F for Jürgen Resch, managing director of Deutsche Umwelthilfe (DUH), it is A paradoxical case: 'It cannot be that because of the high levels of particulate matter in large cities, environmental zones are set up at considerable expense, into which only low-particle and low-emission cars are allowed to drive, and on the other hand the effectiveness of the exhaust gas cleaning is only pretended to be checked,' he says .
Exhaust gas testers are no longer up to date
A solid rifle aid the environmental activist receives from the testing organizations, the Central Association of the German Motor Vehicle Industry (ZDK) and the Federal Association of Automobile Service Equipment (ASA): Both the measurement method and the limit values have not kept pace with the further development of the engine and exhaust technology of the vehicles, so the unanimous opinion. Because one thing is clear: Environment and health can only be protected if the effectiveness of modern diesels with particle filters can also be reliably checked. And that is no longer possible with today's compression-ignition emissions test (AU). It is simply from yesterday and therefore for the cat. 'For years, with the knowledge of all those involved, an obviously ineffective mass investigation has been kept alive, which costs citizens money and ensures that defective vehicles drive unhindered and unnoticed on our roads,' says environmental expert Axel Friedrich, former head of department at the Federal Environment Agency.
The test values have remained almost unchanged since 1993
Because while the pollutant limit values have been massively tightened step by step in the past decades, the test values have remained for Diesel almost unchanged since 1993. The result: The gap between the two parameters is now so large that even ten-year-old Euro 3 vehicles with defective emissions control pass the test. The current state of the used measuring technology per opacimeter is to draw conclusions on the compliance with the limit value based on the opacity of the diesel smoke - this is at an opacity factor of 1.5. 'That is a good ten times as much as is registered with modern diesels,' says Hans-Jürgen Mäurer, Head of Dekra Development Technology. Even diesel without a particle filter achieved turbidity factors between 0.5 and 0.8 - well below the legal limit. 'That can no longer be conveyed,' said Mäurer.
Benchmark for carsfrom Euro 2 should be adjusted
He therefore advocates adjusting the benchmark for cars from Euro 2 to the state of vehicle technology. The so-called badge values noted on the nameplate should serve as a guide. 'These values are determined and documented as part of the type approval,' says the Dekra expert. In a second step, more precise measuring devices would have to be used that can determine the particle emissions in grams per cubic meter. These are already available today and are no more expensive than their outdated predecessors. They also passed the acid test in a field test conducted by the Emission Working Group in 2010 on over 1,000 diesel vehicles. Dekra, Kfz-Gewerbe, ASA and the technical inspection associations were also involved. 'In this joint project, modern particle measuring devices have proven that they are operational,' says Günter Afflerbach from TÜV Nord.
Car manufacturers refer to on-board diagnostics
The car manufacturers are not very impressed by the new movement to reform the AU. They refer to the so-called on-board diagnosis (OBD), which has also been checking the exhaust system for several years. 'This method is not able to identify all deficits', says Hans-Jürgen Mäurer. The intervention threshold, which triggers an error message, is about three times as high as the corresponding limit value. Antonio Multari, project manager for particle measuring devices at the manufacturer Maha im Allgäu, also explains: 'The OBD only registers the pressure difference before and after the soot filter.' Hairline cracks, signs of aging or defects remained undetected. 'The tailpipe test is also important to see what particles really come out of,' says Multari.
New particle measuring device works according to the laser scattered light method
For the Maha particle measuring device MPM 4, which works according to the laser scattered light method, approval is from the Physikalisch -Technischen Bundesanstalt (PTB) applied for. 'After the introduction of diesel particulate filters and their retrofit programs, politicians must now ensure timely control of the functionality of these systems over the life cycle,' says ASA President Klaus Burger. Only then can the emissions test fulfill its original purpose again.