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+--- Thread: What exactly is DPF (/Thread-What-exactly-is-DPF)
What exactly is DPF - Big G - 23-07-2012 10:00am
Seen a few comments about DPF and the need for the correct engine oil - which I purchased from my dealer, Castrol Edge Professional C1 oil. Just wondering what DPF actually is and if there are any specifics on it. For example I seem to remember some comments that its not best suited to short stop start trips. Have I this right at all ?
Thanks.
RE: What exactly is DPF - griff - 23-07-2012 10:18am
Diesel Particulate filters (DPF) or 'traps' catch bits of soot in the exhaust.
As with any filter (think of the bag in your vacuum cleaner) they have to be emptied regularly to maintain performance. For a DPF this process is called 'regeneration' – the collected soot is burnt off at high temperature to leave only a tiny ash residue.
Regeneration is either passive or active
Passive regeneration
Passive regeneration takes place automatically on motorway-type runs when the exhaust temperature is high. Because many cars don't get this sort of use car manufacturers have to design-in 'active' regeneration where the engine management computer (ECU) takes control of the process.
Active regeneration
When the soot loading in the filter reaches a set limit (about 45%) the ECU can make small adjustments to the fuel injection timing to increase the exhaust temperature and initiate regeneration. If the journey is a bit stop/start the regeneration may not complete and the warning light will come on to show that the filter is partially blocked.
It should be possible to start a complete regeneration and clear the warning light by driving for 10 minutes or so at speeds greater than 40mph.
If you ignore the warning light and keep driving in a relatively slow, stop/start pattern soot loading will continue to build up until around 75% when you can expect to see other dashboard warning lights come on too. At this point driving at speed alone will not be enough and you will have to take the car to a dealer for regeneration.
Thanks to the AA
RE: What exactly is DPF - Big G - 23-07-2012 02:17pm
(23-07-2012 10:18am)griff Wrote: Diesel Particulate filters (DPF) or 'traps' catch bits of soot in the exhaust.
As with any filter (think of the bag in your vacuum cleaner) they have to be emptied regularly to maintain performance. For a DPF this process is called 'regeneration' – the collected soot is burnt off at high temperature to leave only a tiny ash residue.
Regeneration is either passive or active
Passive regeneration
Passive regeneration takes place automatically on motorway-type runs when the exhaust temperature is high. Because many cars don't get this sort of use car manufacturers have to design-in 'active' regeneration where the engine management computer (ECU) takes control of the process.
Active regeneration
When the soot loading in the filter reaches a set limit (about 45%) the ECU can make small adjustments to the fuel injection timing to increase the exhaust temperature and initiate regeneration. If the journey is a bit stop/start the regeneration may not complete and the warning light will come on to show that the filter is partially blocked.
It should be possible to start a complete regeneration and clear the warning light by driving for 10 minutes or so at speeds greater than 40mph.
If you ignore the warning light and keep driving in a relatively slow, stop/start pattern soot loading will continue to build up until around 75% when you can expect to see other dashboard warning lights come on too. At this point driving at speed alone will not be enough and you will have to take the car to a dealer for regeneration.
Thanks to the AA
Thats great - many thanks for taking the time to help - appreciated.