Dpf re-gen

[Kev57]

Hi everyone,
I have a 2014 A4 Avant 2.0 tdi automatic.It seems to be doing a dpf re-gen every two weeks even if I have been on a long motorway run,is this normal.The car has covered 114000 since new with full service history.
No warning lights present and drives ok.
Is there anyone out there that could put my mind at rest or is there a large bill on the way.

 

[KrisKrk]

My car was 5 years old when I got it in 2015 and had less than 78k on the clock.

After few months of ownership, it started to develop symptoms of increased rev by 100rpm, throttle response like after remap, increased temperature inside the cab and fans running like mad after the car was off.
As had no idea what it was and why, gave it for a warranty check and came back with no errors from the cpu. Nothing could be found and there was no log of anything wrong with the car.

It turned out, it was dpf regen, although I was occasionally running high rpm trips to do so but it never did it during them. These regens tend to appear approx every 2 weeks/200miles.

Heard and read that, best it is not to turn off the engine if car is in the regen mode and allow more longer trips.
It may look like the dpr has nit regenerated properly for some time and it prompts regen more often now.

New dpf is expensive and to clean it with chemicals is pointless.
You could take it out and pressure clean it from the outlet, backwards to it’s normal working flow. That apparently do more than chemically cleaned dpf’s.
This however, is (to some) pointless, as you’ll be beyter off by hutting it when you have it off the car already.

I did that with mine, egr switched off in ecu and remapped to stage 1.
Fine tune will allow a proper mix of gasses to come out so you wouldn’t leave a big pile of smoke after your set off the traffic lights.

Had no dpf regen issue again since then. That was in February this year.

As for nearly 4 year old car, you’ve covered quite a lot of miles so it may be a sign of dpf on its way to full clogg.
Dash should show you warning when it reaches 75%, if I’m not wrong.


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[Kev57]

My car was 5 years old when I got it in 2015 and had less than 78k on the clock.

After few months of ownership, it started to develop symptoms of increased rev by 100rpm, throttle response like after remap, increased temperature inside the cab and fans running like mad after the car was off.
As had no idea what it was and why, gave it for a warranty check and came back with no errors from the cpu. Nothing could be found and there was no log of anything wrong with the car.

It turned out, it was dpf regen, although I was occasionally running high rpm trips to do so but it never did it during them. These regens tend to appear approx every 2 weeks/200miles.

Heard and read that, best it is not to turn off the engine if car is in the regen mode and allow more longer trips.
It may look like the dpr has nit regenerated properly for some time and it prompts regen more often now.

New dpf is expensive and to clean it with chemicals is pointless.
You could take it out and pressure clean it from the outlet, backwards to it’s normal working flow. That apparently do more than chemically cleaned dpf’s.
This however, is (to some) pointless, as you’ll be beyter off by hutting it when you have it off the car already.

I did that with mine, egr switched off in ecu and remapped to stage 1.
Fine tune will allow a proper mix of gasses to come out so you wouldn’t leave a big pile of smoke after your set off the traffic lights.

Had no dpf regen issue again since then. That was in February this year.

As for nearly 4 year old car, you’ve covered quite a lot of miles so it may be a sign of dpf on its way to full clogg.
Dash should show you warning when it reaches 75%, if I’m not wrong.


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Ok thanks for that expected a few more reply’s? though

 

[Robarch2017]

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[Retroman]

I assume you are talking about "active" regenerations. Active ‘regeneration’ is when the ECU intervenes when the soot loading in the DPF is calculated to be 45%. The procedure lasts for about 5 – 10 minutes. Specific measures are taken by the ECU to raise the engine exhaust temperature to above 600°C, these include switching off the EGR and increasing the fuel injection period to include a small injection after the main injection. The soot particles are oxidised at this temperature.

The ECU will trigger a regeneration process, if for some reason this is aborted, ie. driver slows down, stops etc, the process will be resumed when regeneration conditions are once again met, above 60km/h (38mph). This will continue for 15 minutes.

If after 2 attempts of 15 minutes, a successful regeneration has not been possible, the loading will increase. At 50% soot loading, the ECU will continue to maintain maximum exhaust temperatures of 600°C to 650°C to cause a regeneration process. The system will try to run a regeneration process for 15 minutes. If unsuccessful, the system will repeat this process for a further 15 minutes, if still unsuccessful, the DPF light on the driver display panel will then be lit.

The soot when burnt is supposed to be transformed into finer ash particles most of which then get expelled through the filter and out the exhaust. Over time small remnants of ash build up and block the DPF. This blockage of ash cannot be removed by regens – passive, actioned or forced. How long does this take – who knows – but generally thought to be over 100,000 miles.

 

[Kev57]

I assume you are talking about "active" regenerations. Active ‘regeneration’ is when the ECU intervenes when the soot loading in the DPF is calculated to be 45%. The procedure lasts for about 5 – 10 minutes. Specific measures are taken by the ECU to raise the engine exhaust temperature to above 600°C, these include switching off the EGR and increasing the fuel injection period to include a small injection after the main injection. The soot particles are oxidised at this temperature.

The ECU will trigger a regeneration process, if for some reason this is aborted, ie. driver slows down, stops etc, the process will be resumed when regeneration conditions are once again met, above 60km/h (38mph). This will continue for 15 minutes.

If after 2 attempts of 15 minutes, a successful regeneration has not been possible, the loading will increase. At 50% soot loading, the ECU will continue to maintain maximum exhaust temperatures of 600°C to 650°C to cause a regeneration process. The system will try to run a regeneration process for 15 minutes. If unsuccessful, the system will repeat this process for a further 15 minutes, if still unsuccessful, the DPF light on the driver display panel will then be lit.

The soot when burnt is supposed to be transformed into finer ash particles most of which then get expelled through the filter and out the exhaust. Over time small remnants of ash build up and block the DPF. This blockage of ash cannot be removed by regens – passive, actioned or forced. How long does this take – who knows – but generally thought to be over 100,000 miles.

 

[Kev57]

Thank you for that,just going to drive the car and stop worrying about it.

 

[Kev57]

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What a crock of crap!

 

[Retroman]

The video has some valid bits but as usual is overly negative about DPF problems. They’ve been the law in the UK since 2009 so approximately 50% of the new cars sold since then have had them fitted. Some of the early, rushed, pre-2009 attempts by manufacturers had teething problems like DPFs situated too far from the engine (insufficient heat) and injectors not capable of the succession of millisecond pulses capable of creating activated regen exhaust heat.

He talks about having to drive the car for an hour to activate a regen whereas VAG technical engineers talk about just 15 minutes.

He talks about air leaks downstream of the MAF causing an enriched mixture whereas in my experience it causes the opposite i.e. a lean mixture evidenced by poor cold starts and other sensors throwing “lean” error codes

 

[Owyn]

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I've seen a few of this guys videos and they are generally well worded, articulate collections of complete ********.