On Sunday, October 4, 2015 at 10:33:33 PM UTC-4, sms wrote:
On 10/4/2015 2:39 PM, Klaatu wrote:
"Ewald Böhm" wrote in message
...
Apparently Volkswagen/Audi cheated on the USA emissions tests since
2009 to 2015 by turning off the EGR to lower nitrogen oxide emissions
ONLY when the car was being tested for emissions.

REFERENCES:
http://blog.ucsusa.org/volkswagen-ca...cle-recall-887
http://www.engineering.com/AdvancedM...EPA-Tests.aspx

http://hothardware.com/news/vw-inten...-482k-vehicles

etc.

My question is HOW did the car *know* it was being *tested* for
emissions?


According to NBC, the emission controls were altered when only the front
wheels were turning, as on a dynometer.

I don't know about diesels, but newer gasoline powered cars in
California don't use the dyno anymore. The levels are all read from the
sensors via the OBD-II port, at least in California.

I'm not sure they even read levels. They do check to make sure the
emission ready monitors have been set, which indicates that if the
computer has been cleared, then the car has been driven long enough
to reset them. Other than that, they are probably relying on the
computer not having any emissions failure codes set. The cars don't
have the instrumentation to measure all or maybe even any of the
actual emission components directly. Whatever they measure, it's
obviously even easier to cheat when only the OBD is used. The computer
just says everything is OK all the time.