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Maybe it's just something less evil: diesel engines have some filter which needs to be cleaned automatically. Usually it happens on a highway when driving fast.

by yread 11y ago

Maybe it's just something less evil: diesel engines have some filter which needs to be cleaned automatically. Usually it happens on a highway when driving fast. It increases the emissions a lot when the cleaning is going on. Maybe this software device just made sure that this only happens on highway so they would never measure it in a lab?

noipv4 11y ago
Thats the Particulate filter which needs periodic long distance drive for self cleaning. The VW cars in question have higher NOx emissions.
jstanley 11y ago
AFAIK the software doesn't decide when the DPF gets cleaned, it just happens as a natural consequence of driving fast -- "blowing the cobwebs out" so to speak.
tzs 11y ago
Here is what the software did, according to the EPAs letter to VW: Specifically, VW manufactured and installed software in the electronic control module (ECM) of these vehicles that sensed when the vehicle was being tested for compliance with EPA emission standards. For ease of reference, the EPA is called this the "switch". The "switch" senses whether the vehicle is being tested or not based on various inputs including the position of the steering wheel, vehicle speed, the duration of the engine's operation, and barometric pressure. These inputs precisely track the parameters of the federal test procedure used for emission testing for EPA certification purposes. During EPA emission testing, the vehicles' ECM ran software which produced compliant emission results under an ECM calibration that VW referred to as the "dyno calibration" (referring to the equipment used in emissions tested, called a dynamometer). At all other times during normal vehicle operation, the "switch" was activated and the vehicle ECM software ran a separate "road calibration" which reduced the effectiveness of the emission control system (specifically the selective catalytic reduction or the lean NOx trap). As a result, emissions of NOx increased by a factor of 10 to 40 times above the EPA complian levels, depending on the type of drive cycles (e.g., city, highway). http://www3.epa.gov/otaq/cert/documents/vw-nov-caa-09-18-15.pdf http://www3.epa.gov/otaq/cert/documents/vw-nov-caa-09-18-15....

by yread 11y ago

noipv4 11y ago

Thats the Particulate filter which needs periodic long distance drive for self cleaning. The VW cars in question have higher NOx emissions.

jstanley 11y ago

AFAIK the software doesn't decide when the DPF gets cleaned, it just happens as a natural consequence of driving fast -- "blowing the cobwebs out" so to speak.

tzs 11y ago

Here is what the software did, according to the EPAs letter to VW: Specifically, VW manufactured and installed software in the electronic control module (ECM) of these vehicles that sensed when the vehicle was being tested for compliance with EPA emission standards. For ease of reference, the EPA is called this the "switch". The "switch" senses whether the vehicle is being tested or not based on various inputs including the position of the steering wheel, vehicle speed, the duration of the engine's operation, and barometric pressure. These inputs precisely track the parameters of the federal test procedure used for emission testing for EPA certification purposes. During EPA emission testing, the vehicles' ECM ran software which produced compliant emission results under an ECM calibration that VW referred to as the "dyno calibration" (referring to the equipment used in emissions tested, called a dynamometer). At all other times during normal vehicle operation, the "switch" was activated and the vehicle ECM software ran a separate "road calibration" which reduced the effectiveness of the emission control system (specifically the selective catalytic reduction or the lean NOx trap). As a result, emissions of NOx increased by a factor of 10 to 40 times above the EPA complian levels, depending on the type of drive cycles (e.g., city, highway). http://www3.epa.gov/otaq/cert/documents/vw-nov-caa-09-18-15.pdf http://www3.epa.gov/otaq/cert/documents/vw-nov-caa-09-18-15....