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THERE IS technical interest in Volkwagen’s scamming of government and customers. According to Bloomberg Business, almost 500,000 VW and Audi diesels, beginning in Model Year 2009, are involved in the recall. Their “clean diesel” powerplants are fitted with software capable of turning emissions controls on or off, depending upon whether the car is being emissions-tested or used in ordinary driving.
Like the guy marveling about a thermos bottle keeping hot things hot and cold things cold, “How does it know?”
The background: Unlike spark-ignited counterparts, diesel engines ignite their fuel through the heat of compression. Diesel combustion temperatures are a bit higher than gasoline’s. And, as a consequence, a diesel has greater emissions of nitrogen oxides, NOX. Diesel combustion also generates particulate matter, nanoparticles of soot that are especially invidious to the human respiratory system.
Diesel design and calibrations balance control of particulates and NOX. Hotter combustion reduces particulates, but causes more NOX. Less heat generates less NOX, but more soot.
Emissions testing is performed on lab dynamometers (think treadmills for cars); this, to make the testing as accurate and reproducible as possible. Specific test procedures are followed, from which emissions certification as well as fuel economy data are derived.
Our Federal government has two basic test cycles, the EPA City test (evolved from a real-world drive around downtown Los Angeles) and the EPA Highway test (based on a trip in the environs of Ann Arbor, Michigan). Governments at state (and some local) levels have other procedures of periodic inspection.
VW got in trouble when researchers noted discrepancies between emissions-tested data and those derived from actual operation. NOX, in particular, was exhibiting as much as a 40-fold increase in the real world.
As I noted in “Turbo Foot” earlier at this website, “… these clearly delineated City and Highway Cycles offer engineers opportunity to optimize for the tests. There’s nothing deceitful in this; it’s sound engineering practice.”
However, to devise means of differentiating between tests and the real world isn’t optimization, it’s evasion.
So, how do I conjecture it was done? Were it only the EPA Cycles, it would be straightforward to program engine-control software that recognizes the first several seconds of each cycle’s operation and acts accordingly. The EPA City begins with a short idle followed by acceleration and some dithering around 20 mph; the EPA Highway has an immediate acceleration to around 35 mph.
State inspections vary, but a diligent and painstaking engineer could identify common electronic signatures that could trigger the NOX control into action. Absent these, engine calibrations could be optimized for performance, not emissions. This wouldn’t be costly to finesse: Once an electronic system is in place, software programming is cheap.
There could be an even more elementary scam: Many inspections begin with electronic querying of a car’s Onboard Diagnostic system. It would be easy to gin up a cross-linking of the car’s emissions controls and its OBD receptacle: Plug in/NOX control on, plug out/NOX control off again.
Back in 2007, Casper’s Electronics, of Mundelein, Illinois, got caught for marketing its O2 Sim. This gizmo tricked the engine into seeing bogus oxygen-sensor data monitoring its operation. Casper’s was fined more than $74,000 by the U.S. Environmental Protection Agency and Department of Justice for selling 44,000 of these devices.
In VW’s case, the U.S. Clean Air Act of 1970 and its revisions have provision for a maximum penalty of $37,500 per car, more than $18 billion with the 482,000 VWs and Audis involved. Hitherto, the largest automaker fine was less than a tenth of this, Toyota’s $1.2 billion, for its floormats potentially interfering with pedal function.
VW’s outright deceit is rather more serious, with implications in selling, buying or registering the affected cars, even after recall. There is also the possibility of VW executives risking criminal charges. ds
© Dennis Simanaitis, SimanaitisSays.com, 2015