Wait, let's get this fukun straight. The EGR valve LOWERs N2O emissions by lowering peak combustion temperature.

It takes a high temperature to burn nitrogen and that is the deal, it combines with the O2 and becomes NO2. This does not happen as much at lower temperatures.

The EGR system allows the intake system to brerathe really well, usually with VEs (volumetric efficiency) over 100 even in normally aspirated engines because of good camshaft design.

you can get all this, and use EGR to make regular gas burn like premium. That is one of the things it does. Lowering the peak combustion temperature, by the laws of physics, will slow down the combustion rate.

Ignition ping is caused by too fast combustion.

Modern cars have a knock sensor and continually advance the base ignition timing incrementally until the knock sensor "reports". Then it backs off. This allows it to give you better performance with better gas. I know this is a diesel, but when it comes to EGR it still does the same thing.

Bottom line, they turned off the EGR until such time the car was under test, ;detected either by the connection of the tester, or the fact that the non-drive wheels were not turning. That information is readily available from the ABS system, and traction control if so equipped.

I am surprised the admitted it. I would have said there is no explanation and we would just pay a fine, like $5 million or so to your favorite charity as well.

"Golf on Wednesday ?"
"Definitely, we are going to kick your ass"
"Really"