Stopped the egr valve. What is the USR valve and is it worth turning it off? What to do if the EGR valve is out of order

The EGR system has been installed on vehicles since the mid-70s. It was at this time that manufacturers began to pay special attention to the requirements for environmental friendliness of the car.

The functioning of the EGR system is similar to the fact that a person re-inhales part of the exhaled air. Air pollution naturally decreases. But breathing is also difficult. Photo: auto-volgograd.com

Why you need an EGR system

The principle of operation of the USR system is based on a scheme when part of the exhaust gases again enters the inlet manifold. This allows:

reduce the level of nitrogen oxide in the exhaust;
introduce an additional level of control over the toxicity of waste combustion products;
reduce engine detonation;
to increase the completeness of fuel combustion;
accelerate the heating of the input path.

Modern control units for internal combustion engines vigilantly monitor the performance of the USR, as one of the systems that ensure the environmental properties of a car. If EGR is disabled or disabled, the control unit is able to choke the engine at high revs, speeds and increased load. To eliminate this problem, chip specialists use special software, reflashing the microprocessor of the control unit.

Design features

The first USR system delivered to Chrysler in 1971 was not equipped with a valve. She worked constantly, even at low revs and starting the engine, which significantly deteriorated the engine parameters. For the first time, Buick makers included a pneumatic valve in the system, which provided control of the moment the recirculation system was turned on according to the manifold vacuum pressure. This design turned out to be successful, pneumatic valves are installed on some cars to this day.

This is what the main types of EGR valves look like. Photo: etlib.ru

The electromagnetic (aka digital) valve, used on most modern cars, has significant advantages over pneumatic:

the valve activation control process can be organized based on the readings of a large number of sensors (vehicle speed, crankshaft, throttle valve, differential pressure at the outlet / input of the USR, lambda probe, flow meter and others), increasing the accuracy of parameter control;
an electric valve is more reliable than a pneumatic system;
regulation of the gas bypass channel can be carried out smoothly in a pulse or analog mode;
no air tube installation required.

The electro-pneumatic EGR valve system can be installed on engines that are controlled by two or more recirculation channels.

Structurally, gas outlet and valve parts are made of high-alloy steel, capable of withstanding high temperature loads of exhaust gases. With a worn piston group, the valve becomes contaminated with oil combustion products over time, starts to work incorrectly, and may fail.

The principle of operation of the USR system

The main purpose of EGR is to reduce the percentage of nitrogen oxide in the exhaust gas. Nitric oxide is formed at elevated combustion temperatures. The temperature can be reduced by lowering the oxygen concentration in the incoming mixture. By opening the recirculation channel, the EGR valve lets in exhaust gases, in which there is practically no oxygen. The ignition temperature decreases, the concentration of toxic oxide decreases.

A decrease in temperature leads to a decrease in the efficiency of the internal combustion engine, its power. This is a tribute to the requirements of the environment.

In diesel engines, the amount of recirculated gases reaches 30-50%, the valve opens at idle speed, and closes when the internal combustion engine warms up. In gasoline models, the EGR valve closes under increased load. The amount of recirculated gases usually does not exceed 10 percent of the basic composition.

Self-deactivation of the EGR valve

Automatic shutdown of EGR is performed in the following cases:

severe wear of the piston group of the internal combustion engine in cars with high mileage to prevent oil combustion waste from entering the intake manifold, contamination of spark plugs, and an increase in smoke;
chipping in the process of forcing the internal combustion engine;
refueling with bad fuel, dirty channels;
incorrect EGR algorithm.

In a car after 2010, blocking the USR system by the user leads to the fact that the control system begins to forcibly "choke" the engine in order to reduce the concentration of toxic emissions. This is felt by the driver at increased revs and loads, high speeds. Experienced chip makers, forcibly disabling the USR system, reprogram the control unit operation algorithm, the fuel card.

Should you turn off the EGR valve? Reflections on this topic can be found in the video:

Causes of EGR valve malfunction

The reasons for the malfunction may be:

low-quality fuel;
malfunction of injectors;
incorrect ignition angle adjustment;
ICE wear, low compression;
exceeded oil level;
problems with electrical equipment;
improper operation of ICE control devices;
mechanical wear of the EGR valve.

Usually, problems with the EGR valve begin after 100,000 kilometers, when using low-quality gasoline - after 30-40 thousand km.

Malfunction symptoms

The main signs of incorrect operation of the USR system:

Valve clogging increases its response time, can lead to seizure, which in turn leads to an increase in fuel consumption.
A permanently open valve will reduce the rated power of the engine and cause starting problems.

Valve breakage is accompanied by the following symptoms:

unstable idle speed;
detonation when stopping the internal combustion engine;
changing the dynamic characteristics of a car;
increased smokiness;
increased noise of the engine running.

Control of serviceability of the EGR valve

In cars before 2005, the valve malfunction may not appear in any way, even by indication of the "CHECK ENGINE" warning light. Therefore, periodically (preferably before the start of the next season of operation) it is recommended:

visually check the integrity of the wiring to the valve, pipes, fasteners, electrical connectors;
measure the resistance of the solenoid valve winding (should be in the range from 15 to 200 ohms);
do computer diagnostics of the internal combustion engine.

EGR valve repair and replacement

The EGR valve is usually located in an easily accessible part of the engine compartment from the bumper. Its dismantling and installation usually does not cause problems.

In the event that the winding of the solenoid valve is out of order, it must be replaced. If the winding is intact, the problem is severe contamination of the channels, you can clean the EGR valve. At a service station, this procedure costs from 1000 rubles. You can save time and money by cleaning the EGR valve yourself.

The first stage of valve cleaning is the immersion of the recirculation and valve channels in a special flushing composition (time from 1 hour to a day, depending on the degree of contamination). As such a composition, you can use a non-aggressive solvent, in extreme cases, acetone.

The most suitable option is a carburetor cleaner. It is better to protect the electromagnetic part (coil) of the valve from the ingress of cleaning liquid: this can lead to its destruction.

The second stage consists in purging and further flushing of the recirculation channels using a syringe or medical enema. It is better to open the solenoid valve by forcibly applying voltage to it from the battery. The pneumatic valve can be opened by applying a vacuum to the pneumatic port.

When installing a new or refurbished valve, you should:

use high temperature sealant;
install only a new gasket;
observe lingering threading forces;
control the tightness of the tubes.

The EGR valve replacement option is presented here:

Outcome

Some car owners do not pay due attention to the operability of the USR system, considering it insignificant. However, with the correct operation of the EGR valve, the engine runs smoother and wears out less. Environmental performance is noticeably improving, this is so important in our time.

During the operation of a diesel engine with an EGR system, especially after a run of several tens of thousands of kilometers, owners often complain about a decrease in the power of the power unit and smoke from the diesel engine. There is also a widespread belief among tuning enthusiasts that the exhaust gas recirculation system "chokes" the engine, preventing the power unit from fully realizing the power output. For this reason, many drivers decide to shut off the EGR valve.

In other words, the EGR valve plug is actually a shutdown of the exhaust gas recirculation system, which eliminates possible problems with this solution and add power to the engine. Next, we will take a closer look at why the exhaust gas recirculation system is muffled, as well as where to muffle the EGR valve on a diesel engine and how to do it correctly. The Exhaust Gas Recirculation (EGR) system is a solution that reduces the level of nitrogen oxides in the exhaust gases of a gasoline or diesel engine. This system as applied to modern internal combustion engines is absent only on gasoline turbo engines. Diesel engines have different exhaust emission standards. For this reason, EGR in a diesel engine can be implemented in different ways.

The main function of the EGR system is to partially return the exhaust gases back to the engine intake manifold for afterburning. The USR of a diesel engine makes the operation of engines of this type softer and smoother, gasoline units with EGR suffer less from detonation. The exhaust gas recirculation system is able to improve the performance of a diesel or gasoline internal combustion engine and reduce fuel consumption. The engine exhaust from the USR becomes less toxic.

Why turn off the EGR valve

To begin with, the EGR system is installed on a diesel engine to comply with the stringent environmental regulations and standards that apply in developed countries. EGR is primarily intended to reduce the level of nitrogen oxides in engine exhaust gases. The system partially redirects the exhaust gases back to the intake manifold, due to which the amount of oxygen in the fuel-air mixture is reduced, the formation of nitrogen oxides becomes less intense and the toxicity of the exhaust is within the specified standards. The EGR valve opens at the right time, allowing a portion of the total exhaust gas to flow back into the intake to be fed into the engine cylinders. As practice shows, the EGR valve is often clogged during operation. The need to muffle the EGR arises due to the fact that soot and other exhaust components quickly disable the specified element, the clogged system prevents the supply of clean air for the most efficient combustion of diesel fuel. On high-quality European diesel fuel, cleaning the EGR valve may be required once every 40 or even 60 thousand km. Driving on domestic diesel fuel makes the specified procedure to be performed every 20-30 thousand km. Moreover, the relevance of equipping the engine with such a system is questioned by many experts. Disabling the USR naturally leads to an increase in the level of emissions of nitrogen oxides. In parallel with this, emissions of soot, carbon dioxide and carbon monoxide are significantly reduced. Also, after disabling the USR system, fuel consumption decreases, since the amount of oxygen in the intake increases and the mixture burns more efficiently in the cylinders. In other words, the usefulness of such an exhaust recirculation system is questionable. Environmental performance improves marginally compared to loss of engine power, increased fuel consumption and EGR service costs. There are also separate statements that the rapid contamination of the EGR valve and the supply of exhaust to the intake lead to increased carbon formation and coking of the combustion chamber. Malfunctions of the EGR system, which are often associated with incorrect operation of the EGR valve, lead to unstable engine operation and increased fuel consumption. Soot and tar gets into the engine, the process of accelerated oxidation of diesel engine oil takes place, which greatly affects the overall service life of a diesel engine. The need to turn off the USR system often arises on runs of about 80-120 thousand km. The fact is that after such a run, the engine wears out a little. The exhaust gases that are redirected to the intake have a higher degree of contamination. Further, they are mixed with crankcase gases, and the result is the appearance of a thick layer of tarry deposits in the intake manifold, on the Egr valve, and also on the valves of the engine itself. The intake flow area becomes clogged with deposits, the diesel engine gradually loses power. A clogged EGR valve leads to errors, the car may suddenly go into emergency mode. It is quite obvious that in such a situation it is necessary to urgently repair the exhaust gas recirculation system or to turn it off by muffling the EGR valve.

How to muffle the USR valve with your own hands

To begin with, the correct shutdown of the EGR system involves:➤ mechanical damping of the valve; ➤ software shutdown in the control unit; At the initial stage, a mechanical plug of the USR valve is installed. Further, the shutdown of the EGR system is carried out using electronic equipment. It should be added that only on some models it is enough to physically muffle the Ugr valve. Often, after the mechanical shutdown procedure, software shutdown of the EGR valve in the control unit is additionally required. Otherwise, the ECU will record an error in the operation of the exhaust gas recirculation system, “check” is displayed on the instrument panel, the engine goes into emergency mode with limited power output. In general terms, the most simplified version of the EGR valve plug installation assumes: 1. Removing the valve. The specified element is most often located in the area of the intake manifold and is fastened with several bolts. 2. If necessary, the intake manifold is additionally removed and the intake manifold channels are cleaned from dirt. 3. Next, you need to remove the gasket, which is located at the place where the valve is attached. 4. After removal, the gasket plays the role of a template, according to which it is necessary to cut out from the steel sheet a similar in shape, but completely blind stub gasket. The plug will only have holes for the fastening bolts.

Please note that the plug will come into contact with hot exhaust gases under pressure during operation. For this reason, it is necessary to make a gasket of the appropriate thickness in order to exclude the possibility of its rapid burnout. We add that the ready-made plug of the EGR valve is also available on the free market. To order a solution suitable for a specific model, you can use the search on specialized automotive forums.

5. The next step is the reverse installation of the Egr valve. At the attachment point, a standard gasket and a new plug are combined. Be careful when retightening the bolts as they may be fragile. 6. At the end, it is necessary to realize the disconnection of the vacuum hoses, since it is no longer necessary to open the valve by means of the vacuum system. 7. The final step in the recirculation shutdown procedure is to make adjustments to the firmware of the engine control unit in order to programmatically disable the EGR error.

Advantages and disadvantages of turning off the USR

The only drawback of removing the USR can be considered an increase in the toxicity of exhaust gases. There are many more advantages. After plugging the EGR valve on a diesel engine, the owners note a sharper response to pressing the gas pedal at moderate loads, the so-called turbo lag effect on turbodiesels becomes less noticeable. During operation under load, the engine emits less smoke, the service life of the particulate filter increases, and the intervals between cleaning it increase. The service life of the engine oil is also extended, the engine is better cleaned, less prone to coking and wear.

It should be noted that although a noticeable increase in the power of the diesel engine does not occur after disabling the USR system, the engine becomes more responsive, and the car itself feels more dynamic when driving.

Finally, we add that if a decision is made to make a power chip tuning of a diesel engine or to install a tuning box on a diesel engine, then disabling the exhaust gas recirculation system is an extremely recommended procedure.

For starters, the EGR system is installed on a diesel engine to meet the stringent environmental regulations and standards that apply in developed countries. EGR is primarily intended to reduce the level of nitrogen oxides in engine exhaust gases.

The system partially redirects the exhaust gases back to the intake manifold, due to which the amount of oxygen in the fuel-air mixture is reduced, the formation of nitrogen oxides becomes less intense and the toxicity of the exhaust is within the specified standards.

The EGR valve opens at the right time, allowing a portion of the total exhaust gas to flow back into the intake to be fed into the engine cylinders. As practice shows, the EGR valve is often clogged during operation. The need to muffle the EGR arises due to the fact that soot and other exhaust components quickly disable the specified element, the clogged system prevents the supply of clean air for the most efficient combustion.

On high-quality European diesel fuel, cleaning the EGR valve may be required once every 40 or even 60 thousand km. Driving on domestic diesel fuel makes the specified procedure to be performed every 20-30 thousand km.

Moreover, the relevance of equipping the engine with such a system is questioned by many experts. Disabling the USR naturally leads to an increase in the level of emissions of nitrogen oxides. In parallel with this, emissions of soot, carbon dioxide and carbon monoxide are significantly reduced. Also, after disabling the USR system, fuel consumption decreases, since the amount of oxygen in the intake increases and the mixture burns more efficiently in the cylinders.

In other words, the usefulness of such an exhaust recirculation system is questionable. Environmental performance improves marginally compared to loss of engine power, increased fuel consumption and EGR service costs.

There are also separate statements that the rapid contamination of the EGR valve and the supply of exhaust to the intake lead to increased carbon formation and. Malfunctions of the EGR system, which are often associated with incorrect operation of the EGR valve, lead to unstable engine operation and increased fuel consumption. Soot and tar gets into the motor, an accelerated process takes place, which greatly affects the overall one.

The need to turn off the USR system often arises on runs of about 80-120 thousand km. The fact is that after such a run, the engine wears out a little. The exhaust gases that are redirected to the intake have a higher degree of contamination. Further, they are mixed with crankcase gases, and the result is the appearance of a thick layer of tarry deposits in the intake manifold, on the EGR valve, and also on the engine itself.

The intake flow area becomes clogged with deposits, the diesel engine gradually loses power. A clogged EGR valve leads to errors, the car may suddenly go into emergency mode. It is quite obvious that in such a situation it is necessary to urgently repair the exhaust gas recirculation system or to turn it off by muffling the EGR valve.

How to muffle the USR valve with your own hands

To begin with, the correct shutdown of the EGR system involves:

mechanical damping of the valve;
software shutdown in the control unit;

At the initial stage, a mechanical plug of the USR valve is installed. Further, the shutdown of the EGR system is carried out using electronic equipment. It should be added that only on some models it is enough to physically muffle the Ugr valve. Often, after the mechanical shutdown procedure, software shutdown of the EGR valve in the control unit is additionally required. Otherwise, it will record an error in the operation of the exhaust gas recirculation system, “check” is displayed on the instrument panel, the engine goes into emergency mode with limited power output.

In general terms, the most simplified version of the EGR valve plug installation assumes:

Removing the valve. The specified element is most often located in the area of the intake manifold and is fastened with several bolts.
If necessary, the intake manifold is additionally removed and the intake manifold channels are cleaned from dirt.
Next, you need to remove the gasket, which is located at the place where the valve is attached.
After removal, the gasket plays the role of a template, according to which it is necessary to cut out from the steel sheet a similar in shape, but completely blind stub gasket. The plug will only have holes for the fastening bolts.
Please note that the plug will come into contact with hot exhaust gases under pressure during operation. For this reason, it is necessary to make a gasket of the appropriate thickness in order to exclude the possibility of its rapid burnout. We add that the ready-made plug of the EGR valve is also available on the free market. To order a solution suitable for a specific model, you can use the search on specialized automotive forums.
The next step is the reverse installation of the Egr valve. At the attachment point, a standard gasket and a new plug are combined. Be careful when retightening the bolts as they may be fragile.
At the end, it is necessary to realize the disconnection of the vacuum hoses, since it is no longer necessary to open the valve by means of the vacuum system.
The final step in the recirculation shutdown procedure is to make adjustments to the firmware of the engine control unit in order to programmatically disable the EGR error.

Advantages and disadvantages of turning off the USR

The only drawback of removing the USR can be considered an increase in the toxicity of exhaust gases. There are many more advantages. After plugging the EGR valve on a diesel engine, the owners note a sharper response to pressing the gas pedal in moderate load modes, the so-called turbodiesel becomes less noticeable. During operation under load, the engine emits less smoke, the service life of the particulate filter increases, and the intervals between cleaning it increase. The service life of the engine oil is also extended, the engine is better cleaned, less prone to coking and wear.

Finally, we add that if a decision is made to make a power one or to make an installation, then turning off the exhaust gas recirculation system is an extremely recommended procedure.

What do we want to achieve?

It would seem that the exhaust system of a car is the simplest part of its design, and nothing can be improved here. But recently, a lot of "improvements" have appeared, allowing either to increase the operational parameters of the internal combustion engine, or to reduce the toxicity of the exhaust. The use of direct-flow mufflers, as well as active noise suppression systems - all this is necessary for the car owner, but not for the environment. But catalysts, sometimes used in conjunction with intercoolers, or systems of the "EGR" class, are already inventions pleasing to environmentalists. It is easy to see that the environmental friendliness of an engine cannot be improved without lowering its power, torque, etc.

When we start a cold engine, the EGR valve remains closed, and exhaust gases cannot enter the intake manifold. As soon as the coolant temperature exceeds 80-90 C, this valve can be opened under certain conditions. The following tuning method is known: the exhaust gas flow to the EGR valve can be shut off, for which a plug is installed. Such tuning has easily predictable consequences:

The engine runs at full strength all the time (good);
The maximum combustion temperature rises (bad);
Inside the cylinders there will be only a mixture of fuel and clean air (also good);
The catalysts will quickly fail (very bad!).

Based on the above estimates, it will be necessary to decide whether it makes sense to carry out the revision we are considering. It is clear that after its completion, the engine will be removed from the warranty, so we will leave the choice to the owner. First you need to make sure that the EGR system in the power unit really has a presence: it is used in conjunction with GDI engines, as well as with TDI "diesels". But the same cannot be said about turbocharged gasoline engines.

Tuning methods

Depending on the design of the engine as a whole, more precisely, on the design of the EGR system, different methods of closing the exhaust return flow channel are used. You can unscrew the pipe that supplies the exhaust gases to the EGR valve and install a plug (a circle made of thin PCB) over the rubber washer. In Japanese cars, the pipe is usually made of a copper alloy, and it is screwed to the valve body with a nut. Pay attention to the photo on the left, and everything will become clear.

GM vehicles use a two-piece EGR valve (see first picture). The top of this structure is attached to the bottom with two metric bolts. Having unscrewed them, you can see a metal gasket, one of the holes of which must be closed. In general, you can make a similar can gasket, but one that does not have the strikethrough hole. As you can see, nothing complicated. Some people recommend making the specified part from sheet chrome-plated brass.

EGR (abbreviation for Exhaust Gas Recirculation) is an exhaust gas recirculation system. According to EGR technology, some of the exhaust gases are returned to the air intake system to form a combustible mixture.

The system does not improve the performance of internal combustion engines, rather the opposite. EGR installation in vehicles is intended for:

reducing the toxicity of exhaust gases, primarily the level of nitrogen oxide in exhaust gases;
introduction of an additional degree of environmental control of the vehicle;
reduction of detonation processes;
more complete combustion of fuel;
fast warming up of the inlet air duct.

In cars of the last years of production, EGR failure can block the correct operation of engines at high revs and speeds. There is special software that reprograms the engine control unit.

EGR valve - what is it and why is it needed

The temperature of the exhaust gases is very high, therefore, for reliable operation, it is made of durable high-alloy steel that can withstand temperature loads up to 2000 degrees Celsius. However, such steel does not have sufficient strength, especially at high temperatures. Therefore, the EGR valve does not have a high service life.

Principle of operation

Reducing the concentration of nitrogen oxide in the exhaust gases of internal combustion engines is achieved by artificially lowering the oxygen content in the input mixture. This is achieved with the help of an EGR valve, which bypasses part of the exhaust gases, in which almost all of the oxygen has already been burned out during the ignition of the working mixture, into the inlet air duct.

Thus, the oxygen concentration in the inlet circuit decreases, the combustion of the air-fuel mixture occurs at lower temperatures, and toxic nitrogen oxide is formed with a lower intensity.

Of course, this reduces the efficiency of the engine, its power, but these are the severe requirements for the environmental friendliness of vehicle operation.

If the EGR valve for some reason does not work or is deliberately blocked, the engine control unit (especially the release after 2010) gives a command to limit the supply of the fuel-air mixture, that is, artificially "chokes" the engine.

Video - about the EGR system:

The blocking of the exhaust gas recirculation system is done in the following cases:

excessive wear of the piston group, the presence of oil in the exhaust gases in order to prevent contamination of spark plugs and ignition failures;
forcing the engine, chipping;
refueling with low-quality fuel, leading to premature contamination of the valve;
violation of the algorithm of the EGR system.

Exhaust gas recirculation classification

In modern cars, three types of EGR algorithm implementation are used:

Electronic

Installed on most vehicles after 2010. The control comes from the engine control unit by means of pulses supplied to the stepper motor of the multistage device. Such a valve works not only in the "open-closed" positions, but is able to partially open the recirculation path, which increases the accuracy of the system.

Pneumatic

It is controlled by a vacuum valve that controls the pressure in the intake system.

Electro-pneumatic

This system is used when multiple valves are required to be controlled.

The control algorithm for the EGR valve (s) can be organized based on the readings of the following sensors:

exhaust gas pressure sensor;
EGR sensor;
gas temperature sensor;
vehicle speed sensor;
differential pressure sensor at the outlet and inlet of the EGR valve;
flow meter;

It is not a fact that the readings of all of the above sensors will participate in the EGR valve control process. Each manufacturer independently develops an algorithm for the operation of the system. But in all cases it is rather complicated.

In diesel engines, the EGR valve is usually triggered to open at idle speed. The amount of the by-passed waste mixture can reach 40 - 50%. As the engine warms up, it closes.

In gasoline engines, the valve closes when the engine is idling and, conversely, when the load is increased. The recycling rate is usually around 10%.

Causes of malfunction

The main causes of EGR malfunction are:

low-quality fuel, leading to the formation of excessive carbon deposits, can damage the valve after 10,000 - 20,000 km;
problems with setting the angle of ignition of an internal combustion engine;
worn valve stem seals, reduced compression, other engine problems associated with the presence of oil in the exhaust gases;
malfunction of electrical equipment;
violation of the signal processing algorithm by the engine control unit;
increased oil level;
wear of injectors;
natural mechanical wear of the valve, which usually occurs after 60 - 80 thousand km of car mileage.

Signs of a malfunction of the EGR valve

The main signs of malfunction and failure of operability are as follows:

Clogged valve can lead to seizure during operation, as well as an increase in response time. Jamming contributes to reduced engine power, erratic idle speed, black smoke in diesel engines. Untimely closing of the valve contributes to more "hard" work, increased fuel consumption.
Permanently open valve USR leads to a noticeable decrease in power and, as a result, to a decrease in its throttle response.
Valve failure leads to a complex malfunction of the EGR system, which is usually indicated by the "CHECK ENGINE" indicator on the dashboard and possible symptoms:

unstable idle speed;
increased smokiness;
decrease / increase in power;
increased engine noise;
detonation.

In cars with high mileage before the year 2000, the failure of such a valve may not manifest itself in any way, therefore, periodic (preferably before the next autumn / winter and spring / summer seasons), as well as before undergoing a technical inspection, it is recommended:

make an external examination of the wiring, connectors, pipes leading to the EGR valve;
check ("ring") the coil of the USR solenoid valve;
carry out computer diagnostics of the engine control unit.

Video - about the signs of a malfunction of the EGR valve:

Computer diagnostics of the ECM usually monitors the following parameters of the EGR system:

recirculation coefficient;
duty cycle of PWM (pulse-width modulation) pulses, if this type of EGR valve control is used;
the on / off state of the valve during normal impulse control.

Replacing or cleaning the EGR valve

It is usually located on the left side of the engine compartment or on the engine compartment bulkhead. It can be easily found by the two hoses and the electrical connector connected to the valve (in the case of a solenoid valve).

Video - how to clean the EGR valve on a Honda Fit:

Its assembly and disassembly during replacement or cleaning usually does not cause technical problems. In this case, the following requirements must be met:

apply high-temperature sealant to the threaded connection of the thermal valve;
use a new gasket during installation;
to prevent leaks, observe the tightening forces of the threaded connections (specified in the repair instructions);
check the tightness of the connection of the vacuum tubes, the correctness of the connection.

Removing it (stub)

Many car owners (especially aged vehicles) turn off the EGR system. This happens when:

the USR valve is out of order and the car owner does not want to spend extra money on its purchase;
the piston group is badly worn out, burnt oil gets into the exhaust gases, a strong carbon deposit is formed, which, in the case of recirculation, greatly contaminates the working volume of the engine and spark plugs, increases the smoke;
sometimes removing the USR valve temporarily restores idle speed and throttle response of the engine that has gone a bit too far.

For cars up to the year 2000, when removing the USR valve, it is enough to disconnect its electrical connector. In some cases, in this case, then it is better to muffle the pipes leading to the valve. This will not cause a malfunction in the vehicle's electrical equipment.

In the event that the control winding in the solenoid valve is out of order, it is possible to turn on a conventional relay or an internal incandescent light bulb in parallel with the valve for emulation, so that the engine error does not light up.

Video - is it worth turning off (muffling) EGR:

If the EGR system is turned off in cars after 2005, there may be big problems associated with the electrics.

Basically, the USR system is turned off in the process of improving the dynamic characteristics of the engine, called "chipping". What is exhaust gas recirculation? It is similar to the fact that you will again run the exhaled air into your lungs. Yes, of course, the level of harmful exhaled substances will be less, but it will also become more difficult and unpleasant to breathe. This is how many motorists reason, and not without reason.

Video - how to properly muffle the EGR valve on a VAG:

There are many service stations that provide software EGR shutdown services. Then it is possible not to make any mechanical and electrical changes in the engine control system. You just need to reflash the control unit software.

Video - about EGR and particulate filter:

Some car enthusiasts, who have, are making attempts to self-reprogram to remove EGR, using firmware and programs posted on the Internet. It is very risky, it is better to turn to professionals.