DPF Regen?

[tam87]

Apologies if there's a million different threads on this, but almost everyday so far this week the car has went into what I think is a DPF regen. The revs will sit slightly higher on idle and the car actually feels more responsive, however being a taxi most of the journeys are short and and slow speeds. So I was just wondering if this is normal?

[silver1011]

If the journey's are short then the DPF will be struggling to complete a regen, this is probably why the RPM is always high, it is constantly trying to complete.

 

After so many attempts eventually it will give up and bring on the DPF warning light. This is the car telling you it needs your help to finish the regeneration. This is when you need to take it for a longer run.

 

A high RPM doesn't only mean a regen though, when the engine is cold, when the battery drain is high, or the outside temperatures are low and you are pulling more heat into the car than the engine can create the RPM will increase to compensate.

[tam87]

Earlier tonight the revs sat quite high for a good half hour, I had the engine on the whole time and there was a slight burning smell when I got out of the car at one point. So far no warning lights have come on

[meb90]

If no warning lights have come on, then I wouldn't worry too much. But as above, a longer run or two probably wouldn't be a bad thing, and will be needed if the light comes on. Mine does smell a bit during a regen, but it has got better with age.

 

As far as I'm aware the car won't regen when just idling as the exhaust won't get hot enough.

[Gomezz]

My Scout was doing regens even after long motorway runs never mind short runs, driving me nuts.

In November it had it's first service and I think I have heard it regen once since!!

Maybe there was a fault that was spotted at service and put right? my driving habits haven't changed.

[Auric Goldfinger]

My Tdi Vrs ofter does a regen after a motorway run. I think the problem is Low revs in 6th at motorway speeds and the draft going under the car keeps everthing cool underneath.  I now drop the gears into 4th for the last few miles home which keeps the revs up and warms the filtre up to regen temperature. I drive around town in low gears which I think also helps the DPF

Edited 10 December, 2015 by Auric Goldfinger

[silver1011]

Earlier tonight the revs sat quite high for a good half hour, I had the engine on the whole time and there was a slight burning smell when I got out of the car at one point. So far no warning lights have come on

 

The car is trying to maintain heat in the exhaust system in the hope you'll set off and generate enough heat through normal driving to complete the regen.

 

Most cars don't sit on tickover for long periods (I assume you are in the taxi rank / queue?).

 

As mentioned if the DPF light hasn't come on then the car is happy enough, ignore it for now.

 

If you do get the chance though, next time the RPM is high, take it for a 5 minute run at speeds over 40mph and next time you stop the idle should return to normal.

[Skodev]

It was my understanding that the DPF regen can be completed even once the engine has been switched off. There have been a couple of occasions where once I've left the car, I have a noise which sounds like the cooling fans (but isn't) and this is when I've arrived home mid regen. Lasts a few mi Utes then shuts off. I also believe that the regens may be set to a slightly keener setting given the issues early DPF equipped engines suffered from. I'd say it's perfectly normal behaviour and short of purposely going for the odd motorway blast, I'd not worry provided no warnings are apparent.

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Edited 10 December, 2015 by Skodev

[littleade]

Page 56 on deals with regens on earlier CR engines but will be applicable to the mk3 too

 

 

http://www.natef.org/NATEF/media/NATEFMedia/VW%20Files/2-0-TDI-SSP.pdf

[littleade]

It was my understanding that the DPF regen can be completed even once the engine has been switched off. There have been a couple of occasions where once I've left the car, I have a noise which sounds like the cooling fans (but isn't) and this is when I've arrived home mid regen. Lasts a few mi Utes then shuts off. I also believe that the regens may be set to a slightly keener setting given the issues early DPF equipped engines suffered from. I'd say it's perfectly normal behaviour and short of purposely going for the odd motorway blast, I'd not worry provided no warnings are apparent.

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This is more likely to be the safety feature built in to cool the dpf down when a regen is interrupted as it gets much hotter than usual when doing a regen

[Gadget007]

I have hooked up a Bluetooth obd adaptor and using the torque app on my phone I have watched the exhaust gast temp (egt)

Normal driving the egt sits around 250-300C (at constant speed, goes higher on acceleration) at idle it drops to just under 200C. When doing a DPF clean @110kph the temp goes to 680C for around 15 min and I see the instantaneous fuel consumption increase by about 1.5l/100km, and I can hear a slight change in engine note when it does this.

At worst it does one regen per tank ( I get approx 850+ km per tank). But normally I would have it happen every second or even third tankfull.

Do the car a favour and take it for a run down the motorway on a regular basis, not just for the DPF, can give the battery a boost and may help prevent carbon build ups in the engine.

[Skodev]

This is more likely to be the safety feature built in to cool the dpf down when a regen is interrupted as it gets much hotter than usual when doing a regen

Ah ok. You know what, whatever it is, so long as it continues to go well, start first turn of the key, not display warning lights and put a smile on my face, it'll do for me.

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[silver1011]

Yeah as mentioned the fans running after the engine is turned off is to cool the exhaust down as quickly as possible. Imagine being in Southern Spain and parking on a patch of long, crispy dry grass, which is touching the exhaust.

Spontaneous combustion!

[Skodev]

My old golf had a heat shield under the cat to stop this.

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[Skodev]

Admittedly I didn't try this in Southern Spain though. Haha!!

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[andyvee]

It was my understanding that the DPF regen can be completed even once the engine has been switched off. There have been a couple of occasions where once I've left the car, I have a noise which sounds like the cooling fans (but isn't) and this is when I've arrived home mid regen. Lasts a few mi Utes then shuts off. I also believe that the regens may be set to a slightly keener setting given the issues early DPF equipped engines suffered from. I'd say it's perfectly normal behaviour and short of purposely going for the odd motorway blast, I'd not worry provided no warnings are apparent.

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The noise you hear is the cooling fans.

 

A regen can only happen with the engine running.

 

As others have said, motorway driving is not the ideal conditions for a regen unless you drop down a gear or two - the revs are too low and the cool air flow cools the exhaust too much.

 

The system on the O3 is very sophisticated, don't worry about it and let it do its thing. If the light comes on, go for a motorway run in 4th at 60mph or so to get everything nice and hot.

[littleade]

I have hooked up a Bluetooth obd adaptor and using the torque app on my phone I have watched the exhaust gast temp (egt)

Normal driving the egt sits around 250-300C (at constant speed, goes higher on acceleration) at idle it drops to just under 200C. When doing a DPF clean @110kph the temp goes to 680C for around 15 min and I see the instantaneous fuel consumption increase by about 1.5l/100km, and I can hear a slight change in engine note when it does this.

At worst it does one regen per tank ( I get approx 850+ km per tank). But normally I would have it happen every second or even third tankfull.

Do the car a favour and take it for a run down the motorway on a regular basis, not just for the DPF, can give the battery a boost and may help prevent carbon build ups in the engine.

 if your car is the same as in the link I posted above it'll do a distance regen every 750-1000km if no successful regen has taken place under the other options so most likely it's "done 1" but you've not noticed. In the 3 years I've had mine during the 16k miles I can count the number of regens I've noticed at less than 10. I just let it get on with it, as long as you're not continually doing short journeys there is nothing to worry about.

[Dempsek]

Puts tin hat on.

 

You need to be aware a DPF is a servicable item - page 68 of the liked document - also viewed as life of car item 12000 or 10 years.

 

"The enhancement of the exhaust after-treatment

system with a NOx storage catalytic converter

requires the introduction of new regeneration modes

to ensure NOx conversion throughout the storage

unit’s service life."

 

Have a look here http://www.myturbodiesel.com/1000q/vw-jetta-tdi-golf-dpf-filter.htm.

[gm73]

I’d like to add to this thread that I’ve done 142k in my MK3 1.6 CR TDI and experienced countless regens and never once had the light go on. Length of regen seems to coincide with ambient temperature and engine temperature. 

[ChoonDoode]

20 minutes ago, gm73 said:

I’d like to add to this thread that I’ve done 142k in my MK3 1.6 CR TDI and experienced countless regens and never once had the light go on. Length of regen seems to coincide with ambient temperature and engine temperature. 

 

what's your normal trip length?

[gm73]

9 hours ago, tunedude said:

 

what's your normal trip length?

Forgot to mention that my car is a taxi too. Mostly door to door journeys with the occasional motorway trip thrown in.  Usually regens once a day or every 100/150 or so miles.  

[CCTaylor]

On 10/12/2015 at 10:08, silver1011 said:

 

The car is trying to maintain heat in the exhaust system in the hope you'll set off and generate enough heat through normal driving to complete the regen.

 

Most cars don't sit on tickover for long periods (I assume you are in the taxi rank / queue?).

 

As mentioned if the DPF light hasn't come on then the car is happy enough, ignore it for now.

 

If you do get the chance though, next time the RPM is high, take it for a 5 minute run at speeds over 40mph and next time you stop the idle should return to normal.

The only thing to add to the final paragraph is: keep the revs above 1500. 40mph in top gear is as helpful for the regen process.

[KarlO3V5]

My 184 is the same. Can feel a bit different after a regen.

 

I use the VAG DPF app to monitor it - more on that here https://www.hypermiler.co.uk/dpf-diesel-particulate-filter/vag-dpf-review-andriod-vag-dpf-monitor-app

 

Also check our this page about the Mk3 VRS DPF https://www.hypermiler.co.uk/dpf-diesel-particulate-filter/skoda-octavia-iii-2013-diesel-particulate-filter-dpf-owners-manual-regeneration-faq

[Gmac983]

On 10/12/2015 at 08:02, Auric Goldfinger said:

My Tdi Vrs ofter does a regen after a motorway run. I think the problem is Low revs in 6th at motorway speeds and the draft going under the car keeps everthing cool underneath.  I now drop the gears into 4th for the last few miles home which keeps the revs up and warms the filtre up to regen temperature. I drive around town in low gears which I think also helps the DPF

 

Wow! You are brave making this comment on a dpf thread! 

I have suggested similar on other dpf threads here based on my own experiences with a 2012 Yeti 2.0tdi 140 and also with my Grand Picasso airdream hdi. In both instances I was advised by main dealer techs to drive to handbook recommendations (similar as you say above) in a lower gear with increased revs even if no dpf light is showing as it will always help out the dpf in staying clean, a perfectly logical thing to do I thought. 

Other opinionators on those other dpf threads shot me down like a burning spitfire for suggesting such a thing. 

Edited 26 October, 2019 by Gmac983

[benterrier]

My 18 plate 2l TDI has done 12k. I'm interested in keeping an eye on the dpf soot levels and regens. Looking at Karl03V5 links above the Carista elm 327 dongle paired with App VAG dpf pro or free would be the way to go. I've not used anything like this before and would appreciate any advice.

Edited 26 October, 2019 by benterrier
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