How Come Other Automaker’s Diesels Can Meet US Emissions Standards?

How Come Other Automaker’s Diesels Can Meet US Emissions Standards?

Volkswagen’s ongoing emissions scandal has devastated the German automaker. Its stock price has plummeted by about 30 percent and any goodwill it had with consumers has likely evaporated. But the collateral damage from this fiasco has also given diesels a black mark.

However, just because some of VW’s TDI powertrains violate the law does not mean other manufacturers’ diesel offerings spew out noxious clouds of poison gas. In fact, it appears as though every other automaker is compliant with U.S. emissions regulations.

Still, to ensure there are no additional situations like this one that continues to unfold, the Environmental Protection Agency (EPA) is taking steps to more strenuously evaluate vehicles equipped with compression-ignition engines. Specifically, they will look for so-called “defeat devices,” special lines of computer code that alter the way an engine performs while undergoing an emissions test. This is how VW was able to skirt the rules.

Tech to the Rescue

Volkswagen and Audi models affected by this scandal are powered by the company’s 2.0-liter four-cylinder TDI engine. According to VW’s press release for the 2014 Beetle, it features both high- and low-pressure EGR, an exhaust particulate filter and “no fewer than three catalytic converters: for oxidation, oxides of nitrogen (NOx), and hydrogen sulfide.”

TDI Engine

That’s a lot of high-tech componentry, though, unfortunately, it’s still not enough to meet EPA requirements.

In plain terms, Volkswagen engineers bet on a system that features a NOx trap and a diesel particulate filter. The former component absorbs harmful, smog-forming oxides of nitrogen while the latter traps soot, the emissions component that causes nasty plumes of black smoke. If you’ve ever seen some scalawag “rollin’ coal” chances are their vehicle’s particulate filter is either malfunctioning or missing.

Rolling Coal

To clean an engine’s exhaust, the NOx trap absorbs oxides of nitrogen. When it becomes saturated, the poweplant runs a slightly modified cycle that pumps a little extra fuel into the exhaust stream, which burns off the trapped NOx. In theory, this arrangement works with smaller engines in lighter cars, though that turned out to not be the case, at least with the engine-control software Volkswagen is using today.

SCR = Still Compliant (with) Regulations

SCR is an abbreviation for selective catalytic reduction. This is the emissions-control technology used by practically every other automaker selling clean diesels in the U.S. It functions in a different manner than the system VW adopted.

SCR requires a special urea solution, which adds cost, complexity and extra maintenance. However, the advantage to this technology is that it works. For instance, supplier company Bosch’s latest Denoxtronic 5 SCR system can reduce NOx emissions by a claimed 95 percent while improving fuel efficiency by up to 5 percent. It can help automakers meet LEV II, LEV III and Euro6 emissions standards.

Bosch SCR Technology

This technology features an oxidation catalytic converter, a diesel particulate filter and a special SCR catalyst. As required, precise amounts of an aqueous urea solution are injected into the exhaust stream, which reacts with the SCR catalyst, dramatically reducing NOx by chemically converting it into nitrogen and water.

SEE ALSO: What is Diesel Exhaust Fluid?

Other clean diesels sold in the U.S. features SCR systems. These products range from massive tractor trailers to smaller rigs like the Ram 2500 HD pickup truck. Other models including Mercedes-Benz’s GL350 BlueTEC, the Ford Transit commercial van and Chevrolet Cruze compact car all feature selective catalytic reduction emissions-control systems to keep their diesel engines clean.

And it’s worth noting that not every single Volkswagen or Audi TDI model violates pollution laws. Their larger products are not affected because they feature SCR.

Affected Models

Below is a list of diesel-powered Volkswagen vehicles that are not compliant with U.S. emissions regulations. According to an Audi spokesman, fewer than 14,500 of their cars are affected. Their other TDI vehicles are still available right now, including versions of the Q5, Q7, A6, A7 and A8, which all feature a 3.0-liter diesel V6.

2014 Volkswagen Passat

Currently there is a stop sale on all Volkswagen cars equipped with the company’s 2.0-liter TDI no-so-clean diesel engine.

-VW Jetta TDI (Model Years 2009 – 2015)

-VW Jetta SportWagen TDI (Model Years 2009-2014)

-VW Golf TDI (Model Years 2010-2015)

-VW Golf SportWagen TDI (Model Year 2015)

-VW Beetle TDI and VW Beetle Convertible TDI (Model Years 2012 – 2015)

-VW Passat TDI (Model Years 2012-2015)

-Audi A3 TDI (model years 2010 – 2013, 2015)

The ongoing VW diesel-emissions scandal is probably the biggest automotive news story of 2015. It’s just shocking what the company did and their decision to cheat will have long-term consequences for them and the industry as a whole.

Right now, it’s unclear exactly what will happen next, but a formal recall of affected models is scheduled to begin in January. According to Volkswagen, all of these cars will fixed by the end of next year.

Discuss this story on our Volkswagen Forum

  • Corky

    The really sad thing about this is the fact that VW diesels are really good cars. They’re extremely fuel efficient and they must be pretty clean too even when the hack isn’t working because when you’re stuck behind one you rarely smell diesel.

  • John E Wallace

    I own a 2013 passat tdi and love it. VW wil fix this problem. Adding DEF is not a big deal for me. Probably couldn’t sell if I wanted to. Not happy about the financial hit I have taken. Will be interesting to see what mods are done to emissions system. There have been issues with flapper valves and other components. VW should offer a warranty the new parts for 10000 miles. In the mean time I will keep driving my TDI.

  • KB3MMX

    So…. Why are the SCR equipped cars on the list like the Passat?? Did they also reduce the amount of urea to neutralize the NOX and now they need to crank it back up in the software?

  • KB3MMX

    I believe the TDI carried a target on it’s back to begin with because it could beat the MPG of the hybrid weenie crowd….and it did so with the oh-so hated diesel motor.

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  • Jerry Baustian

    It should be noted diesel passenger cars, which are mostly Volkswagens in the United States, produce about 1/10,000th of total NOx emissions. Between 75% and 80% come from animal waste and farm fertilizers (specifically, anhydrous ammonia, which is a more complex molecule than NO or NO2). EPA cannot do anything about NOx which raises agricultural crop yields, so it goes after VW in particular and diesel engines in general.

  • Andrew David Charles

    Your information is incorrect. This is not about VW’s system without SCR not being able to meet standards. It can. This is about not being able to give the power and economy demanded by VW’s internal development goals. VW’s solution with the EA189 was to simply add software code to effectively deactivate the emissions control functions of the ECU on the road, boosting economy and power about 10%. This affects both lean-NOx trap equipped engines and those with SCR. WVU tested both, both failed road tests by large margins. In later tests investigating this, the EPA found even worse emissions on the road, but again, with the emission control functions active during testing both lean NOx and SCR vehicles could meet emission standards.

    Not being able to meet standards on the road (rather than as VW has done, which is to deliberately defeat emissions controls) is a European-test problem. Unlike the CARB and EPA tests, the European NEDC test is rather basic. The allegations in Europe are that in more comprehensive on road use diesels emit far more than they do in the NEDC.That’s not the case here. WVU testing found a competing diesel performed even better on the road than it did under the tough CARB test, unlike the VWs.This is partly what raised red flags. The point of the WVU test program was meant to see if CARB was a better test than NEDC, or if neither test was adequately assessing real world emissions. They got an unexpected result.

    Don’t forget, as many have, that VW was NOT the leader in clean diesel technology. That’s just VW’s marketing hype. Modern CRDI technology came out of FIAT-Magneti Marrelli, and VW stubbornly persisted with their own internal pump-Duse sytem for years. Lean NOx traps were first promoted by Honda and Peugeot. VW originally used Mercedes’ SCR system. VW clearly found they were behind, and had to cheat to offer both clean emissions during testing, and what they felt was the necessary performance on the road (official fuel economy tests are run on the treadmill, with the emissions system active, so those figures won’t change).

    Although VW of America says the new 2015 MY EA288 engines also require a fix, CR found only a slight difference in perfomance in test mode, small enough to be accounted for by driver variability. VW appears to have used a different strategy to “manage” emissions on the EA288, which they’re hoping will meet EPA approval, although they’ve withdrawn their application for certification while they discuss it.

  • Andrew David Charles

    VW’s problem was not in meeting emissions. That’s lazy reporting. The problem was they wanted better performance on the road and deliberately programmed the ECU to recognize it wasn’t on a vehicle test stand and deactivate functions which controlled NOx but hurt performance and economy. A defeat device is not designed to defeat the test, a defeat device defeats the emissions control system in some way. In the past its only been inadvertent, brief excesses (e.g. running the engine with more fuel when the A/C is cranked at idle) not previously covered by the test, but VW’s software device deactivates NOx control functions practically all the time, and in such a way that the SCR system doesn’t work either.

  • Andrew David Charles

    You should also be aware that for the last decade at least,VW of America has been misreporting engine power to begin with, taking European UN ECE data and just changing “PS” to “hp” and “ECE” to “SAE” with out even applying the conversion factor (1 PS = 1.01387 hp) or applying the required SAE correction factor to adjust for the different atmospheric conditions of the tests.

  • Fred

    KB3MMX you are 100% on the money, VW just announced to be number 1 so thee must have deep pockets, EPA knew this problem for a long time. After all GM killed 180 people with there mess, how many did VW kill ? No comparison. This is a witch hunt.

  • J.R.

    Because these VW engines were designed WITH “Cheat Mode” even if VW fixes this problem by uninstalling the ‘defeat device’ there will still be the major problem of DURABILITY of these engines.
    VW’s solution for its customers is a joke and a fraud.

  • Jonny_Vancouver

    VW announced being no.1 due to heavy marketing, branding and gullible people. It’s only a witch hunt if they haven’t done anything wrong and clearly they have. Sure, they’re nice driving cars, that is until you start having electrical and mechanical problems while the car is still under warranty, but what about after the warranty ends …? How many older model VW’s do you still see on the road? Not very many, and the no. 1 issue is cost of repairs and replacement parts. That’s not a very good car imo. For thousands less I’d buy an import that will last 5 times as long.

  • Jonny_Vancouver

    Good article. Informative. I definitely appreciate more light being shed on this issue. Thanks.

  • chadbag

    I’ve been driving VW since 1989 and have kept most of them for much longer than the warranty period and have not had huge issues with repair costs and replacement costs. The only one that turned into somewhat of a money pit was a used 88 Jetta I bought not knowing it had been in 2 accidents already (back before carfax etc. were available) and after 12 years or so the costs started to mount for it, much of which could be traced to the prior accidents. My 97 Jetta GT we had for 12+ years and was fine when we sold it, with minimal maintenance of wear items. My 06 Passat was doing quite well after 7 years when I traded it for a 13 TDI SportWagen as I wanted a diesel. Only one that did not last that long was an 89 Golf GL which was in an autobahn accident after I moved to Germany to work at a computer company in Munich in 91 and took it with me and ended up in the middle of a massive 64 car pile up in the fog. Hardly VW’s fault. In fact it was only totaled due to every piece of sheet metal on it being bent and needing replacement. The car itself was still very drivable and survived but the insurance costs of replacing all the exterior sheet metal drive the repair costs over the limit.