What Is The EGR Valve?

What Is The EGR Valve?

EGR stands for Exhaust Gas Recirculation. It is a system designed to reduce Nitrogen Oxides (NOx) emissions to meet strict environmental regulations.

When the X-Type's engine burns fuel, high combustion chamber temperatures cause nitrogen and oxygen to bond, creating harmful NOx. To combat this, the X-Type uses a vacuum and electrically controlled EGR valve. At light engine loads, such as steady cruising, the valve opens. A portion of the hot exhaust gas is routed through the EGR cooler and fed back into the engine through the intake manifold.

Because this exhaust gas has already been burned, it acts as an inert filler. It slows down the combustion process just enough to drop peak cylinder temperatures, thereby cutting NOx emissions.

The X-Type's "Black Crust" Problem

The X-Type diesel always runs with an excess of air. When you are driving under light load and the EGR valve is fully open, up to half of the air entering the engine can be recycled exhaust gas.

This creates a serious design flaw over the life of the car. The X-Type's exhaust gas is naturally full of dry, powdery soot. At the same time, the engine's crankcase ventilation system feeds oily vapours back into the intake. When the dry, hot soot from the EGR meets the sticky oil vapour inside the intake manifold, the two combine into a thick, hard, tar-like black crust.

Over time, this crust completely chokes the X-Type's airways. As the engine struggles to breathe, you will notice these symptoms:

• Power drops: The engine is literally suffocating.
• Smoking begins: The car starts producing dark grey to black smoke under hard acceleration. As the intake manifold and the EGR cooler get increasingly blocked, it will blow thick black smoke even at modest throttle inputs.

A simple check you can do yourself: To find out whether your EGR cooler and intake manifold are choked, get the engine hot. With the car stationary, give the throttle one or two hard, full-throttle blips and look under the tailpipe. If you see a wet, sooty puddle on the ground, that is the EGR cooler and the intake manifold violently emptying themselves of the sludge-like soot built up inside them.

Blanking The X-Type EGR

To stop this suffocating cycle, many X-Type owners choose to blank the EGR valve. The job puts a steel blanking plate into the plumbing and closes off the path the exhaust gas takes into the intake.

How the job is done:

Separate the EGR pipe from the valve, fit a 1.5 mm (or thicker) steel blanking plate between the valve and the pipe, then put everything back together. That is all there is to it.

The one exception is the 2.2d auto. On that engine the plate goes on the EGR cooler side rather than the valve side. The reason is below.

The intended benefits for the X-Type:

• Stops the carbon loop: The intake only breathes clean air, so no new build-up forms.
• Restores lost performance: The engine breathes better, bringing back throttle response.
• Reduces exhaust smoke: The engine stops choking on its own waste.

The Real Catch: The 2.2d Auto

Forget the scare stories about limp mode, mapping and MOT failures. On the X-Type, blanking the EGR does not light up the Engine Management Light (EML), it does not require a costly ECU remap, and the engine burns cleaner, so it sails through its emissions test.

The only actual catch comes down to which exact model you are working on: the 2.2 litre diesel automatic.

Because of the physical structure of the EGR valve on the 2.2d auto engines, you cannot slot the blanking plate in on the valve side as you can on the other models. To do it properly on this engine, the plate must be fitted on the EGR cooler side.

The Golden Rule

Even on a straightforward blanking job that needs no remap, you cannot skip the clean-up. Blanking only stops future soot from entering the intake. To actually restore the car's performance, your first job is still to remove and thoroughly clean the EGR valve, the EGR cooler and the intake manifold to clear out the crust that is already in there.