DPF Regeneration - when and how long does it take

malcolm210

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As there is very little on the subject of when and how the DPF (Diesel Particulate Filter) system works in the car handbook I thought it worth posting a comment on my experience with the 642 V6 350cdi engine as it may be of help to those who haven’t owned a modern diesel and have no experience with a DPF system

The DPF system consists of a particulate filter unit built into the exhaust system after the catalytic converter which traps soot particles before they can be released into the atmosphere and is classed as EU5 compliant. There are two pressure sensors, one fore and one aft of the unit to transmit the pressure differential to the main ECU which then determines when a regeneration needs to take place (generally every 400/600 miles), failure to do this would mean the filter would become clogged with soot, bring on the EML and put the engine into limp mode. The regeneration itself is forced by fuel being directly injected into the DPF unit to burn the soot off the filter you may see a tell tale sign of tar spots inside the exhaust tips which is the only visible physical by-product

indications of when a regeneration is taking place are a rise in tickover speed at standstill (mine tends to sit at 800rpm), increased engine temperature (due to the extra fuel injected into the exhaust system), a change in the exhaust note and quite a lot of residual heat build up under the car (quite noticeable when you open the front doors and step out)

As is often stated the car will require a longish run every couple of weeks or once a month if not too many short journeys are taken. As an example my car did a regeneration this morning and it took 15 miles to complete the full regeneration, about 6/7 of those were the engine warm-up phase, a regeneration won’t occur until the engine temp gets up to a minimum of 80C degrees, and the other 8/9 miles were the regeneration taking place. If possible I will add a few miles onto a journey if I sense a regeneration taking place until the unit is purged of soot

As I understand it there are two types of regeneration, passive and forced. The passive type relates to the car being used for frequent long journeys in which case there won’t be any noticeable indication of regeneration taking place as the higher temperature in the exhaust system burns the soot in the filter naturally. The forced regeneration is used when the car tends to be used for frequent short/medium journeys and relates more to para 3

Hope this helps and if anyone wishes to comment or correct please feel free as I’m only relating my understanding and experiences from 2 years of ownership
 

Ductman

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A further sign it has been regenerating is a smell rather akin to burning rubber if you stop the car, step out and walk around the back by the exhaust outlets.
 

umblecumbuz

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And with dpf regeneration, I learned the hard way on Malta never to park on scrubland.

It's so easy to start a fire under the car with potentially disastrous results, both to the car and the neighbourhood!
 

Headhurts

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I have always wondered why the car does not indicate a regen inside the cabin.

I have all manner of lights in mine but nothing to show a regeneration is in progress.

I purchased my car new last year and have never been aware of a regeneration going on.

Is this an industry wide thing or do some cars have an indication for the driver?

Robin


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malcolm210

malcolm210

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As far I know non of the manufacturers provide an indication that a DPF regen is taking place as far as the driver is concerned. They obviously feel that as the system operates automatically there is no need which is quite amusing really when you consider there is a dash indication/warning for just about everything nowadays

I’d prefer to know and consider it useful information, or some sort of indication of the state of the DPF would be useful as part of the onboard menu
 

Mr Filipov

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As there is very little on the subject of when and how the DPF (Diesel Particulate Filter) system works in the car handbook I thought it worth posting a comment on my experience with the 642 V6 350cdi engine as it may be of help to those who haven’t owned a modern diesel and have no experience with a DPF system

The DPF system consists of a particulate filter unit built into the exhaust system after the catalytic converter which traps soot particles before they can be released into the atmosphere and is classed as EU5 compliant. There are two pressure sensors, one fore and one aft of the unit to transmit the pressure differential to the main ECU which then determines when a regeneration needs to take place (generally every 400/600 miles), failure to do this would mean the filter would become clogged with soot, bring on the EML and put the engine into limp mode. The regeneration itself is forced by fuel being directly injected into the DPF unit to burn the soot off the filter you may see a tell tale sign of tar spots inside the exhaust tips which is the only visible physical by-product

indications of when a regeneration is taking place are a rise in tickover speed at standstill (mine tends to sit at 800rpm), increased engine temperature (due to the extra fuel injected into the exhaust system), a change in the exhaust note and quite a lot of residual heat build up under the car (quite noticeable when you open the front doors and step out)

As is often stated the car will require a longish run every couple of weeks or once a month if not too many short journeys are taken. As an example my car did a regeneration this morning and it took 15 miles to complete the full regeneration, about 6/7 of those were the engine warm-up phase, a regeneration won’t occur until the engine temp gets up to a minimum of 80C degrees, and the other 8/9 miles were the regeneration taking place. If possible I will add a few miles onto a journey if I sense a regeneration taking place until the unit is purged of soot

As I understand it there are two types of regeneration, passive and forced. The passive type relates to the car being used for frequent long journeys in which case there won’t be any noticeable indication of regeneration taking place as the higher temperature in the exhaust system burns the soot in the filter naturally. The forced regeneration is used when the car tends to be used for frequent short/medium journeys and relates more to para 3

Hope this helps and if anyone wishes to comment or correct please feel free as I’m only relating my understanding and experiences from 2 years of ownership

Sorry, from personal experience I will correct you on the temp. I had had in the past cut it short and resume after the car has been completely cold and also my thermostat was on its way and sitting below 80 almost all the time.

When I did cut it short and it resumed after a cold start it did it at 60 indicated temp.
 

Ductman

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The only visual indication you will get is if the ECO stop/start light goes yellow, rather than the usual green colour whilst driving - at least, it does on mine.
 
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malcolm210

malcolm210

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That’s interesting, I always turn stop/start off as soon as I start the car so it’s not something I wouldn’t see
 
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