EGR valve wear - change or “muffle”

The air that enters the engine is mostly nitrogen. To ensure the most complete combustion of fuel (hydrocarbon) in the cylinders, it is necessary to increase the temperature. But here an ecological “hitch” appears - at 2000 ° nitrogen is oxidized, forming harmful compounds that fly straight into the exhaust manifold. And, if the catalyst copes well with carbon oxides, then it has “problems” with NO. They are solved by the exhaust gas recirculation system - Exhaust Gas Recirculation.

How EGR works in theory

The goal is to partially feed the exhaust gas back into the intake manifold. What does it give? When nitrogen compounds enter the fuel mixture, the amount of oxygen in it decreases. This leads to a drop in combustion temperature. As a result, less nitrogen oxides are formed, as well as harmful emissions from the muffler.


The only task of EGR is to improve the environmental situation in the atmosphere; this system does not affect anything else.

Practical action of recycling

The main element is a valve integrated into the intake manifold and opens / closes at a certain moment during the operation of the internal combustion engine. This technical solution reduces nitrogen oxide emissions by about half. True, there are also side, albeit minor, but pluses. The ingress of exhaust gases into the collector reduces the vacuum, which helps to reduce fuel consumption by 2-3%. Other positive aspects include reducing the risk of detonation to zero. Well, even the amount of soot on the exhaust of diesel units drops by 10%. That's all the "side" pluses of EGR.

Valve operation algorithm

On gasoline internal combustion engines, it operates exclusively at medium speeds, "diluting" the air with exhaust gases by 5-10%. Diesel engines are a different matter: in them, the system already works at idle, and as they increase, it gradually ceases to let exhaust into the manifold.


There is no recirculation system on turbocharged gasoline units. Why? Even on “atmospherics” the valve works at medium speeds, and on supercharged internal combustion engines, the range is even narrower. I must say: this part is expensive and its installation on turbocharged engines will simply give a minimal result. Here, the reduction of NO emissions is carried out by other methods. For example, they use an intercooler (inlet air cooling) or a stepless phase change in the timing. We are talking about internal recirculation, when the exhaust is again in the cylinder, when the intake and exhaust valves are open.

EGR types

The principle of operation is the same for them, the only difference is in the main part.


The valve can be of several varieties, depending on the type of internal combustion engine, design.

Pneumomechanical

An old version, tested on American cars in the 70s. Today it is quite rare. In the closed position, the valve is fixed by means of a steel spring. When a vacuum is formed (it appears at medium loads), the membrane presses on it and the device opens.

Electro-pneumatic

Here the controller commands, taking into account the signals of one of the sensors, for example:

✅ oxygen (stands on the outlet)
✅ recirculation valve positions
✅ DMRV

But other alerts may also be involved. Upon receiving a signal from them, the ECU activates the actuator and the valve opens / closes.


The most advanced electro-pneumatic devices very smoothly regulate the EGR process, for which a vacuum pump can be used.

Digital EGR valves

They are divided into two main types: with a pair or three different holes closed by solenoids. As a result, several degrees of recirculation can be obtained. If 3 holes are used - 7 combinations, 2 - three options. The most perfect is the valve, which is paired with a stepper motor. Such a system guarantees a very smooth opening of the device.


And if the EGR valve is also included in the automotive cooling system, nitrogen oxide emissions will drop even more.

Recirculation faults

The most common of them is the deposition of carbon deposits on the plane of the valve. This is usually due to low fuel quality, regular trips over short distances. If the engine is not in the best condition, it is very worn out, the process of coating the valve with deposits is accelerated many times over. The appearance of soot is fraught with further violations in the EGR system.

Jamming

Deposits prevent the rod from moving, and it stops in one position. The result may be a "swimming" of idle speed, stopping the internal combustion engine. Also, a malfunction of the valve is indicated by “shooting” into the muffler, a difficult start of the engine, and a decrease in acceleration dynamics. Sometimes the valve burns out, which is tantamount to jamming it open. The question is how the ECU reacts to it. Sometimes it can put the engine into emergency mode.


All of the problems described above are specific to pneumatic valves. Digital (electronic) coking is not so much affected. But they serve, oddly enough, less. This happens due to the presence of moving elements in the device. Soot clogs the gaps and the part has to be changed: it cannot be replaced.

Is the valve always to blame?

No, so do not rush to buy a new one. The case may be in non-working sensors that "cooperate" with the EGR, a malfunction of the vacuum system. Even air leaks and a pipe with cracks will also "make their contribution." The reason is often banal and is an excessively worn internal combustion engine.

Buy a new one or "jam"?

The service life of recirculation valves is 70-100 thousand km. However, in practice, in difficult conditions, the resource drops to 50 thousand km. There are few people who want to buy a new expensive part: most of them “muffle” the valve by installing a gasket without holes.


And if this gives some result on gasoline "atmospherics", then problems may appear on turbocharged diesel engines. For example: the impossibility of controlling the boost, which leads to premature wear of the turbine. There is also a common minus: with the recirculation valve constantly open, the waste generated during the combustion of the mixture will fly straight into the cylinders.


And if the valve is digital, you will need to flash the ECU. But all this is relative: there are pluses.

The positive side of the removal (silencing) of the EGR valve

When it works, exhaust gases partially enter the cylinders, saturated with soot, tar and other microparticles, which contribute to a decrease in engine life. In addition, the exhaust supply oxidizes the oil faster, which will require replacement. a slight increase in ICE power is also possible.

Prevention

However, it is worth listening to the arguments of logic: if the EGR is installed from the factory, then it’s not just that, and all this has been tested and tested a thousand times. A similar "theory" is followed by many car owners: the less you climb into the factory settings, the better. And then what to do to make the valve last longer? As mentioned above, electronic products require replacement. But pneumatic devices must be regularly freed (rod and seat) from soot with an aerosol to clean the carburetor.


In the process, try not to let the chemical get on the rubber elements of the product. An EGR with an electro-pneumatic device usually has a filter that needs to be cleaned periodically.

The main preventive rule is the timely maintenance of the engine, the replacement of "consumables". Then the resource of the EGR valve will increase to 150 thousand kilometers or more.