VW Emissions: The Science

Unclear on the technical issues behind the VW emissions scandal?

A number of terms have been used to describe the core problem behind the VW emissions scandal. You’ve probably heard the terms ‘defeat device’ or ‘cheating software’. Both are actually describing a component that’s in all modern cars; the Engine Control Unit (ECU). The ECU is essentially a computer that controls the performance of the engine.

What’s unusual about the ECU in the affected diesel engines in VW, Audi, Skoda and Seat cars, is that it has been deliberately manipulated to ‘cheat’ or ‘defeat’ emissions testing.

What’s an Engine Control Unit (ECU)?

The ECU Sensors:

The ECU controls how the engine responds to various inputs from sensors in the car and from driver behaviour. These inputs can include:

  • the throttle position
  • incoming air temperature
  • engine coolant temperature
  • oxygen concentration in the exhaust
  • steering activity
  • volume of air flow into the engine, and
  • the timing or positions of a number of mechanical parts of the engine.

How the ECU responds:

Almost in an instant, software programed in the ECU then determines how the car responds to the information coming from the various sensors. Among other things the ECU can adjust include:

  • the ratio of air to fuel via the fuel injectors
  • the ignition timing – the timing of the spark that ignites the fuel
  • the control of the idle speed – especially when the engine is cold
  • the timing of when air intake valves open

These adjustments change the performance of the car and importantly can have a big impact on the car’s emissions.

My car’s affected by the VW Emissions Scandal – what’s wrong with the ECU?

In the Volkswagen, Audi, Skoda and Seat diesel engines affected by the VW emissions scandal the ECU has been programed to detect when it is undergoing emissions testing.

The emissions tests are highly standardised and are used to certify that a car complies with emissions standards. These tests are conducted in a high tech laboratory under controlled conditions that are readily replicated.

The car is positioned on computer controlled rollers, which can change the resistance and help simulate different driving conditions. Even the composition of air entering the car is strictly controlled. The exhaust gases are fed into analytical computers that see how the exhaust emissions change in response to different driving conditions simulated by the rollers and the throttle.

The ‘cheating software’ knows that the car is being tested, by detecting things like the absence of inputs form the steering wheel. It then changes engine performance to improve the emissions outputs. Then, when the car is on the road under normal driving conditions, the cheating program is not initiated and the emissions are much higher than measured under testing conditions.

Volkswagen cheated the system. So what?

Many owners of cars affected by the defeat device has asked the team at Bannister Law the simple question – what’s the big deal? The car’s performance is mostly unaffected; it’s not impacting the engine’s power, its life or fuel efficiency. The emissions may be higher but why does that matter?

Aside from impacting your trade in or resale value, the emissions scandal is creating a pollution problem.

The main gases that the cheating software is influencing are nitrogen oxides (NOx). These are a group of gases made up of nitrogen and oxygen which have both health and environmental impacts. There are good reasons that globally, governments and car makers have been working together to lower levels of NOx.

Impacts of Nitrogen Oxides (NOx)

Health impacts:

Studies have shown that long-term exposure to the NOx levels currently observed in Europe may increase the risk of respiratory symptoms such as acute bronchitis may and decrease lung function especially among children. Also people with asthma and children in general are considered to be more vulnerable.

Some studies have gone as far as to estimate the number of people who may die as a result of the Volkswagen emissions scandal.

Environmental impacts:

NOx react in the presence of heat and sunlight to form smog (ground level ozone) and acid rain. While less of a concern in Australia, acid rain damages; causes deterioration of cars, buildings and historical monuments; and causes lakes and streams to become acidic and unsuitable for many fish.

Breach of Consumer Law

The mere presence of cheating software is a breach of Australia’s emissions standards. Additionally, the emissions levels without the defeat device are likely to be in breach of Australia’s standards around NOx. Bannister Law contests, that these vehicles do not comply with Australian standards and should never have been sold in Australia.

While the reason people chose a particular make and model of car is varied, for some people the environmental standards are important. VW understand this and often vehicles affected by the cheating software were marketed as ‘clean diesel’.

For other people emissions may not feature in their considerations when buying a car, yet they have an underlying assumption that their purchase meets Australian standards and is neither harmful to public health or the environment.

We contest that the sale of vehicles with the defeat device is deceitful and misleading and a breach of Australian Consumer Law.

The Fix

VW has already suggested that it has a technical fix to the problem including the reprograming of the ECU and the inclusion of device (a flow transformer) which changes air flow in the engine and improves the accuracy of one of the engines sensors.

While VW claim that this fix will not impact the performance of the vehicle, its engine life or fuel economy, there remains considerable scepticism around these claims. Considering the magnitude of the deceit, it does beg the question – if the fix is that easy, why was it not deployed years earlier?

Ultimately, time will tell as to whether the VW fix adversely impacts the affected cars. Although some owners may be indifferent to emissions levels, many are very concerned if any fix changes the performance, engine life or fuel efficiency.

Whether the fix does what Volkswagen claims or not, the VW Group and the brands VW, Audi, Skoda and Seat have all suffered massive brand damage which may not be recoverable.

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