VW tries to avert a driving ban of diesel cars with a software update for manipulated models. What is to be held?
Cover of a manipulated EA 189
Thursday, 22.02.2018
09:48 clock
No internal combustion engine ever received larger negative headlines than the EA 189, commonly known as cheat diesel. VW was caught more than two years agoto have driven two software modes in this two-liter four-cylinder TDI.
Engineers manipulated the emission of nitric oxide in such a way that the cars, while complying with the regulations, emitted far more in real traffic. Volkswagen has paid around 25 billion euros to date for penalties, recalls, buybacks and repairs. No one knows at this time whether the matter will be settled. As before, collective actions by shareholders amount to billions.
In the USA, Volkswagen, Audi and Porsche have withdrawn all their diesel models from the market. In Europe and the rest of the world, the engines in question were usually fitted with new software, some of which also added or replaced smaller hardware parts. About 90 percent of this work is done. The rest should be off the table this year. And then? All good? From VW’s point of view, yes.
Experts and politicians disagree. “You will not be able to solve the problem with just a few clicks of the mouse”, zanted for example the then Green party leader Cem Özdemir in August following the Diesel summit in Berlin. Customers in turn complain about problems after the update, including with particulate filters and exhaust gas recirculation.
The ADAC demanded recently a major hardware retrofit of diesel vehicles of the Euro 5 emission standard. Among them would fall from the VW “flashed” vehicles, as the manufacturer calls the software update. Hardware retrofitting with a so-called SCR-Kat, which converts the dangerous nitrogen oxides by means of urea (AdBlue) into harmless nitrogen and hydrogen, are much more effective, according to motor club, In tests, they reduced nitrogen oxide emissions by up to 88 percent. By contrast, software solutions should only bring about 25 to 30 percent. VW – as well as the rest of the industry – reject hardware solutions, mainly because of the higher costs.
SPIEGEL ONLINE had the opportunity to have the new software explained at VW in Wolfsburg.
What should the new software according to VW cause?
Software updates are not uncommon in the life cycle of a modern car. Similar to smartphones, programs run better or offer more content. In order not to lose the type approval required for the operation of the vehicles, the affected engines had to have the same power after the update, the same torque and were allowed to have no worse noise behavior or higher consumption. It was also checked which engine control strategies were used by the successor engine EA 288 (Euro 6), or could be adopted.
Despite these measures, there are doubts about the effectiveness: Most of the year are VW models that have undergone an update, not clean on the road, says the German Environmental Aid (DUH). The association had sued inter alia at the Administrative Court of Dusseldorf for a withdrawal of the operating license of the vehicles. As an argument, the DUH stated that VW still use defeat devices. The lawsuit was dismissed but the court allowed the leap review. According to DUH, the emission control of the corresponding models will be reduced at temperatures below 15 degrees. The so-called thermal windows are justified by the manufacturers with the protection of the engine.
How many cars are affected?
Worldwide, there are 10.7 million vehicles from the Group, across Europe 8.5 million, in Germany 2.5 million. Around 500,000 were in the US, where the exhaust gas manipulation flew open. At the VW brand there are 5.6 million cars, 2.4 million include Audi, 1.2 million Skoda, 0.7 million seats and 0.8 million come from VW commercial vehicles.
What changes?
One of the most important components of the diesel engine is the high-pressure injection. As before, it remains after the update in a so-called pilot injection. It is used to reduce too much excess oxygen in the combustion chamber and thus to make the inflammation process “softer”. The pilot injection “warms up” the diesel-air mixture, which reduces the level of raw nitric oxide emissions. Pleasing side effect: The “nailing” is mitigated, the engine is quieter.
The main injection was reprogrammed. It is now milliseconds earlier with a shift towards TDC (top dead center of the piston) and is reduced in quantity. Consumption goes down accordingly, but it also means less power. The whole thing is compensated with an attached post-injection. It should cause soot particles to burn in the cylinder. In addition, there is a small look-up of torque due to the downstream injection, so that at the end the performance is the same as before the update.
The maximum injection pressure of 1,800 bar is retained for the EA 189. In the frequently driven partial load range, the pressures are between 600 and 1,200 bar. They were raised slightly. Increasing the injection pressure as well as the downstream injection, among other things, ensure that the engine can drive with higher exhaust gas recirculation rates and that the nitrogen oxides (NOx) remain in a specific window – even in colder outside temperatures. Previously, a second mode was driven here. Although he kept the soot particles lower, but sent NOx in much higher amount to the outside.
Do the injectors suffer?
VW says no. In the case of the injectors, the engineers exclude a major wear caused by the pressure increase in consultation with the suppliers Bosch, Conti and Delphi and after extensive testing. On the other hand, engine expert Stefan Carstens, managing director of EngineSens Motorsensor GmbH in Viernheim, has doubts: “The magnetic injectors are, after all, moving spring-mass systems that suffer rebound and are subject to higher wear as a result of multiple injection Test results from VW also reflect the customer’s everyday life. “
What about the soot particle filter?
The new software allows the EA 189 less nitrogen oxides, but in certain operating areas, especially in the part-load range with low speeds (city and short-distance traffic), emit more soot particles. The latter must first be caught by the filter. If a certain degree of saturation is reached here, the particles are burned. VW warrants that combustion will not damage the particulate filter (DPF) as the temperature does not exceed a critical level. This is to ensure that the DPF can burn soot virtually indefinitely without prematurely wearing out.
The particle filter, however, burdened with another thing: ash. It arises from the combustion of engine oil and can not be avoided in certain quantities. Since the ashes can not be burned in the aftermath nor at all, the filter is eventually full and loses its effect. He should at least keep 180,000 kilometers at best in Volkswagen. Bestfall means: Only “low-ash” engine oil approved by VW may be used. Some cheap supermarket oil can prematurely kill the DPF. Therefore, it is difficult for Volkswagen to judge whether older ash EA-189 engines with high mileage had no ash damage. If, for a short time after the software update, the warning light in the cockpit suddenly lights up, this naturally means for the customer that everything was due to the update. Disputes like these exist, VW admits. It tries to solve the problem on goodwill.
Another problem could arise according to engine expert Carstens at the turbocharger. If the added particulate filter generates too much back pressure in the exhaust gas stream, this will overload the loader excessively. Premature failures are the result. “We are increasingly seeing clogged DPFs cause turbocharger damage on vehicles with high mileage, mostly from 200,000 kilometers.”
Which components are still affected?
The exhaust gas recirculation valve controls, among other things, the acoustics of the engine and its heating behavior via the amount of exhaust gas diverted into the combustion chamber, and it influences the amount of nitrogen oxides and soot particles. Because it also always comes to unburned hydrocarbons in the combustion chamber, the valve for the exhaust gas recirculation tends to stick – the expert speaks of “sooting”. Internal tests, each lasting more than 200 hours, showed no significant differences compared to before, according to VW. Despite the higher load on the valve due to partly more circuits in the partial load range and longer valve strokes, the respectively weighted amount of soot was at the same low level. “Affected by the ‘sooting’ is not only the exhaust gas recirculation valve, but also the entire line and the EGR cooler,” says Carstens.
What might sound outlandish for outsiders perhaps silly, just rewrite a computer program, has proven to be a mammoth task in the group, it says of VW. Volkswagen had to reprogram hundreds of new software for every brand in the group and for every model in which the EA 189 was installed. 296 variants were eligible. On top of that. Matching the cars had to be found. In total, the group bought back around 1,000 vehicles. 750 concerned only the VW brand. Partly special engine variants from Russia were brought back.
Parallel ran the programming and the subsequent test runs. Work was and will be on all days, around the clock. No engine test bench, neither in the factory nor rented externally, was only one minute unoccupied. It took tens of thousands of hours to evaluate millions of results. These laboratory measurements were followed by hundreds of thousands of kilometers of comparison tests. Dangers became with both Softwares, new and old, always in the Vierkonvoy and in the constant change. The drivers were not allowed to know whether the old or new software was in the control unit.
As much as Volkswagen is now trying to make amends and as gigantic as the effort is, the question remains as to why one has not previously made the programming in such a way that the nitrogen oxide emissions would always have remained below the required values.