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NOx Adsorbers

14 February 2005

German manufacturers believe the D-CAT emission system by Toyota has serious durability problems and fails to deliver the required emission performance, reports Germany’s Automobilwoche. The system, featured on the Avensis D-CAT model, was said to fail to comply with Euro 4 limits after a period of operation. But Toyota says the D-CAT emission system is being continuously improved, and will be featured in the new 2.2 D-4D “Clean Power” engine unveiled at the 2004 Paris Motor Show.

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The Toyota Avensis 2.0 D-CAT was launched commercially in 2003/2004, after a field test program with 60 vehicles. Since the DPNR requires ultra low sulfur diesel, the Avensis D-CAT was introduced in selected markets where such fuels were available, including Germany and the UK. But the critics argue the DPNR system is still in the development phase, and few vehicles have been actually sold to the public. Toyota has not revealed the sales volume of the Avensis D-CAT model.

According to an unnamed Toyota supplier, the D-CAT emission system has had numerous well-known problems. In contrast to “official” measurements at the FEV, the supplier’s own tests showed that after 20,000 to 40,000 kilometers the vehicles could no longer meet the Euro 4 NOx limit. The Euro 4 emission durability requirement is 100,000 km.

Skepticism about the commercial viability of NOx adsorbers on diesel engines was also expressed by BMW development boss Burkhard Göschel, who said that the only durable solution for meeting future NOx emission standards is urea-SCR technology.

The new “Clean Power” D-4D engine will be produced by Toyota Motor Industries Poland (TMIP), a new engine plant with production capacity of 150,000 engines per year.