So you save yourself a bit of money but are happily breaking the law. Hopefully they will introduce mobile testing equipment and crush any cars they find which have disabled exhaust conditioning devices. I am surprised you have not drilled out the DPF while you were at it.

There is a trade off between NOX and soot emissions in a diesel.

EGR reduces combustion temperatures and hence NOX formation as this pollutant is largely temperature dependent. However lower combustion temperatures mean more soot in the exhaust which can in theory be handled by the DPF. ..

Whether this is better for the environment is debatable. DPF's don't remove superfine PM10 particles that get into your bloodstream..so having the egr deleted *might* better control this lethal pollutant as the fine soot is more effectively burnt up...

The EGR valve takes slightly cooled combustion gas, which is consequently richer in CO2 and less rich in Oxygen and feeds it into the inlet gasses for the next combustion cycle.

With less Oxygen there is less energy in the system CxHx +O2 = CO2 +H20

the nett effect is that there is less heat, lower temperature. At lower temperatures less NOx are formed. This is better for air quality, as these NOx are harmful to passing pedestrians, and other road users including drivers.

If you block or remove the EGR there is no recirculation of exhaust gas so you get the full 20% Oxygen. Soot is just unburnt carbon. With more Oxygen in the cylinder there is a better chance of more complete combustion.

It's a trade off soot Vs NOx. I am sure BMW and regulators thought about these things and guy the compromise right. I think your actions are pretty selfish, but hey if your car works better like that forget about the little children eh.

Hi All,

I recently had the EGR function disabled on my F31 330d purely from a reliability point of view and not for performance having seen the horror videos showing inlets and heads clogged up with black gunk. I plan on keeping the vehicle for many years and so i want it to be as reliable as possible and given its a BMW any jobs are not necessarily going to be cheap.

Have you informed your insurer of the modification? An eagle-eyed loss adjuster might spot it.