EGR Systems

EGR Systems

What Does My Engine’s EGR System Do?

Nitrous oxides (NOx) are gases formed in the combustion chamber when heat forces together nitrogen and oxygen atoms from the air. The Exhaust Gas Recirculation (EGR) system mixes exhaust gases into the air passing through the intake. Diluting the air/fuel mixture lowers combustion temperatures, reducing the formation of NOx.

While this sounds like it would have a big impact on performance, there is still plenty of air left over for combustion. Even an early, inefficient EGR system reduces power by no more than 3%.

The amount of exhaust gases entering the intake is controlled by the EGR valve. These gases are too hot to introduce directly into the intake, so they pass through a cooler on the way to the valve. These coolers pass the exhaust through a chamber full of piping connected to the engine’s cooling system.

Let’s have a look at some of the common signs which point to a failing EGR valve:

• Rough Idle. Any change in RPM at idle should be cause for concern.
• Excessive Smoke. Modern diesel engines produce next to no smoke.
• Increased Fuel Consumption.
• Decreased Engine Performance.
• Check Engine Light.