How to diagnose EGR valve

 What is an EGR actually?

The exhaust gas recirculation valve, or EGR valve for short, is a crucial component of the car's engine management system and recirculates precisely measured amounts of exhaust gas to the engine intake system for improved engine efficiency, lower fuel consumption, and lower NOx emissions.

The EGR valve will become more crucial going forward due to rising pressure to cut emissions. Knowing what it does, why it fails, and how to replace it when it does is crucial.

Basic an EGR system

What functions an EGR valve?

Nitrogen makes up around 80% of the air we breathe. The typically inert gas becomes reactive when subjected to the combustion chamber's extraordinarily high temperatures, plus 1370°C, and produces damaging nitrogen oxides, or NOx, which are then released into the atmosphere via the exhaust system.

The EGR valve permits a precise amount of exhaust gas to re-enter the intake system, effectively altering the chemical composition of the air entering the engine, to assist reduce this. With less oxygen present, the mixture burns more slowly, lowering combustion chamber temperatures by over 150°C and cutting NOx production for a cleaner, more effective exhaust.

The EGR valve can be in any position between its two basic positions of open and closed. When the engine starts, the EGR valve is shut. The valve progressively opens at idle and at low speeds since these conditions call for little power and, consequently, little oxygen. At idling, the valve may be up to 90% open. However, the EGR valve closes to guarantee that as much oxygen enters the cylinder as possible when greater torque and power are needed, such as during full acceleration.

EGR valves can be employed in downsizing GDi engines in addition to decreasing NOx to lower pumping losses and increase combustion efficiency and knock tolerance. Diesel knock at idle can also be lessened in diesel engines.

Why does the EGR valve fail?

EGR valves operate in a harsh environment, thus they will gradually deteriorate. The accumulation of carbon particles from exhaust gases throughout the EGR and intake system passageways, however, is the single main cause of failure. This will eventually block the valve's plunger mechanism, causing it to stick open or close, as well as the tubes and exhaust gas channels. A rupture or leak in the valve diaphragm can also be the cause of failures.

EGR valve filled with carbon

What to check out for in an EGR valve that is failing?

EGR problems continue to be a pain for many technicians since the indications of EGR valve failure are similar to those of many other engine management components. But there are a few warning signals to watch out for:

• Check engine light: similar to the majority of engine management parts, the EGR valve may cause the check engine light to come on.

• Engine performance problems: If the valve is jammed open, the vehicle's air-fuel ratio will be disturbed, leading to problems with the engine's power, acceleration, and idling. Additionally, it can result in turbo boost pressure leaks, which would make the turbo work harder.

• Increased NOx emissions: When the EGR valve is left closed, the combustion chamber will reach high temperatures and leave a lot of fuel unburned, which will result in increased NOx emissions and decreased fuel economy.

• Engine knock: Because of the greater temperatures and NOx, there may be more detonation or knock, which is audible as engine banging.

For more information and to better understand...Let's watch this video!!!