Diagnostics, cleaning and replacement of the idle air regulator

Author: Victor

Correct operation of the idle speed sensor allows you to reduce wear on the piston group, as well as the crankshaft of the car. If signs of incorrect operation of the device appear, the controller can be checked manually, with a multimeter or using a homemade stand.

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Purpose of the idle speed sensor

Purpose of IAC in vehicles equipped with an electronic ignition system:

1. The microprocessor module determines the ratio of air and fuel when creating the air-fuel mixture in the injection power unit.
2. The control unit measures a certain volume of gasoline or diesel fuel.
3. The electronic type of systems is equipped with controllers for the crankshaft, throttle position, knock and flow meter. In accordance with the readings of these devices, the fuel pump is activated. The ignition is distributed to specific cylinders of the internal combustion engine.
4. If the driver releases the gas pedal, the fuel valve closes completely. This leads to the fact that the proportions of the combustible mixture are violated. Combustion products move into the chamber when there is a difference in pressure between the exhaust and intake manifolds.

The idle speed sensor in electronic ignition systems performs the function of adjusting the composition of the combustible mixture during engine starting. Using the signals sent by the controller, the microprocessor module makes a decision about fuel enrichment. In doing so, it ignores the readings sent by the throttle control. The sensor transmits signals along the line. If necessary, a free channel opens in it through which air passes. This leads to equalization of engine speed while driving or idling.

User Roman Lozovoy presented a detailed review of the controller from the manufacturer General Motors for the Daewoo Lanos.

Principle of operation

The operating principle of the valve is as follows:

1. The control unit calibrates the sensor readings if it is detected in the system.
2. The controller itself is a stepper electric motor. It is equipped with a conical needle, which is located in a special hole in the throttle valve channel.
3. The regulator does not transmit information to the microprocessor module, but receives it from it. Therefore, it is more correct to call it not a sensor, but an actuator - a valve.
4. The control unit determines, based on a signal from the flow meter, that there is no air in the combustible mixture. It then compares these impulses with those transmitted by the TPS.
5. The regulator device receives voltage. This causes the needle to move out of the canal. the missing volume of air is supplied to the combustible mixture for mixing.

The microprocessor module also receives pulses about the temperature level of the coolant and engine fluid. If the engine starts at low negative temperatures, it must be warmed up, which will reduce wear on friction elements and units. To enrich the mixture, the idle speed sensor channel opens slightly; for this, the driver does not need to press the gas.

At the beginning of the device operation, the action algorithm is as follows:

1. The key turns in the lock and the ignition is activated.
2. The rod extends all the way. Thanks to this, the needle closes the bypass channel.
3. When the rod rests against the calibration hole, the control unit begins to count steps backward.
4. Voltage is applied to the windings. As a result, the valve returns to its original open state.

The number of reverse steps is adjusted when flashing the control unit; this indicator may vary depending on the device model. For example, on a Bosch ECU it is 50 steps, and on January modules it is 120.

User Dmitry Shark spoke briefly about the principle of operation, as well as about diagnosing the idle speed controller.

Injector

A throttle valve is used at the input of the collector device in injection engines. It is equipped with an individual controller for determining the position at a specific point in time.

When the engine starts or the powertrain stops, the following occurs:

1. The microprocessor module receives data on rotation speed.
2. Then the control unit analyzes the operation of the power unit and specifies its intended purpose.
3. Readings from the throttle controller and air are compared. The control unit determines whether the damper is closed or not. He can also “understand” which mixture is supplied to the cylinders of the power unit - lean or enriched.
4. The IAC valve opens. The air flow bypasses the damper. This makes it possible to maintain speed at a certain level, programmed in advance.

In fact, several ignition system devices are involved in this process. If the car engine stops or stalls due to problems, the operation is checked manually. This is due to the fact that there is no feedback from the IAC and the diagnostic system.

Diesel power units are not equipped with a throttle valve, so they do not use idle speed sensors, they are useless.

User Alex ZW spoke in detail about the principle of operation of the IAC controller in a car.

Design features

The valve structurally consists of:

• electric stepper motor;
• four-position rod;
• spring element;
• needles.

When IACs first appeared, they were rotary or solenoid mechanisms. Such devices had two positions - open and closed. This contributed to a decrease in the efficiency of engine speed control. Today, cars use four-step sensors, characterized by the possibility of stepwise feed through the bypass.

The idle air control itself is classified as a consumable item and is therefore considered non-repairable. It can be repaired if it malfunctions, but it will be cheaper to replace it completely.

Where is RXX located?

The device should be located next to the throttle valve and TPS. In some cars, the sensor can be fixed directly to the damper body using varnish. Sometimes the device is mounted using two bolts equipped with special mounting holes. The main thing is that the distance from the needle to the mounting flange on the installed device is 2.3 cm.

Connection diagram

Idle air controller connection diagram

One harness consisting of four cables is connected to the idle speed sensor; it comes from the microprocessor module. As a result of this connection, diagnostics may cause certain difficulties. The car owner will not be able to simply apply voltage to the terminals of the device, since the microprocessor module does this pulsed.

Why do you need a sensor?

IAC, also called idle air control, is one of the elements of the intake system of an injection internal combustion engine. Its purpose lies in stabilizing the idle speed of the engine.

For an internal combustion engine to operate, a carefully balanced mixture of fuel and air is necessary - only in this case can stable operation of the engine be ensured with the delivery of optimal power. It is with the help of IAC that the air supply to the combustion chambers of the engine is regulated, which helps to achieve the optimal ratio of proportions in the fuel mixture. Since the throttle valve is completely closed at idle, engine operation in this mode is carried out exclusively with the help of the regulator, and if it malfunctions, it is unstable.

When several electricity consumers are turned on simultaneously (air conditioning plus lights, audio system, cooling fan), a high load occurs on the generator, which is transferred directly to the internal combustion engine. The idle speed sensor helps stabilize engine operation during a sharp increase in energy consumption. This is done by increasing the air supply to the cylinders. In a similar way, high speeds are maintained when the engine warms up.

It is worth noting that if the sensor malfunctions, the quality of the fuel-air mixture is seriously impaired, leading to detonation or the inability to ignite the fuel in the cylinders. This significantly reduces engine power and increases fuel consumption.

As practice has shown, such symptoms are most often observed on injection VAZ cars. Therefore, consider the main problems and ways to solve them using the example of a car of this brand.

Signs of incorrect IAC operation

Symptoms of a regulator failure in a car:

1. The car engine stopped running. When driving or standing at a traffic light, the speed of the power unit can arbitrarily increase or fall, and then return to normal. They may freeze.
2. The car's engine began to idle. Detonation is heard - a metallic knock from under the hood.
3. While driving, there is no compensation for the increased load on the car's engine.
4. Difficulties arose in starting the power unit. If the driver has to press the gas additionally when starting, this indicates wear and the need to replace the idle speed sensor.
5. Warm-up speed is absent or maintained at an insufficient level.
6. The car engine may randomly stall for no apparent reason. This occurs when idling, releasing the gas pedal, or shifting the transmission lever.
7. The crankshaft speed may drop randomly when energy consumers are activated. For example, air conditioning or heating systems, windshield wipers, optics, etc.

What problems and difficulties arise at low speeds?

All this happens due to the fact that at this stage the air-fuel mixture is supplied to the exhaust system very slowly. As a result, it does not mix well, which reduces its effectiveness.

Quite often you can hear the opinion that when creating vehicles, designers make such calculations and developments so that the idle speed sensor works throughout the entire “life” of the power unit. But the reality is that the regulator fails quite often. As a rule, this is due to problems related to the wiring.

To avoid problems and to ensure optimal engine operation at idle speed, various devices are used; as an option, a mechanical idle speed controller is installed, which makes it possible to significantly reduce exhaust toxicity.

Main breakdowns and malfunctions of IAC

Causes of problems with the idle speed sensor:

1. Power supply circuit interrupted. This malfunction may be related to the wiring in the car, oxidation or damage to the contact elements on the block. If the connection is of poor quality, then this problem will appear periodically. It may be difficult to diagnose the device.
2. Contamination of the rod, which leads to its incorrect movement. This problem is the most common and manifests itself as a result of the accumulation of dirt deposits in the channels of the throttle assembly. If the damper is not cleaned for a long time, then the reason should be looked for on the sensor rod.
3. Failure of the electric motor. It is unlikely that such a device will be repaired; the engine must be replaced as an assembly with the regulator.
4. Destruction of the sealing element due to wear. The problem may appear immediately after replacing the sensor if an old ring is installed instead of a new one.
5. Rod wear. If the regulator is working properly, then the shutter should move without snagging, and slipping in the worm gears is not allowed. To determine the condition of the structural elements, you will have to disassemble the device.

The channel “Sdelaj Sam!” spoke about the causes and signs of malfunctions in the idle air valve! Pljus interesnoe!

Checking and repairing the Lacetti throttle assembly on video

Here is the promised video about disassembling the throttle assembly and resuscitating the IAC motor.

This is an older video where I disassembled the throttle assembly

And here is a new video where a car came to me with no idle. Here I showed how to diagnose the fault of the throttle assembly, how to check the electrical circuits inside the throttle and how to restore the IAC motor. By the way, it was in very terrible condition and had already worked for more than 450 thousand km

The report turned out to be quite large and, I hope, useful for many.

With questions and additions, you are welcome to comment below.

Peace and smooth roads to everyone!

On this topic:

+70

Diagnostics

Before checking the operation of the controller, perform the following steps:

1. The parking brake lever is tightened. Wheel chocks must be placed under the wheels of the vehicle.
2. The engine compartment of the car is opened and the negative terminal is disconnected from the battery. To do this, use a key to loosen the fastener on the lock.
3. The engine compartment is being inspected. You need to find the idle air control.
4. The block with the wire is disconnected from the device.

Manual check

This diagnostic stage is considered the simplest in terms of implementation:

1. The block with wires is disconnected from the device.
2. Two bolts are unscrewed and the regulator is removed.
3. The sensor is connected to the microprocessor unit. The controller must be held in your hands.
4. The engine is being started, it is advisable that an assistant do this. At this point, the rod should be pulled into the coil all the way. This occurs as a result of receiving an impulse from the control unit. Then it should move out a short distance.

Manually checking the idle air control valve allows you to determine the functionality of the rod. When performing this, you can make sure that the part does not bend or jam inside the device.

But this verification option does not give a 100% result. It is possible that the modification of the idle speed sensor installed on the vehicle does not match the firmware of the microprocessor unit. The rod extends, but the required amount for its extension is unknown. Therefore, the block and plug are checked, and only the latter is marked.

During a visual inspection, it is necessary to diagnose the integrity of electrical circuits and coils. You should also check the condition of the bypass channel and needle for wear.

User Igor Belov spoke in detail about performing a manual check, as well as other methods of testing the idle air valve.

Diagnostics with a multimeter

You can check the operation of the controller using the tester like this:

1. The connector with the wire is disconnected from the regulator in the engine compartment. If the car is equipped with a 1.6 liter engine, then it is necessary to unscrew the two fastenings of the throttle mechanism to the receiver in advance. Then it moves away from the end of the latter by about 1 cm.
2. First, the tester diagnoses the controller's electrical circuit to make sure whether voltage is supplied to it or not. The negative terminal of the multimeter is connected to ground, that is, the body or engine of the car. The positive contact should be connected to pins A and D, they are marked on the connector.
3. The ignition is activated and the tester readings are read. The multimeter must first be set to ohmmeter operating mode. The resulting voltage value should be at least 12 volts. If this parameter is lower, then there is a possibility that the problem is a low battery. In the event of a complete lack of power, you must ensure the integrity of the electrical circuit or control unit.
4. The ignition is turned off. The next step will be diagnosing the controller itself.
5. The multimeter is reconfigured into resistance measurement mode, its terminals are alternately connected to contacts A and B, and then to C and D. The resulting diagnostic value should be about 53 Ohms.
6. Then the resistance is measured between pairs A and C, as well as B and D. On them, the working value should tend to infinity. If the values ​​obtained are different, the sensor must be replaced.

Pulse testing on a homemade stand

You can assemble a homemade device without chips; its diagram is shown below:

1. The equipment uses 6 volt charging. It can be taken from a mobile phone.
2. Connector pads can be purchased at any specialty store.
3. During diagnostics, the sensor is first disconnected from the microprocessor module. The rod stroke is checked. If the light indicator of a homemade stand lights up brightly, this indicates that the regulator rod is faulty. If the light is on at half power, then the mechanism is working.

Scheme of a simple homemade diagnostic stand

The price of such equipment is at least 1,500 rubles. Considering the low cost of the idle speed sensor, using a proprietary stand is not economically profitable.

Sensor diagnostics

You can check the idle air valve yourself. Its faults can be divided into two parts: mechanical and electrical. There are several verification methods.

Visual inspection

First you need to conduct a visual inspection. In this way, you can detect body defects, needle wear, and carbon deposits. If deposits form, you can clean them with carburetor cleaner. It is also recommended to clean the entire throttle body as it is in a similar condition.

Using diagnostic programs

The operation of the IAC can be checked using a diagnostic adapter and special programs. For example, you can use the simplest ELM327 adapter and the OpenDiagMobile program. In the program menu you need to select the desired position of the XX regulator and watch the operation of the valve. It is better to set it at least 20 steps more than the current position.

Wiring check

For this we need a multimeter. With the engine off, remove the connector from the sensor. We set the measurement limit on the measuring device to 0-20 V DC voltage. We measure the voltage at the connector. Normally it should be 12V.

Checking the regulator resistance

To do this, we will need to measure the resistance between terminals A, B, and C and D after disconnecting the sensor terminal. We move the multimeter to the position of measuring resistance at the limit of 0-200 Ohms (Ω).

The normal value is within 50-55 Ohms. The resistance between A and C, B and D must be infinity.

Checking with throttle assembly

There is another way to diagnose IAC. To do this, you will need to remove the throttle assembly from the studs along with the sensor.

By connecting the valve connector and turning the ignition on/off, you can observe the operation of the IAC live. See how the needle works, if it is rubbing somewhere, check the evenness of the stroke, hear suspicious sounds.

How to clean the idle air control?

Cleaning a proven IAC is considered using the example of a Chevrolet Niva:

1. The engine compartment is opened and the battery is disconnected. To do this, you need to dismantle the cover of the air filter device, which is removed and put aside.
2. The block is disconnected from the air controller. The connector is located on a thick rubberized corrugation connecting the intake manifold and the air filter cover. This block is attached using a special U-shaped bracket. During dismantling, it may jump out, so you need to be careful.
3. Then the corrugation is disconnected from the intake manifold, it is fixed with a clamp. The same must be done with the rubberized pipe; it connects the corrugation to the valve cover of the power unit. The hose is fixed with an iron bracket.
4. The thin pipe connected to the intake manifold is disconnected and removed along with it. This hose is pulled onto the fitting.
5. Inside the pipes you can notice contamination in the form of carbon deposits and traces of engine fluid. All hoses must be cleaned and washed, after which they must be blown out. To complete the task, it is recommended to use a special cleaning agent or WD-40 liquid. The main thing is that there is a tube included with the cylinder.
6. The idle speed sensor itself is made in a black plastic case and is installed in the intake manifold. The plug is disconnected from it and the two bolts that secure the device are unscrewed. The procedure is performed using a short screwdriver with a Phillips head; first, traces of sealant must be removed from the bolts. When dismantling the device, you must also remove the O-ring.
7. The IAC is being cleaned, and fuel can also be used for this. The procedure is carried out using rags and cotton swabs. You cannot pour a lot of liquid into the mechanism so as not to damage it. After each cleaning, the sensor should oxidize and dry.
8. It is recommended to remove dirt from the intake manifold; dirt is removed using rags. The idle speed sensor seat is cleaned throughout its entire depth. Contaminants are also removed from the device fitting.
9. After cleaning, the entire structure is reassembled in the reverse order. A new rubber ring is installed on the idle speed sensor, after which the controller is mounted in place and fixed. The connector is connected to it, and the air filter device is installed back.

Dismantled corrugation with hoses

Removing the IAC from the seat

Cleaning the sensor with WD-40

Cleaning the idle speed sensor/controller (IAC) Chevrolet Aveo instructions

THROTTLE VALVE PROBLEMS Chevrolet Aveo T300, OPEL ASTRA J

We clean the intake manifold - spray with bolonik and wipe with rags wherever your hand can reach.

This is what I pulled out. The seat looked like this. View of the intake manifold inside.

If the throttle assembly was not removed for replacement, clean the dirty throttle assembly with carburetor cleaning fluid. Slide the spring retainer of the crankcase ventilation hose connector

Therefore, in case of these malfunctions, first try to wash the throttle valve, for example, with a solvent or a special carburetor cleaner in an aerosol package.

If this does not lead to a positive result, replace the throttle assembly. Drain the liquid from the engine cooling system, see. If you are familiar with the skill, you do not need to drain the coolant. Prepare suitable plugs to plug the hoses immediately after disconnecting them.

The loss of coolant with this method will be negligible. Loosen the clamp securing the air supply hose to the throttle body nozzle and remove the hose from the nozzle.

Cleaning the Throttle Valve. Her training after cleaning.

Slide the spring clamp of the hose tip of the crankcase ventilation system. Loosen the clamp securing the coolant drain hose. For clarity, the work hereinafter is shown on the removed cylinder head.

Squeeze the clamp on the tip of the coolant supply hose. After removing the hose, check it for contamination - it gets clogged too quickly 6.

Remove the thinnest hose that goes into the intake manifold at the junction with the manifold. It is simply pulled onto the fitting, but it is difficult to remove. So, we clean all these hoses, rinse them and blow them out. To wash them, I took a bottle like this for cleaning carburetors - it cleans very well, be sure to have a thin tube with the bottle. Now we find the IAC, it’s black plastic, located on the intake manifold.

We disconnect the connector from it. And most importantly, don’t lose the screws.

When you unscrew the screws, carefully pull the relay out of its seat, there should be a rubber sealing ring there, this also needs to be pulled out. This is what I pulled out. The seat looked like this. View of the intake manifold inside.

I wonder how to clean it in the middle? This is what it looked like after removing the parts. Now we take a lot of rags, a solvent for washing, you can also take gasoline and other washing liquids that wash but do not destroy the part.

We take the IAC, carefully wash it, wipe it, and blow it out. We don’t splash a lot of liquid on him, otherwise he might choke and die.

What do you need to know when replacing the IAC?

To change and install a controller that allows you to regulate idle speed, you need to pay attention to the position of the rod. It must not be allowed to be pushed forward too much. This can happen if the device is connected to the block and the ignition is activated before installation. It is not allowed to push the rod in by hand.

If the valve is installed with the needle extended and the retaining screws are tightened, damage to the unit may occur due to shearing of the worm gear. It is impossible to repair such a sensor. Depending on the vehicle model, after installing a new regulator, it may need to be calibrated. In some cars, this procedure is carried out using special equipment or a stand.

On VAZ cars, calibration is performed as follows:

1. A terminal is connected to the negative output of the battery.
2. The key is turned in the lock to turn on the ignition for ten seconds. There is no need to start the power unit.
3. The ignition is turned off.

User Ovsyuk talked about replacing the idle air valve on his own using the example of a Lada Samara car.

Calibrating a new IAC

What should I do if the test reveals that the sensor needs to be replaced? It needs to be calibrated.

1. We check the distance from the end of the rod to the mounting plate, it should be no more than 23mm.
2. We disconnect the minus from the battery, de-energizing the ECU.
3. Install the regulator.
4. We connect the battery back.
5. Turn on the ignition for 5 seconds without starting the engine. At this time, the IAC calibration occurs.
6. Turn off the ignition to complete the calibration.
7. We start the engine and observe the idle speed.

Now you know how the idle air regulator works, how to check it and, if necessary, replace it. As you understand, there is nothing complicated about this and all operations are accessible even to a novice car enthusiast.

Finally, a video about diagnosing IAC:

Previous post How to check gasoline injectors

Next entry Misfires - causes, diagnosis, elimination

Tips for extending the service life of IACs

To increase the service life of the sensor, you need to follow simple rules:

1. The air filter device must be replaced on time.
2. You cannot park your vehicle for long periods of time in winter. At low negative temperatures, the car owner must periodically start the power unit, warm it up and perform gas changes. This will allow the valve to be designed to prevent it from sticking.
3. Do not allow foreign liquids to enter the throttle mechanism area. Sprays for quick starting of the engine usually do not pose a danger to the sensor, but it is better not to overdo it.

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.

Video “Self-calibration and removal of the rod from the IAC”

User Ruslan K talked about how to remove the needle from the regulator at home and calibrate it without special equipment.

Do you have any questions? Specialists and readers of the AUTODVIG website will help you ask a question

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