Symptoms Of Bad EGR Valve And Its Causes

If you are doubtful of having a bad EGR valve, you should go through the signs of a bad EGR valve to fully understand the fact pertaining to it. Some signs of a faulty EGR also signal toward issues with other parts of the system. So before we move on to the signs, let’s look at what exactly an EGR valve is and how does it work.

What is an EGR Valve?

Exhaust Gas Recirculation, more commonly known as EGR vale is present in most diesel and gas engines. The purpose of this component is to recirculate the emissions from engine by sending them back to the combustion chamber instead of returning them to the exhaust emission system.

There have been evident changes in the climate due to pollution and related factors in recent years; EGR is one way to manage this pollution. This valve must be added to all vehicles in order to meet the regulations and standards set by the government. When there is a fault in the EGR, it leads to pollution and poor running system. It is very simple to diagnose the issue and repairs are quite easy when proper skills are being used.

Benefits of EGR Valve

The benefits of an EGR valve are as follows:

  • It reduces the number of nitrogen emissions being produced
  • Reduces the cylinder temperature significantly

How Does the EGR Work?

The engine’s intake picks up air from the environment that contains 80% nitrogen, 20% oxygen, and minor other elements. When air from outside is combined with gasoline it burns inside the combustion chamber during which temperatures increase up to 25000 F. The inert gas nitrogen is burned during combustion at such high temperatures, which results in the production of nitrogen oxides. The compound and gases produced as a result pollute the air and cause an adverse effect on human health. The EGR plays the role of returning the exhaust gases to the combustion chamber in order to lower the temperature and avoid any nitrogenous oxides from forming.

EGR is a very small part that is made to open and close as per the need to facilitate the movement of gases in and out of the combustion chamber. Irrespective of the engine system configuration this is the role of EGR. This remains the same regardless of the type of control and number of sensors, to open and send the exhaust gases back to the combustion chamber or prevent them from entering.

The valve begins to work and remains on standby as soon as the engine is started, averting the exhaust gas flow and awaiting in a closed position. When the operating temperature is attained by the engine and speed also increases, the valve opens gradually either via the pipe control or electronic control. The way for combusted exhaust gases is paved and combined with air-fuel blend in the chamber. When slowly and efficiently you come to a halt, the valve closes and the flow of gases stops. This process continues as long as the engine operates, and once the engine is shut, the valve closes and stays in a certain position.

What Are Different EGR System Types?

A range of EGR valve configurations is used by diesel- and gas-powered engines.

Old Vehicle Models:

A thick, round, and metallic EGR valve is featured in these, which has a diameter of 3 inches and is located at the upper side of the engine. A vacuum hose runs are present on these vehicles that operate the EGR valve. The upper part of EGR is connected to the carburetor, and the valve’s metal disk has a plunger, vacuum diaphragm, and spring.

Semi Modern Vehicle Models:

An electronic EGR valve is present either in a small block or cylinder, in such vehicles. It works just like those in the older models, the difference being that the EGR position sensor communicated with the vehicle computer for faster and easier control. The electric solenoids are connected through the vacuum line to the valve.

Latest Models:

An electric EGR system is used by these including additional components like the digital vale that removes the requirement of vacuum control.

Radical Design:

The EGR valve is replaced by EGR jets in other models, at the lower intake part. This is just in a few cars though, and some very efficient engines like those having variable valve timing have no need of an EGR.

What Are Different Types of EGR Valves?

  • Back-pressure EGR valve
  • Vacuum-controlled EGR valve
  • Electronic-vacuum control EGR valve
  • EGR jets
  • Digital EGR valve

What Are The Symptoms of a Bad EGR Valve

1. Poor Engine Performance:

A bad EGR valve will cause issues with your engine performance, and you may encounter issues like difficulty in acceleration, reduction in engine power when stepped on gas pedal, etc. The air to fuel ratio is out of whack that causes these problems. Hence, more fuel is needed by the engine on average to provide the engine with required power. Therefore, you will be spending more on gas due to the reduced fuel efficiency in the vehicle.

2. Engine Warning Light:

When the EGR valve fails, you will notice the ‘check engine’ light turned on. The moment it is sensed by the central computer that the valve is in an abnormal position, this light goes up. For instance, if the EGR valve fails opening or closing like it should, an issue will be detected by the computer and you will see the ‘check engine’ light turned on.

3. Fuel Smell:

The engine is consuming more fuel than it should now, more hydrocarbons will be exiting the tailpipe now. The fuel odor will then be exaggerated and you will feel it inside the car now. The smell will cause irritation as it is very bad for human health.

4. Emission Test Failed:

In case you are living in a state where you must carry out emission tests every six months, a faulty EGR valve might be observed during a failed test. You may not get a heads up for the issue during the trial, but it is definitely something to watch out for.

5. Rough Idle:

In case of a bad EGR valve, the engine will have a rough idle as the ale remains in either a closed or open position. This implies that either too many or too few of exhaust gases are coming into the chamber, causing the idling in the engine.

What Are The Reasons of a Faulty EGR Valve?

Two types of bad EGR valves exist with different symptoms for each. The three ways in which an EGR valve can be faulty are that it will either stay open, closed all the time, or will remain clogged by debris and carbon.

1. Valve Remains Open:

A vacuum leak is created if the EGR valve stays in an open position. This causes incomplete combustion resulting in rough idling or hesitation. Another symptom of an open valve can also be stalling, though it occurs in extreme situations. Oxygen from the atmosphere is needed by the vehicle to burn the carbon dioxide. If the chamber is flooded with exhaust gases, some functions of the vehicle are also affected as a result.

Diagnosing an Open EGR:

Look at the plunger shaft when the vehicle is idling while being parked, and check if it is open or closed. Error codes P1404 and P1406 are usually seen in case the valve is open. For this, remove the plug and fill carbon cleaner in it. If the fluid leaks while the lid is covered upside down, the valve helps open. For this, use a valve cleaning kit and proceed on pulling the vacuum on the vale.

2. EGR Remains Closed:

In this case, the vehicle emits large amounts of nitrogen oxide and may also knock when the fuel mixture in the chamber burns before getting the cylinder explosion. This causes disruption in the engine timing.

Diagnosing a Closed EGR:

Check if the EGR valve moves when the car revs while being parked. Error P1406 and P041 will appear when the EGR is closed, and the knocking sound acts as a sign that the valve is closed. The valve needs to be removed now in order to use the valve kit for cleaning the debris.

3. EGR Valve Clogged:

The EGR valves may be prevented by chucks of carbon from sitting as they are supposed to. This causes rough idle, and in extreme cases, the vehicle may halt. This is because there is no recirculating being done to the engine at idle by the exhaust gas, which only happens when a speed of 30mph is exceeded by the vehicle.

Diagnosing a clogged EGR:

Error code P1406 and P1404 will show up in case of a blocked EGR. For this, remove the plug and use a valve cleaning kit to remove any blockages. If this can not be checked on your own, get some assistance from a professional.

In Conclusion

Signs of a faulty EGR often reflect other issues in the engine that cause confusion. Fortunately, you are aware of the symptoms of a bad EGR valve now and can also easily fix it. Keep from switching components in the attempt of fixing the issue before you are very sure about the exact issue. In case you face any difficulty in fixing the problem, contact a mechanic to get professional assistance.