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The Citroën Guide Fuel Injection: Diesel engines 17
Diesel Direct Injection
I think that at this point, soot burning filters will have to be
cut out of the PDF and put in at a similar ecological section
under DI/HDI—since that is the only system that actually
makes soot burning practical, and the only system that im
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plements it.
Soot burning was experimented with a lot but was never
made practical before HDI due to a too low exhaust temper
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ature. The particle filter would need heating to a very high
temperature and that was deemed to be too dangerous.
Even with cerine additives, essentially, there would have to
be a separate small burner to heat up the filter, which is
again another system that can go wrong. HDI essentially in
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tegrates a burner by alowing post-injection, something
that is simply impossible for injection systems derived from
a classical pump due to teh timing required. I think that for
soot management it is enough to write that the smoke limit
control is vastly improved by the better regulation of the
EDC.
Other things like controlled swirl and multi-valve technol
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ogy, also pioneered by Citroën (XM 2.1 TD!) should be men
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tioned. The catalytic converter section remains unchanged.
And, of course, there should be an "In addition to the pol
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lution management implemented on mechanical injection
systems" sentence somewhere in there, since proper cold
start corrections and EGR are implemented in EDC units by
default.
