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Steve W.[_4_] Steve W.[_4_] is offline
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Default EPA caught VW cheating - how does the car know it's being tested?

Winston_Smith wrote:
On Tue, 22 Sep 2015 14:22:22 -0700, Ashton Crusher wrote:

You would still need to measure actual
emissions to see if the car met the emissions requirements.


I think this makes sense.

The VW cheat code does NOT appear to do anything clever.

In the official EPA pdf letter to VW, they called it a "switch".

Basically, the cheat code determined that the car was not moving but
that it was running as if it was moving, so, under that circumstance
(i.e., under what the EPA called the "dynamometer" settings) VW
engineers simply reduced the fuel to the engine, which lowered the
NOx emissions.

Under all other circumstances, which the EPA called the "road" settings,
VW engineers let the car have as much fuel as it wanted, NOx emissions
be damned.

There was nothing sophisticated at all about it. It's like me stealing
money from my own relatives. It's easy to do because they leave their
wallet out on the kitchen table without checking.

The audacious part isn't how clever it was (it wasn't at all clever).

The audacious part is that we trusted them, just as you trust a house
guest, and they violated that trust, just as it would be as if a house
guest stole money out of your wallet.


Actually the fuel mapping would be the reverse of that. Running rich on
a diesel reduces NOx because the extra fuel cools the burn. Lean it out
and create more heat and you get higher NOx.

This is the reason why 99% of the VW owners bragged about getting better
mpg numbers than the EPA tests as well.

--
Steve W.