Diesel Particulate Filter
The TD6 has a Catalytic Converter but no DPF - you cant use one if your country still uses high sulphur content fuel as this will destroy the filter.
There are several types of filter and I think performance will depend on which you choose. Some are disposable and I think these are the cheapest and most detrimental to your engine performance. The more expensive ones work on the same principle of the catalytic converters and actually burn the soot again (just so that you cant see it any more and instead of the soot falling to the ground you just breathe it in!). These are more expensive, and actually require the engine to go through a cycle of letting more oxygen through the exhaust to allow the cat to heat up sufficiently. This has to be designed at factory so is not an option.
Interestingly, the Petrol system uses the secondary air injection pump to pump oxygen into the cats on cold start up (when emissions are at their worst). This causes an exothermic reaction - similar to the after burner effect - although only to a mere 800C!
For its size, the 4.4 is a very efficient and clean running engine in terms of un-burnt fuel and hydrocarbons! ![](https://farm1.staticflickr.com/484/20426367072_c590738d20_z.jpg)
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