EGR delete/ pros, cons and methods of EGR removal

What is an EGR System?

The EGR system is one of several systems designed to reduce emission and soot levels, especially in diesel engines.

Like all similar systems (such as DPF and AdBlue), the EGR also has advantages and disadvantages, which has led to a market for modifying EGR maps, EGR removal, or replacing the EGR valve with other kits.

In line with these descriptions, EGR solution files or EGR delete refers to removing the EGR system through ECU tuning (software), which we will provide a complete explanation of later in this article.

EGR Valve

How does EGR work?

Approximately 80% of the air we breathe is composed of nitrogen, which is normally a relatively inert gas. However, this inert gas becomes reactive when exposed to temperatures exceeding 1370 degrees Celsius, producing harmful nitrogen oxides, known as NOx, which are easily released into the surrounding air through the exhaust system.

By adjusting the amount of oxygen entering the engine's intake air, the combustion chamber temperature can be reduced by about 150 degrees Celsius, resulting in less NOx and cleaner exhaust gas with lower pollution levels.

With the help of the EGR valve, which is present in all types of EGR systems, a portion of the exhaust gases is recirculated back to the intake manifold. This is the core principle of the EGR system.

As a result, the final combustion temperature is reduced, leading to lower emissions released into the surrounding air.

To monitor the real-time position of the EGR valve, a potentiometer integrated within the EGR valve assembly is used. This sensor can determine the EGR valve position by generating a voltage feedback signal. If the ECM's position command does not match the position feedback, an error code will be generated in the system.

Parts of EGR System

Regardless of the model of your vehicle's EGR system, all types of EGR systems have parts that are common across most versions and are essential for the proper functioning of the system. We will now examine the main components of the EGR system.

EGR Valve: One of the main components of the EGR system is the EGR valve. The EGR valve collects a portion of the exhaust gases and returns them to the engine's air intake (recycling) to reduce pollution and NOx. The EGR valve is mounted on a channel between the exhaust manifold and the intake manifold.
Also, the potentiometer used in this system to determine the position of the EGR valve is a key and efficient component of the EGR valve, which was explained in the previous section.

EGR Air Intake Throttle: The air intake throttle, also known as the throttle body, is a valve that calculates the total amount of air entering the engine. It is located between the intercooler and the intake manifold.

EGR Cooler: As we explained in previous sections of this article, the EGR system works by cooling the gases returned to the manifold. Therefore, the system definitely needs a cooler to accomplish this, and that function is performed by the EGR cooler.

The EGR cooler increases the efficiency of the EGR system. The EGR cooler itself consists of an "EGR cooler bypass" and an "EGR cooler bypass valve."

The EGR cooler is located in the EGR channel and can be bypassed during the cold start process.

High Pressure EGR

Generally, there are two types of EGR systems: high-pressure EGR and low-pressure EGR. Of course, there are EGR systems that utilize both high-pressure and low-pressure EGR simultaneously.

High-pressure EGR is designed to be located in the exhaust manifold and upstream of the DPF, DOC, and AdBlue system.

High-Pressure EGR takes exhaust gases from the exhaust manifold and, after cooling them according to the process described in previous sections, recirculates them to the intake manifold, after the intercooler and intake throttle.

The reason for this naming (High-Pressure) is that the exhaust gases from the cylinder, after the exhaust valves open, enter the EGR valve with high pressure due to the significant pressure difference in the exhaust manifold and the engine cylinders.

You can see the diagram of the High-Pressure EGR in the figure below.

Low Pressure EGR

As you can see in the figure below, Low-Pressure EGR is a type of EGR system in which the entire EGR mechanism is located after the DPF and DOC. Then, the particles exiting the DPF enter the EGR and from there are sent through a pipe to the intake manifold, before the turbocharger.

With the explanations provided for High-Pressure EGR, you can probably guess why this system is named "Low Pressure EGR": it's due to the lower pressure of the gases entering the EGR valve. This is because in Low-Pressure EGR, these gases enter the EGR after exiting the DPF, which significantly reduces their pressure. This is why these types of EGRs are named Low-Pressure EGR.

In terms of emission reduction, the low-pressure EGR system is more beneficial and efficient than the high-pressure EGR system and has significantly less soot because a large volume of soot and pollutant particles are absorbed by the DPF system after the gases exit the DPF.

There is another type of EGR system that utilizes both low-pressure EGR and high-pressure EGR simultaneously. This system is known as a hybrid EGR system or a dual-loop EGR system, and you can see how it works and its general layout in the vehicle in the figure below.

Where is the EGR located?

As explained in the previous two sections, depending on whether your vehicle's EGR system is high-pressure or low-pressure, you can find the EGR in the following locations:

In high-pressure EGR systems: In these systems, the EGR valve and its other parts are located after the exhaust manifold and before the DOC and DPF systems.
In low-pressure EGR systems: In low-pressure EGR systems, you can find the EGR valve and its associated parts after the DPF and DOC and before the exhaust throttle.

Why is EGR delete performed?

Regarding EGR, the issue isn't just about reducing emissions. There are many reasons that provide justification for an EGR delete.

One of the most significant problems that arises for the EGR system is damage and malfunction of the EGR valve. This usually manifests as corrosion in the EGR valve, which is caused by the presence of gaseous sulfur oxides in the exhaust gases. During a chemical reaction, these oxides create sulfuric acid, resulting in corrosion of EGR components and incurring very high repair costs.

Additionally, it's important to note that the EGR system itself leads to increased fuel consumption in diesel vehicles, which in turn increases wear and tear and costs for your vehicle in the short and long term.

Another reason for removing the EGR is to achieve better performance. With the EGR in place, combustion efficiency is lower, and heat dissipation is greater. This leads to the entry of unburnt fuel and more carbon, which significantly impacts engine durability. This is one of the disadvantages of the EGR system. This very factor prompts vehicle owners to perform an EGR delete in order to achieve better performance.

It can almost be said that EGR off is essential for a suitable Stage 2 remap aimed at increasing horsepower and torque. It is obvious that in Stage 3 remaps, EGR off must be done so that the car can see higher numbers on the dyno and performance tuning/stage tuning can be done in the best way.

EGR failure