VW America ordered to recall 500,000 cars

Just read this on the Tesla forum about VW circumnavigating US emissions law

 

A Tesla forum? Discussing how green the world is and how your saving the planet?

Am over in the states at the moment and there are a lot of them here so can't all be bad !

 

If you look at the forums membership , they're a lot more popular than our VW'S

I'm not getting one because it's green I'm getting one because the taxman isn't fleecing me for having this luxury performance car that seats 7 people if we feel the need

 

So in a nutshell, VW have admitted installing code detect when they're doing emissions testing and switch to a special mode just to get through it. Real emissions may be 40x higher.

They have been found out and could face massive fines.

oops

 

The US has had extremely tough emissions control laws for diesels ever since 2008. Meeting the NOx target in an emissions cycle is a relatively achievable thing to do.

However meeting the NOx target during random drive cycles - at random temperatures and altitudes becomes a much larger task and is a large chunk of development time. No manufacturer was asked to be able to prove their real world drive cycle emissions as far back as 2008.

The defeat device law was meant to serve as the point to manufacturers that you must attempt to control NOx emissions as far as is reasonably achievable.

Some of the reasons for such a defeat device I can think of are below:

* As NOx levels are reduced Soot production will go up and fuel consumption is marginally reduced.

* Greater Soot Production Fills Up the DPF faster and will require more regenerations

* More regenerations will significantly Increase fuel consumption - and probably shorten the DPF's lifespan

* Higher Flows of EGR will lead to faster clogging of EGR valves and other such engine problems common with modern "clean diesels"


I do not think VW will be alone in creating more NOx in these non standard drive cycles - however the admission that they are actively "defeating" NOx emissions control is clearly wrong. But VW hold the majority share of the diesel passenger car market in the USA so are clearly the EPA's number 1 target.

The type of testing that the EPA has used to file this Notice was "out of the rule book" when VW produced these cars - but prohibition of the use of a defeat device is within those rules.




Most of this is irrelevant though as it seems like 90% of TDI owners in America hot foot it to a "tuner" who turns off EGR and deletes the DPF as soon as possible.

 

http://www.bbc.co.uk/news/world-us-canada-34298259

Recall could cost VW 11 billion, ouch.

On top on the TFSI oil burning recall the US market isn't good for VAG at the moment.

 

Diesels, NOx, Soot, The challenge, EU and US, test schedules, how compliance enforced

In mid 2006 the sulphur content of US Diesel fuel for use on a public highway reduced by the EPA to 15 ppm, inline with what has been in Europe.
This means diesel technology, such as engine hardware and exhaust after treatment hardware in use on EU engines could be used in the US market and meet their durability limits.
VW/Audi entered that market with several TDI powered vehicles when that fuel was fully phased in around 2009.
This on the back of their campaign of diesel tech seen when promoting TDI technology with their winning Dakar Touareg.

NOx and Soot formation summary.

Looking at the the chemical interaction of the combustion cycle of a diesel engine, one then starts to understand how the NOx and soot is generated and what solutions technology and calibration methods come up with to overcome.

Diesels are by nature a NOx generator. Unlike spark ignition engines, that have some time to homogenize the fuel/air mixture in the intake/compression stroke, diesels use the pressure and heat from compression to auto ignite the fuel injected into excess air, just a few miliseconds before auto ignition. Cylinder pressures and heat are much more significant and last longer than in a petrol engine. This condition is ideal for chemically creating nitrides of oxygen. With pressure and heat from diesel combustion being much more higher and longer than spark engines, high levels of NOx end up in the exhaust feed gas.

The other issue with the diesel combustion is soot formation from the lack of mixture preparation before just a few mill secs of compression ignition.
Areas of that fuel rich in the combustion plume are consumed and go out the exhaust as soot or particulates.

How to Control?

To control NOX emissions and soot, the calibrator has:

• Multiple injections
• Mapped Injection timing and duration
• EGR control
• High fuel injector pressures 1800-2500 bar
• Lean NOX trap, DPFs and also Selective Catalyst Reduction.

It takes several months of development to get those features to be calibrated while still delivering, drivability, fuel economy, and low noise.

OEM Challenges.

With emission laws becoming more stringent worldwide, customers requiring more powerful an quiet engines, with no smoke, technology and calibration methods have to answer the challenge to move Diesel engine as an acceptable power source.
In addition to the above, there is the challenge of fuel economy targets, which relate to fuel flow.
All these attributes need to be delivered and the OE needs to be profitable.

EU NEDC Cycle (Light Duty Vehicles).

On a typical EU5 New European Drive Cycle (NEDC) it is quite a complex effort to achieve the legislative limits for diesel exhaust emission while trading off with the other required attributes

Complex when you consider the NEDC is pretty gentle with gradual transients and steady states cruises.



The above cycle is split into two phases an urban phase with a cold start, idle and drive from 20 deg C with 4 repeated sets of accels and cruises. Then at 800secs or so an extra urban phase to simulate motorway driving up to 120 kph.

The current tailpipe limits for EU5a/b and 6 are given in the table below.



NOx limits get even more stringent from last year and from EU5b there was requirement to limit the number of particulates.

They are deterioration factors applied for green catalysts which would perform considerable better than components that have aged are up to 160k kms. OEMs are certified/homologated on green cats and do development cycles on in use parts to ensure they conform to random spot checks.

That looks easy I hear you say! Really? Then consider the next section.

US Federal test Cycles (LDV and LD Trucks)

The main test cycle for to determining emission compliance is the FTP75.

This test is highly transient, to simulate a typical American cold start and drive followed be a transient phase.There is a pause for 10 minutes which is followed by a hot start with the same drive as in the the cold phase.

Cycle scheduled speed trace is show below.



Non green states adopt the Tier 2 standard and green states as California adopt the CARB LEV2 standard.

The limits for those standards are shown below.

Tier 2



LEV2


In addition several supplementary cycles are run and the data captured and they are:
SFTP US06 - simulating aggressive highway driving
SFTP SC03 - simulating emissions associated with the use of air conditioning units.

These are all highly transient cycles and certainly not random.

There are routine spot checks on an OEM product fleet, within the useful life of the after treatment system and you will need to conform to the limits as certified. These checks can occur at Government approved centers.

I should note, certification is often at the OEM's approved test center and you are expected to send all documentation to prove compliance.

What does this relate to the headline?

Volkswagen TDI products destined for the US, would have been certified back in 2009 as either LEV2 or Tier 2. It would appear a spot check has revealed an over legal result for NOX at an independent test facility.
It would appear from this headline the applicable Tier 2 70g/mi NOx target cannot be achieved in real life and no doubt CARB would be interested in how this discovery would affect their limits for LEV2! A further deep dive has claimed engineers found the software to have been calibrated to form a defeat device. It is possible this could be triggered when the vehicle is in 'test' mode, such as will be the case on a emission chassis rolls as seen below.



In the EU 50% sales are diesel. In the US it is ~ 10%.
The VW group has been selling 30% of the fleet as TDI. However they have been still struggling in the US and this comes as a huge blow to them, especially around the same time as the Frankfurt Motor show. It does generate speculation as to the timing of this revelation.
It is claimed VW has admitted to using the software that is considered a defeat device and we watch to see how this pans out.

Sorry about the essay but emissions calibration is pretty complex and quiet a challenge for those having to calibrate it.

 

I was waiting for your response Eddie as I know it's right up your street

Complicated but a great right up thanks

 

Toyotec patent insomnia cure lol

 

There is a lot of chitty chatty about this and the whole what are emissions topic. Thought that post would help in explaining some of the complexity.

 

Thanks for the comprehensive reply Eddie.

I would love to get the "re-released" calibration and the current one for a comparison exercise when one is released.

 

You are welcome.

It may not only be software.

 

Eddie, good insight.

Unfortunately for VW, they appear to have intentionally gone about circumventing the regulations

 

There must have been a good reason to switch off the low NOx strategy though which was running in the drive cycle though, VW would not actively do this unless they had to.

 

There was a good reason, they couldn't sell their cars in America without cheating the emmisions tests.

 

Ah, well I'm sure if they tell the regulators they had good reason, it'll be fine... lol

 

I'm sure they could do it without cheating - but the costs of doing so would have been fairly prohibitive...

 

As excuses go, I`m pretty sure "we could pass the regulations of the land, but we`d make less profit" isn`t going to work