IAC is a stepper motor with a conical needle in a special hole in the throttle valve bypass channel;
The IAC contact does not transmit any signals to the “brain” of the machine, but receives them from the controller, therefore it is not a sensor, but an actuator - an electric valve;
in turn, the on-board computer “sees” that there is not enough air in the fuel mixture based on the signals from the mass air flow sensor, compared with the signals from the air flow sensor;
Voltage is applied to the XX regulator, the needle leaves the channel, and the missing amount of air enters the mixture for mixing.

Operating principle of the IAC
In addition, the ECU receives signals about the temperature of the coolant and oil in the system. When starting in the cold season, it is necessary to warm up the engine to operating temperature in order to reduce wear on friction parts, so the IAC channel opens slightly to enrich the mixture for the injector, even without the driver pressing the gas pedal.

At the moment of start, the operating algorithm is as follows:

the key turns, the ignition turns on;
the rod extends all the way, the needle blocks the bypass channel;
at the moment the rod rests against the calibration hole, the computer counts the steps backward;
voltage is applied to the windings, the valve returns to the open position.

The number of reverse steps is programmed in the device firmware. For example, for Basch modifications on a warm internal combustion engine it is 50 steps, January – 120 steps, respectively. In total, the stroke of the rod is divided into 250 steps; the further it extends from the windings of the stepper motor, the greater the number of steps the ECU will count. When purchasing a new IAC, the distance from the mounting flange to the rod needle should be exactly 23 mm.

How does the regulator work?

In everyday life, the IAC is often called a sensor, although in reality it is not one. The element is a stepper motor housed inside a non-separable housing. Only the spring-loaded rod with a cone-shaped tip protrudes outward. At the command of the ECU, the engine extends or retracts the rod to a certain distance.

The idle speed sensor is located in the throttle valve block, the working cone is extended into a small cross-section bypass channel. Since the engine starts and idles without pressing the accelerator pedal, the mentioned channel supplies air to the cylinders when the throttle is closed. The task of the IAC is to regulate the amount of air flow, blocking part of the flow area with a cone.

To better understand the issue, it is worth presenting the operating principle of the idle speed sensor in the form of an algorithm:

After the driver turns on the ignition, the controller activates the governor motor, forcing the idle air passage to open. The ECU calculates the opening amount using a temperature sensor - if the engine is cold, the rod will move back more.
At the moment of startup, the injectors supply an enriched mixture to the cylinders. Then the amount of fuel is reduced so that the engine does not “suffocate” and stall. The speed is monitored by the control unit using a crankshaft position sensor.
The volume of air entering through the IAC is taken into account by the mass air flow sensor located on the inlet pipe, while increased crankshaft speeds are maintained (1200–1500 rpm).
Using the temperature sensor, the control unit “sees” that the engine is warming up and gradually reduces idle speed, giving the command to the IAC to cover the cross-section of the bypass channel. When the temperature reaches an acceptable value (60 °C or more), the regulator maintains the speed at 850 rpm.

Signs of a malfunctioning idle speed sensor

The main problem will be that this part is not equipped with any type of self-diagnosis. On the control panel you will not see a flashing light or an inscription that will indicate a malfunction of the IAC. Everything will depend on your attentiveness and how you feel and hear your car. Signs that indicate that a part is worth checking include:

the car began to stall at idle (uneven idle speed);
a sharp drop or increase in speed during idle;
when driving on a cold engine, the speed does not increase;
When changing gear, the car stalls.

There are few reasons why the IAC failed. As they said earlier, this is a fairly reliable part, but it can still fail. There may be several reasons for the malfunction:

The guide needle is worn.
Broken contacts inside the part.
The needle is clogged due to poor quality fuel.

As we all know, fuel is one of the most important components of the operation of both the engine and the car as a whole, and the idle speed sensor is no exception. Most of the reasons for part failure are the use of gasoline with impurities.

A malfunction and inadequate operation of the XX sensor is indicated by any changes in the engine speed. If the part fails completely, you will not be able to start the car without using the gas pedal. And such a procedure will negatively affect the operation of the vehicle as a whole. Manufacturers do not recommend this practice for nothing.

Conclusion

The idle air control is a small component of the throttle body that does a very serious job. Thanks to the regulator, the car engine does not require a long warm-up and runs well at idle. The approach to idle control has changed significantly over the past 10-15 years. Electronic throttle valves, which do not require a regulator, are becoming increasingly popular, since the valve itself copes with its tasks. Such chokes are not afraid of low temperatures and mechanical failure, since there is practically none. As for cars with classic engine throttle valves, choosing the appropriate regulators today is quite simple. They will be released for a very long time.

Preventive measures

In order not to encounter a complete malfunction of the regulator in the future, it is worth periodically carrying out the cleaning process described above.
How often to carry out the cleaning process depends on how actively you use your vehicle. If the car is a work vehicle, it is recommended to check and clean the sensor once a year; if you use it only for yourself, once every two years will be enough. But, of course, do not forget about the signs of a part malfunction; if they appear, do not delay. This will help you avoid complete failure of the part and enjoy a high-quality ride. Together with you, we come to the conclusion that the part is unpretentious, simple in its functionality and use. Don’t forget: timely detection of a malfunction is the key to overall vehicle productivity. The full operation of the engine depends on the serviceability of each of its components, and if you neglect any part, including the idle speed sensor, this can lead to more labor-intensive repair processes and failure of the entire car.

Checking the idle speed sensor

Diagnosing the part is quite easy, but pay attention to a few points. The first problem may be removing the part; most manufacturers attach the XX sensor to screws, and in extreme cases they can be drilled out, but in some variations the part is mounted on varnish. If your regulator is secured with varnish, be careful not to forcefully remove it, as this may damage the intake part of the car. In your case, it would be correct to completely dismantle the throttle assembly and only then disconnect the IAC.

The easiest way to check is, of course, visual inspection. During a visual inspection, the first thing you should pay attention to is whether the needle is dirty. Also pay attention to the condition of the contacts and the throttle valve itself.

If broken wires are found, they must be returned to their place. Solder them and, to avoid corrosion, treat them with varnish.

It would be appropriate, if possible, to check the IAC with a multimeter or a homemade tester. You can check the resistance with a multimeter, and use a homemade tester (you can make one from a mobile phone charger) to check the stroke of the regulator rod.

If you find that the motor is damaged, the rod is completely worn out, or the cone needle is worn out, the part will need to be replaced. Don’t be too upset about this, the cost of the part will only be about 1000 rubles.

Symptoms and causes of IAC malfunction

Signs of a malfunctioning idle speed sensor appear as follows:

during a cold start, the crankshaft speed does not increase, which is why the engine runs unstable and tends to stall;
there is a drop in the number of idle revolutions after a significant increase in the load on the generator - turning on headlights, electric heaters, and so on;
the engine periodically stalls when any gear of the manual transmission is switched off (the symptom manifests itself while driving);
The speed “floats” - it spontaneously increases and decreases.

Important point! There is a misconception that a regulator failure is necessarily accompanied by the inclusion of the Check Engine indicator on the dashboard. Since the element is an actuator, the light warning option is not provided in all cars.

If the car shows signs of IAC malfunction in the form of floating engine speed at idle, advanced diagnostics may be needed. A spontaneous change in the crankshaft rotation speed occurs for many reasons - failure of a sensor, air leaks, gas distribution malfunctions, and so on. It is better to start troubleshooting by checking the regulator.

IAC failure occurs for three main reasons:

Open or poor contact in the power supply circuit. Simply put, there are problems with the wiring.
Breakdown of the stepper motor due to natural wear and tear. In this case, only replacing the idle speed sensor will help.
Contamination of the rod and cone with oil deposits.

There is a fourth reason - problems with the electronic control unit. The problem is quite rare and is accompanied by additional symptoms - increased gas mileage, unstable operation in all modes, difficult starting, and the like.

Oil deposits reach the rod thanks to secondary gases sent by the crankcase ventilation system for re-combustion. The more worn out the engine, the more deposits accumulate on the working cone. As a result, moving the rod becomes difficult; in advanced cases, the mechanism simply jams.

Method for checking the sensor using a multimeter

The most reliable and common way to check the functionality of the sensor is to use a multimeter. But to do this, the regulator must first be removed. Typically, it is secured with several screws near the throttle sensor, but on some cars it can be secured with a special solution or varnish.

It is impossible to dismantle the IAC using force, since there is a high risk of damaging the intake system. In such a case, you will have to remove the entire throttle assembly.

To check the electric motor, it is necessary to measure the resistance of the windings. The multimeter contacts must be connected in turn to each of the windings A and B, C and D. If everything works properly, the data obtained will fall in the range of 40–80 Ohms.

As an additional check with a multimeter, the contacts can be swapped. The sensor, in this case, should indicate an open circuit.

IDLE SENSOR CONTAMINATION

Often the cause of improper operation of the idle air regulator is its contamination. In such a situation, you can replace the sensor (which is inexpensive) or clean it. Cleaning the idle speed sensor takes place in two stages: You need to moisten a cotton swab with a special product (for example, which is used to clean a carburetor) and use it to clean the contacts of the sensor. This must be done carefully so as not to damage them; The remaining parts of the regulator can be cleaned mechanically using the product indicated above. Moisten a toothbrush with it, for example, and carefully clean the needle, rod, spring, removing accumulated dirt.

Replacement

To work you will need:

The new regulator is suitable for your VAZ 2114;
Rags;
Phillips screwdriver;
13mm wrench;
Carburetor cleaner;

Having the necessary tools and materials, you can get to work.

Park the car on a level surface and apply the handbrake.
Raise the hood and secure it securely to avoid unnecessary injury.
Disconnect the negative terminal from the battery. IAC is an electrical appliance so this activity is mandatory.
Remove the protective cover from the power supply.
Loosen the clamp slightly to remove the rubber tube from the air filter fitting. This is necessary so that the tube does not interfere.
Remove the clamp holding the air filter tube. The ripples separate and move slightly to the side.
The fastening screw of the cable from the accelerator pedal to the accelerator (accelerator) needs to be loosened slightly.
The rag removes all dirt near and on the throttle body itself.
Treat the throttle retaining nut and IAC retaining screws with the almighty WD40. This will make disassembly easier.
Remove the throttle valve assembly. To do this, unscrew the two nuts with a 13mm wrench.
Remove the sensor connector from the terminals.
If there is dirt at the contact points between the DXX and the throttle body, be sure to wipe it off with a rag.
Using a screwdriver, unscrew the two fasteners that connect the throttle assembly and our desired sensor.
Remove the regulator from the mounting slot.
Wash the entire throttle body with carburetor cleaner.
Place the new regulator in the same position as the disassembled DHX.
Apply engine oil to the new rubber gasket that should come with the IAC.
Tighten the two screws and make sure the adjuster fits snugly into the throttle body.
Replace the remote control and check that the nuts are tight.
Connect the connector to the terminals of the device.
Reinstall the cable, tube and tube. Tighten all clamps securely.
Replace the engine casing.

Replacement procedure

After assembly, a very important stage remains: calibration of the new IAC. To do this, you need to connect the battery and turn on the ignition. 10 seconds is enough. During this time, the electronic control unit is calibrated.

That's all, the new regulator is ready for use. To avoid problems with replacement, watch the video tutorial.

Repair

It is not always possible or even the desire to spend money on buying a new device. Regardless of the reasons, you can try to fix a faulty or faulty inactive sensor using a repair method.

Try washing the old sensor.
To do this, disassemble it and thoroughly clean all contacts with a cotton swab dipped in carburetor cleaner.
In addition, the rod, needle and spring are generously treated with detergent.
A toothbrush can easily clean greasy areas with carb cleaner.
Rinse the device again and then return it to its place.
At such events it was not unusual to achieve an excellent result, the idle was working again as before.

But this is the simplest repair option, which is not always worth relying on. There is a more complex, but at the same time more effective option for repairing the controller yourself in the event of the slightest breakdown:

Disassemble the sensor, clean its external elements, as indicated in the previous repair method;
Remove the three pins securing the sensor body;
Disassemble the regulator housing as carefully as possible. Very slowly and carefully so as not to damage the contacts;
After disassembly, you may find a broken weld. In this case, the wire is welded and the welding site is treated with special anti-corrosion paint;
If there are gaps in the regulator body, they are eliminated using sealant. This prevents air from entering through the valve.

If, when disassembling the device, problems arise with winding or the needle is worn out, repair will not help. You'll have to completely change your MAC.

The problem of malfunctioning idle air control is quite common in the case of the VAZ 2114. This element cannot be called the weak point of the car, but no one wants to deal with such a breakdown. As, indeed, with any other malfunction. But where can I get it from them?!

Malfunctions of an inactive sensor are externally similar to the occurrence of malfunctions in other groups of injectors. But at the same time, checking its performance is sometimes much simpler than systematically sorting each node for faults. In addition, its diagnosis will not be difficult even for a driver who has no experience working with an auto electrician.

Cleaning the needle and bypass channel

To provide access to valve parts, removal of the IAC is required using the following technology:

disconnecting the block from the connector;
cleaning the connector contacts and plug with a cotton swab soaked in WD-40;
unscrewing screws with a curved screwdriver;
removing the regulator to check the condition.

IAC cleaning

Attention: There is no need to disassemble the regulator, just spray the spring and rod with needle with WD-40 spray, wait for it to dry, and at the same time clean the throttle bypass channel.

The adjustment is made by the on-board network controller itself. However, for stable operation of the engine, you should check the distance from the mounting flange to the protruding needle cone. By default it should be 23 mm.

Do-it-yourself IAC diagnostics

The causes of malfunction are conventionally divided into electrical and mechanical. First, you need to dismantle the regulator and conduct a visual inspection of it to eliminate contamination with waste carbon and its possible impact on the performance of the power unit. If repairs are necessary, the part must be cleaned, thoroughly dried and lubricated with silicone. The step option is washed with a spray can, which is not an economical method.

After removing the assembly, you should pay attention to the rubber ring or gasket, provided that it is installed on the throttle or pipe. When mounting the part externally, a connection is made to the intake manifold. It will be necessary to inspect its rubber elements for deformations and tears. Any part found to be defective must be replaced.

Alternative diagnostic methods

If you have a special device for detecting faults, for example, an adapter with suitable software, diagnostics are much easier. OpenDiag can even be used on a smartphone and is available in both paid and free versions. When starting the software, it is worth paying attention to the current and desired throttle valve positions. Their performance will change accordingly along with the revolutions. If you turn on the additional electrical unit, you can notice changes in the IAC data, but the motor power should not change. First of all, the values are updated on the line of the desired position, and then on the current one. When the values change, the RPM value should also change. Otherwise, there is a possibility that the idle speed control is inactive or there is an air flow leak.

For faster verification, you need to open the menu in the upper left corner. This is control over the operation of actuators. Using the parameters “current idle position” and “desired idle position”, you can enter your values, which should immediately be displayed on engine operation. If there is no response to intervention, a faulty section of the stroke with obvious dysfunction of the regulator can be immediately identified.

You can also use a multimeter to diagnose the wiring. With the engine turned off, the connector is removed from the regulator. DC voltage values of 0-20 V are entered into the measuring device. Then the voltage value of the connector is measured. The acceptable value is 12 units.

It is also worth checking the IAC resistance. To do this, you need to fix the values after removing the terminal from the sensor between terminals C and D, A and B. The limit on the multimeter is set to 200 Ohms. With an acceptable resistance, the norm will be 50 Ohms, and the resistance between the terminals will tend to infinity.

Diagnostics can be carried out using the throttle assembly. Having dismantled it together with the sensor, you need to monitor its operation when activating/deactivating the ignition system and connecting the valve connector. The work of the needle, the presence of extraneous sounds, and the uniformity of the work process are subject to close attention.

Main aspects of checking IAC

We figured out how to clean the idle speed sensor, now we’ll take the time to diagnose it. Like cleaning, testing can be done at home.

How to check the idle speed sensor:

Find the IAC and remove it along with the wires. Unscrew several clamps that secure the throttle assembly with the receiver, then move these elements apart by about 1 cm.
Using a diagnostic tester, check the IAC circuit - now you should make sure whether there is voltage in the network or not. Connect the tester probes to contacts A and D - as a rule, they are marked on the body. Having connected the probes, you need to activate the ignition and look at the results. The best option is 12 volts. If this parameter is lower, then most likely the problem lies in a poor battery charge, and if it is completely absent, then it is quite possible that the problem lies in the control unit.
Make sure that the circuit is on the IAC itself. To do this, the tester's probes must be connected to pins A and B, and then to C and D, and you need to set the tester to ohmmeter mode. When checked, the diagnostic parameters should be about 53 ohms. Then the same actions should be repeated with other pairs of contacts, for example A and C, and the resistance should tend to infinity (the author of the video is Ivan Vasilyevich).

There is another option; for this, checking the idle speed sensor must be carried out with the IAC removed. Connect the power cable, then touch the end of the needle with your finger (no force required). During shutdown, the regulator should begin to extend the needle fully, so when you turn, there should be a slight push of the finger.

As you can see, in general, diagnosing a device is not that difficult, but for a quality test you need to understand how to use the tester. If you have no idea how to do this, it is better to seek help from an electrician, but in practice, after studying the instructions for the multimeter, there should be no problems with its use. Of course, the tester itself must be working, otherwise the readings will not correspond to reality and you will only get confused.