Exhaust Gas Recirculation systems, or EGR

EGR is short for Exhaust Gas Recirculation. EGR systems are a common fitment on many modern vehicles worldwide, both petrol and diesel, and have been used by manufacturers now for many years.

The EGR system is designed to reduce the amount of nitrous oxide present in vehicle exhaust emissions. In basic terms, it works by taking a small proportion of the exhaust gas and introducing it back into the engine prior to the next combustion cycle. Nitrous oxides are produced partly as the result of high combustion temperatures and the reintroduction of some exhaust gas reduces cylinder and fuel burn temperatures. Exhaust gas recirculation is, for vehicle manufacturers, a relatively simple way to ensure engines meet various worldwide specifications for exhaust emissions. Originally relatively crude and simple, EGR has become far more widely used as electronic control systems have developed. These allow more precise control of the amount of gas recirculated, which can be changed depending on temperature, engine speed and other factors.

There are a number of weaknesses and problems associated with EGR systems, the most important of which concern reliability and overall efficiency. The system is inherently part of the exhaust of a vehicle, and for various reasons it needs to be located at the closest possible point to the engine block. The actual operation of the unit involves at least one variable valve as part of the system, which requires electro-mechanical control. Naturally, the physical location means the entire mechanism is subjected to extreme variations in temperature and significant vibration, and over the long term, this can result in mechanical failure. Problems are also not uncommon with the electrical activation of the valve or valves. In addition, over extended mileages, parts of the system can become blocked with carbon deposits that cause eventual failure. This latter issue is particularly the case for diesel vehicles. With regard to efficiency, an EGR system does increase fuel consumption and reduce performance to some extent, although this is minimal with later vehicles and more modern systems. In the vast majority of cases, exhaust emission compliance could be better met by ensuring maximum efficiency through more precise engine management programming. However, in view of the fact that a model of vehicle may be sold and used within a substantial number of different countries, and where fuel quality and general conditions may differ accordingly, vehicle manufacturers are reluctant to do this, as it would increase production costs and reduce production flexibility. For a manufacturer, the fitment of an EGR system is a relatively low cost way to meet standards.

In many, if not most, cases where a problem occurs, EGR removal may turn out to be the most cost-effective and sensible option. However, it must be stressed that simply removing the components themselves or 'blocking' part of the software control is not enough. Unless the procedure is carried out correctly, economy may be harmed and even severe engine damage is possible. Correct EGR removal entails a complete reprogramming of the vehicle's engine management computer, and the results in the vast majority of cases are improved running, improved performance and reduced fuel consumption. As long as it is carried out properly, EGR removal will have very little effect on a vehicle's exhaust emissions, particularly for an older vehicle, and MOT standards will easily be met. Vehicles will remain suitable for use in the vast majority of countries (and certainly all of Europe), where fuel standards are now harmonised.

At MK T and B Centre, we have the correct equipment and programming information to be able to correctly perform EGR removal for the vast majority of vehicles. Our technicians are trained and experienced in the correct procedures to effectively, efficiently and safely remove EGR systems with no harmful effects. Please contact us with your requirements. If you get a dashboard warning of EGR problems, it is vital to have the issue resolved quickly, or serious (and costly) damage could result.

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