EGR
Exhaust Gas Recirculation (EGR) is a strategy widely used to decrease the cylinder pressure and temperature where a controllable proportion of the engine's exhaust back into the intake manifold. A valve is usually used to control the flow of gas and the valve may be closed completely if required. Despite this strategy can be used to decrease NOx emissions in some operating point, is likely to compromise other emissions (Particulate matter, HC and CO) and have a negative impact on the engine performance. The most relevant disadvantages are listed and explained below.
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Disadvantages and Difficulties of EGR
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Since EGR reduces the available oxygen in the cylinder, the production of particulates (fuel which has only partially combusted) is increased when EGR is applied. This has traditionally been a problem with diesel engines, where the trade-off between NOx and particulates is a familiar one to calibrators.
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The EGR valve can not respond instantly to changes in demand and the exhaust gas takes time to flow around the EGR circuit. Part of the exhaust gases are taken upstream of the turbine, therefore a portion of the exhaust gas energy is taken away from spinning the turbine and this means a slow transient response to the accelerator. This makes the calibration of transient EGR behavior particularly complex. Traditionally the EGR valve has been closed during transients and then re-opened once steady state is achieved. However, the spike in NOx / particulate associated with poor EGR control makes transient EGR behavior of interest.
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The recirculated gas is normally introduced into the intake system before the intakes divide in a multi-cylinder engine. Despite this, perfect mixing of the gas is impossible to achieve at all engine speeds / loads and particularly during transient operation. For example poor EGR distribution cylinder-to-cylinder may result in one cylinder receiving too much EGR, causing high particulate emissions. This causes also an unstable combustion is some of the cylinders, resulting in torque oscillations which can make the drive really uncomfortable.
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Although the term EGR usually refers to deliberate, external EGR, there is also a level of internal EGR. This occurs because the residual combustion gas remaining in the cylinder at the end of the exhaust stroke is mixed with the incoming charge. There is therefore a proportion of internal EGR which must be taken into account when planning EGR strategies. The scavenging efficiency will vary with engine load, and in an engine fitted with variable valve timing a further parameter must be considered.
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EGR Tuning will make your engine more responsive, smooth, clean and ultimately less smoky. A slight decrease in fuel consumption is also noticeable.
EGR tuning is available at no extra cost with one of our remapping options (performance, fuel economy or hybrid).
You can also decide to purchase the EGR delete without any performance improvement.​​
