I recommend you the book ” Faster, Higher, Farther: The Volkswagen Scandal” by Jack Ewing. Here is a brief summary of the problem exposed extensively in the book. But from a specific perspective: that one of the technology, both of the combustion engine and of the emissions
Rudolf Diesel invented diesel technology at the end of the 19th century. Diesel is a petroleum distillate obtained by a process different from that of gasoline. In a diesel engine the fuel is compressed in the cylinders along with the oxygen and the combustion is produced by ignition derived from the pressure. In a gasoline engine it is not the pressure of the pistons that produces the ignition but it is the spark of the spark plugs. The diesel fuel savings are due to the fact that the more dense and compressed fuel and oxygen mixture combust more intensely than in the gasoline engine. However, diesel engines have traditionally been heavier than gasoline engines because the more stressed mechanical pieces (the combustion process produces more torque) must be more robust. In addition, the diesel engine had been noisy and with vibrations. The engines based on this technology were used for many years in trucks and boats. Diesel, in this transport, meant a significant saving, both for lower fuel costs and also for longer engine life.
The major automakers, in the context of the oil crisis of the 1970s, set out to move that diesel technology to automobiles. For example, Mercedes-Benz was selling a turbo sedan in the late 1970s. But it was Volkswagen and Audi who tried to adapt the technology to middle class cars. Thus in 1976 Volkswagen had launched a diesel version of the Golf. At the end of the 80 Audi launched its TDI, turbo charged direct injection or turbo direct injection. They were based on electronics and computer technology to better control the turbocharger and fuel injector with the aim of providing the proper mixture of air and fuel to the engine according to its demand. The resulting diesel still vibrated but much less and no longer emitted the huge black clouds through the exhaust pipe. Ferdinand Piëch universalized Volkswagen’s commitment to diesel and also extended it to the American market.
But diesel has serious drawbacks in terms of emissions. Although it generates less carbon dioxide, responsible for the greenhouse effect, it emits particles of soot and oxides of nitrogen, very harmful to human health (asthma, bronchitis, cancer …). It is the component that forms smog in large cities. Already in the 70s the authorities controlled the emissions. For example, the 1970 United States Clean Air Act obliged car manufacturers to reduce 90% emissions of carbon monoxide and hydrocarbons and also nitrogen oxides before 1976. Europe did not have a unified EU quality standard air emissions law until 1980. Reducing emissions at that time was achieved with improvements in the injection technology, spraying the fuel in the cylinders instead of mixing it with the air in the carburetor. US authorities were trying to ensure that the diesel cars that spilled across the country in the 1980s and 1990s was clean. To measure emissions, they tested the cars in a laboratory on rollers. It was therefore a measure of the emission under controlled conditions. Little was known about the real emissions on the road. It was an exam for which automakers already knew the answers. This awareness of the known exam motivated a growing willingness to measure the real emission conditions on the road.
Volkswagen and the rest of the manufacturers tried to get the level of emissions requested by the US authorities and measured in the laboratory. As for nitrogen oxides, diesel car manufacturers had developed several emission reduction technologies:
- Urea based SCR systems (BlueTech) – Selective catalytic reduction (SCR). Volkswagen had obtained Bluetech technology from Daimler, maker of Mercedes-Benz. That technology used a solution containing chemical urea to decompose the nitrogen oxides in the exhaust pipe into an innocuous form of nitrogen and oxygen. The technology was effective but had drawbacks. For example, the price of the car increased by about 330 euros. In addition, a deposit of urea was required which had to be refilled periodically. And for that periodic filling to coincide with the annual survey of 15,000 km, the urea deposit must be too large. Volkswagen could not afford anything that would make its diesel cars lose appeal. On the other hand, the technology was not its own. The Volkswagen engineers had their pride and did not believe in a Daimler technology (the “not invented” syndrome).
- LNT Lean Nox Trap or NOx adsorber. It was a kind of catalyst that trapped the nitrogen oxides in a chamber and separated the molecules into oxygen and diatomic nitrogen, a harmless form of nitrogen found in abundance in nature. NOx trap technology was cheaper than Daimler’s urea solution and did not require maintenance by users. But it had a serious drawback: it was not able to completely neutralize emissions of nitrogen oxides.
- EGR Exhaust Gas Recirculation. It is a technology that relies on the system to recycle some of the exhaust gases and sends them back to the cylinders. Exhaust gases, with less oxygen than air in the atmosphere, reduce the combustion temperature and this reduces the production of nitrogen oxides. But this causes the engine to produce more fine carcinogenic particles. These soot particles also affects another component of the system: the filter that traps them. The American emission regulations were very strict and demanded that the emission systems had the same useful life as the car. Therefore, changing the filter was not a legal option. In addition, it would have been inconvenient for the users.
In 2006 Volkswagen realized that it had a problem with its emissions in the United States: It used the NOx Trap technology. But it was not enough and so they also used EGR exhaust gas recirculation technology. However, this required an effort on the particulate filter which was worn out prematurely. Some of the car manufacturers (Mercedes or BMW) used the three technologies mentioned above to comply with the emission regulations. However, obviously that affected the price. Volkswagen placed its cars in a segment of the market in which the price was a decisive variable. On the other hand, the managers of Volkswagen did not like, for their cars, an additional deposit, the chemical urea deposit. They did not know how to solve the problem.
In addition, Volkswagen had been working, for 10 years, for its American diesel cars, with its own motor technology: The Pumpe Düse, or unit injector. This type of diesel motor injected the fuel at very high pressure, twice as much as previous technologies, which increased efficiency. But common rail diesel technology was becoming the industry standard for its even greater efficiency and lower emissions. In addition, common rail engines were more economical (among other reasons, for being widely adopted). Finally, Volkswagen chose the diesel technology of the common duct, which required an adaptation effort.
As Audi had already used common rail for a while, in 2006 Volkswagen engineers, to speed up and avoid starting from zero, adapted the Audi software containing thousands of control functions to their engines. In that adaptation they found the solution to the problem of their emissions. They found the “noise function” or “acoustic function” that made it possible to recognize when the car was in a laboratory test on rollers. The software was a manipulation device. The emissions reduction unit was activated when the car recognized that they were analyzing it. The rest of the time, the emission reduction system stopped working to protect the particulate filter. The software was in the so-called engine control unit (ECU). Bosch developed these units on behalf of Volkswagen and in close collaboration.
Already in the current decade, Volskwagen developed its own SCR technology based on urea called BlueMotion that applied to its new diesel engines from 2012. This new technology based on urea continued to have malicious software: At the time of the car-test in the laboratory, more urea was sprayed into the pollution control system so that the emissions of nitrogen oxides were within the legal limits. If no evidence of car control was found by the software (so, in normal circulation), the software rationed the urea so that it lasted at least 16,000 km (and the tank could be refilled at the annual review).
It is well known that the US Environmental Protection Agency eventually discovered that these diesel engines emitted up to 35 times above the limits allowed when they were traveling by road. In September 2015, the world learned Volkswagen had installed that illegal software in 11 million cars. A team of researchers led by Dan Carder at West Virginia University discovered the fraud while testing the diesel cars, sold worldwide between 2008 and 2015, out on the road. According to Jack Ewing, the use of these fraudulent devices for so many years and at the same time that Volkswagen shouted to the four winds its commitment to the environment seems an extreme case of corporate cognitive dissonance.