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UPDATE: VW Denies Alegations as VW, Audi, Porsche Slammed as EPA Finds Additional Violations under Clean Air Act

We might have just passed Halloween, but the nightmare that is Volkswagen’s wanton disregard for emissions targets and purposeful cheating on the same has taken a new twist.

Volkswagen is in trouble again for emissions cheating -- this time with its V6 TDI models.

Volkswagen is in trouble again for emissions cheating — this time with its V6 TDI models.

Despite Volkswagen’s protestations, the German automaker — and its luxury Audi and Porsche brands — has been caught cheating on emissions the second time this year. And this time, it revolves around 2014 through 2016 Volkswagen, Audi and Porsche SUVs and sedans fitted with Volkswagen’s latest-generation 3.0-litre diesel engine.

This includes V6-Diesel variants of the  2014 Volkswagen Touareg, 2015 Porsche Cayenne, and 2016 models of the Audi A6 Quattro, A7 Quattro, A8, A8L and Q5.

That badge spells a whole lot of trouble right now.

That badge spells a whole lot of trouble right now.

It’s been more than six weeks since the U.S. Environmental Protection Agency first announced it was issuing Volkswagen AG a formal Notice of Violation under Part A of Title II of the Clean Air Act for “purposefully manufacturing and installing defeat devices in certain model year 2009 through 2015 diesel light-duty vehicles equipped with 2.0-litre engines.”

Today, it issued a second formal notice of violation for a similar type of behavior in SUVs manufactured by the automaker and its associated brands. Like the first violation, the EPA has detected a noticeable difference between emissions when in ‘testing’ mode and when in normal drive mode.

For those unfamiliar with the cheat device, it is essentially a software algorithm which allows Volkswagen vehicles to detect when they are being driven on a dynamometer — the type of rolling road used in all official fuel economy and emission test routines.

When the car’s engine control unit detects it is being driven in a laboratory on a test bed, code within the unit ensures that fuel mix and engine parameters are tweaked to ensure emissions targets are met. When on the open road, the unit ignores emission targets altogether, tweaking the engine timing and fuel mix for fuel economy and power at the detriment of tailpipe emissions.

In the case of the original 2.0-litre engines tested by the EPA in the original scandal, Volkswagen’s engines were found to emit up to 40 times the U.S. EPA targets for NOx when driven in ‘normal’ mode. According to today’s citation from the EPA, the affected SUVs emit up to 9 times the safe NOx limit.

The 3.0-litre TDI 2015 Porsche Cayenne is also involved in the alleged cheating.

The 3.0-litre TDI 2015 Porsche Cayenne is also involved in the alleged cheating.

One of the reasons given by industry insiders for the original cheating was one of cost-cutting. Rather than use an expensive Selective Catalytic Reduction System to capture excess NOx in the exhaust gasses or an even more expensive AdBlue Urea injection system to convert the toxic NOx into harmless water (H2O) and nitrogen (N2), someone at the Volkswagen decided to circumvent the regulations altogether by building the cheat switch.

In the case of the vehicles now cited as being non-compliant, Volkswagen appears to have used Selective Catalytic Reduction and AdBlue yet still found the need to cheat on emissions.

The Audi A7 TDI Quattro is also involved.

The Audi A7 TDI Quattro is also involved.

Operationally, the software — while it likely uses a slightly different code base to offer the same end result — behaves in exactly the same way: it detects if the car is on a dynamometer, and adjusts its emissions accordingly.

Implementation is slightly different. Since the V6 3.0-litre TDI engine is designed to work with a Selective Catalytic reduction system, Volkswagen’s ECM code forces the engine into a so-called low NOx temperature conditioning mode when it detects that the car is on a dynamometer.

In this mode, it uses a variety of tricks, including injection timing modification and changing of the fuel pressure to ensure that low NOx emissions are achieved. It also increases the exhaust gas recirculation rate — a system which feeds hot exhaust gasses back into the inlet in order to help the engine warm up more quickly and at the same time, improve the efficiency of the selective catalytic reduction system.

As a consequence, NOx emissions stay low.

It's not clear at the moment what will happen next.

It’s not clear at the moment what will happen next.

Just one second after the completion of the initial 1,370-second FTP 75 Federal emissions test procedure — at which point the test would ordinarily be completed — the engine management system switches to a ‘normal’ drive mode in which exhaust gas recirculation rate, injection timing and fuel pressure are tweaked for performance and economy rather than emissions.

At this point, NOx levels rise considerably.

Moreover, the NOx temperature conditioning mode is skipped entirely as soon as the vehicle determines it is not being driven on a test bed, emitting up to 9 times the acceptable NOx limits outlined in the Clean Air Act.

While Volkswagen has yet to offer an official statement at the time of writing, the news is likely to severely rock the automaker, which has already faced criminal investigations on multiple continents for its conduct thus far. Fines, say the EPA, will be levied in due course, along with the passing of the matter to the U.S. Department of Justice for ‘initiation of appropriate enforcement action.”

As with the previous violation, expect sales of affected vehicles to cease immediately and no new 2016 model-year cars from the Volkswagen group to be approved for sale by the EPA until the matter has been successfully resolved.


UPDATE, 3:35pm EST: Volkswagen North America has just released the following official statement, flatly denying all new allegations.

The United States Environmental Protection Agency (EPA) informed Volkswagen Aktiengesellschaft on Monday that vehicles with V6 TDI engines had a software function which had not been adequately described in the application process. Volkswagen AG wishes to emphasize that no software has been installed in the 3-liter V6 diesel power units to alter emissions characteristics in a forbidden manner.

Volkswagen will cooperate fully with the EPA clarify this matter in its entirety.


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  • Michael Thwaite

    So, they got caught breaking the rules on the 2 litre and didn’t think to raise their hand to confess to the 3.0? Seriously, what else are they cheating us on?

    • vdiv

      Hmm, the rear windows opening AND closing? 🙂

  • MEroller

    Quote: “Rather than use an expensive Selective Catalytic Reduction System to capture excess NOx in the exhaust gasses or an even more expensive AdBlue Urea injection system”

    Selective Catalytic Reduction as such REQUIRES the Urea injection system, there is no SCR without the Urea injection.

    The slightly cheaper alternative NOT requiring the Urea injection is to use a NOx adsorption catalyst: it captures NOx for a few minutes until it’s storage capacity is reached, then the engine needs to start a regeneration cycle with higher exhaust temp. and richer combustion which allows the adsobtion catalyst to transform the stored NOx to less harmful N2 and CO2 and releasle it to ambient, thus freeing up new NOx storage space. This is the technology VW chose for the lighter Jetta, thus saving the buyer around 300 initial $, but requiring “special calibration” to pass the EPA testing cycle and otherwise causing higher fuel consupmtion.

    The up to 9-fold higher real-world NOx emissions of V6 3-liter TDI engines now put on VW’s table by the EPA seems quite normal to me, as all cars have far higher fuel usage and thus also emissions in real driving compared to the toned-down dynamometer emission test cycles still in use. I would wait a bit before jumping to conclusions…

  • vdiv

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