EGR Valve = Exhaust Gas Recirculation Valve.
The EGR valve controls formation of noxious emissions.
Rough idle and poor acceleration can be caused by a faulty EGR valve.
Guide Review – EGR Valve
The EGR valve, or Exhaust Gas Recirculation valve, is a vacuum controlled valve which allows a specific amount of your exhaust back into the intake manifold.
This exhaust mixes with the intake air and actually cools the combustion process. Cooler is always better inside your engine. The exhaust your EGR valve recirculates also prevents the formation of Nitrogen related gases. These are referred to as NOX emissions, and are a common cause for failing emissions testing. Unfortunately, your EGR valve can get stuck, causing NOX gases to build up. You’ll know if your EGR valve is stuck or malfunctioning because your car will experience symptoms like rough idle and bucking on acceleration. Fuel mileage will also suffer, and you may see a Check Engine light followed by a readable code in your car’s OBD-II or newer computer.