EGR Valves Tech Tip

tegral to the vehicle’s engine management system, the exhaust gas recirculation (EGR) valve recirculates a metered quantity of exhaust gas to the engine intake system, helping to increase engine efficiency, lower fuel consumption, and reduced NOx in diesel and petrol engines.

The symptoms associated with an EGR valve failure are similar to those of many other engine management issues, and for this reason EGR faults continue to cause problems for many garage technicians.

While knowing how to correctly diagnose an EGR valve is critical for today’s technician, it is equally important that when a failure is found, the EGR is replaced with only high quality parts, in order to ensure the same levels of performance as specified by the vehicle manufacturer. As an OE supplier and partner to 25 of the largest vehicle manufacturers worldwide, Delphi has the unique advantage of collaborating at the OE level, ensuring its aftermarket and OE products meet the same exacting standards. Unfortunately, this is not always true with other aftermarket manufacturers – the possible result, inferior parts that can have a detrimental effect on both the engine’s and the vehicle’s performance. Parts distributors and technicians need to be aware that not all engine management system parts are created equally. But how do you tell the difference? Below are some examples of what separates Delphi’s OE EGR valve technology from the rest.

The first obvious difference when comparing a disassembled Delphi EGR against a competitor product is the variation in pintle quality and valve head shape. The competitor’s pintle is not only different in design from its Delphi counterpart, but there is obvious dirt and corrosion on the lower quality part. This is a sure sign that lower-grade materials have been used to manufacture these parts, which affects EGR valve performance. The difference in valve head shape will affect the valve leakage and the EGR valve flow metering, leading to increased fuel consumption, higher engine contamination and decreased vehicle performance.

The first image shows a Delphi EGR with RTV silicone sealant versus a competitor product without. One of the most common failures of EGR valves is caused by corrosion, whereby moisture and harmful fluids end up inside the valve, which is likely to cause sensor failure. The possibility of this damage is prevented by the protective RTV silicone seal on genuine Delphi EGR valves.

In comparing the sensor technologies of the cut-away valves, there is no doubt Delphi’s technology is superior. The Delphi EGR has a potentiometer, robustly designed and

validated for the intended applications. The competitor product, on the other hand, has a linear hall sensor with a magnet.

There are several disadvantages associated with the use of a linear hall sensor with a magnet. For example, this solution has a different calibration output in comparison with the genuine Delphi solution. Consequently, the sensing outputs will drift with temperature rises and are likely to generate malfunction codes and incorrect EGR valve flow leads to loss of power, as well as higher engine contamination.

The hall sensor technology will also degrade very quickly due to the operating environment, which has high temperature exhaust gases easing the risk of displacement.

Insulation is essential to protect the coil inside an EGR valve. This image of a competitor’s part demonstrates the insufficient amount of insulation used on the copied product, which is no thicker than a standard piece of sellotape!

Without proper encapsulation, or protective insulation around the wiring, the product has an increased potential to fail due to short-circuiting.

Another important difference between a Delphi OE EGR valve and some lower-quality competitor products is the surface finish. There is a great deal of swarf (loose metal

shards/debri) apparent on the competitor product (shown), further demonstrating the inferior manufacturing processes used to produce the EGR valve. Consequences of swarf include engine wear damage on critical components, such as piston rings, valves and cylinder liners, which could lead to reduced engine life.

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Published on: November 1, 2017

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