Hi all, 

 

I've got the vag dpf app and trying to figure out the optimum driving style to achieve passive regen? 

 

I've driven for a while and only once did the symbol turn red and show at over 380 degree, soot level is 75 % full. Should this mean the MG per mile go negative and start burning soot? It was showing around 50mg per mile still? To get that I drove from 0 to 70 off a roundabout to dual carriageway very hard! It shot up, but when I stayed at 70 temp immediately dropped. 

 

Currently doind an active regen every 100 miles which seems very frequent? I do short trips 4 days and long trips 1 or 2 days a week?! 

 

Thanks for any advice 

How long are the long trips? Really doesn't sound like you are doing enough to get it up to temperature for long enough.

For what it's worth I had a 2.0 tdi estate for 3½ years and the light didn't come on once.

I find it difficult to believe it is possible in the UK driving environment.

An active regen generates very high temperatures (400+ degrees) to burn off the collected carbon.  Might be possible at Autobahn speeds or towing a heavy trailer/caravan up a long steep hill but otherwise modern vehicles use a fraction of their available power to maintain motorway speed limits so exhaust temperatures would never get hot enough.

 

My personal opinion is that long runs enable low soot generation so what is thought of as a passive regen is just enabling extended periods between real regens.

 

I will be quite happy to be proved wrong

 

You don’t have drive hard for passive regens to happen. Car needs a steady speed at 1800+ rpm or something like that, fuel above 1/4 tank, coolant above 75 C and driving for longer time in order to allow the exhaust to reach the required temperature(can’t remember how much exactly).

Those conditions which are usually met on highway driving.

 

Mine does it at around 45-60 minutes of highway driving.

 

But most of the time car does active regens due to city driving and like @MarkyG82 I’ve never seen the DPF lamp on even though it does regen on every 100-150 miles.
 

Just leave DPF to finish the active regen when possible and change the oil frequently. Don’t think about it much  

My longer trips are at least 45 minutes usually. But I agree it does seem hard to get to temps required. I also agree that I could clearly see the longer trip was accumulating much less soot and so just extending the time between active regen. We'll I'm at 90 per cent soot now and about to make a 40 min drive, so it'll be the first time I see a regen while driving I assuming! (only just got the app!) 

 

I do think I worry about these things too much but at the same time I find it interesting Learning about it! 

 

Does anyone know what a good number is for the MG per mile of soot? I assume the faster constant speeds get low levels? Sat in traffic yesterday and I saw 300mg per mile, then steady speeds I saw avg 60mg I think 

I think 45 mins is on the limit. Especially when only doing short trips in the week. I can't remember how long the regen itself takes but I think you'd need c.45 mins of high temp driving to finish it. Maybe dropping a gear at cruise will help?

Whilst passive regens will undoubtedly burn off soot unfortunately the emissions fix software does not take them into account at all and will still regen as often as it is based on calculated rather then measured values.

 

If you use VCDS you will see the measured soot loading (calculated from the DPF differential pressure sensor) drop but the calculated will continue to rise and it will regen when its kidded itself there is 22G of soot or whatever the threshold is even though the measured value might be 3g in my case.

 

I have set off on a 1000km motorway and autoruote journey towing a barn door fronted trailer loaded to 3 tonne, it was pretty much wide open throttle most of the time and 100% on any incline, you could not get better passive regeneration conditions yet the poxy thing did 4 active regenerations during the journey and when I arrived at my destination the fans were running interrupting a 5th, VCDS showed 2g of measured soot.

 

All my journeys that week were a little less than 20kms but it was winter so cold starts, every journey was a started and failed regen, the car was trying to regen every time I drove it.

 

That was the final straw, I paid to have the emissions fix rolled back and since then I have been aware of only one active regen when I stopped, it never reaches the threshold as I have an EGR emulator/simulator and the software now accounts for the passive regens, it does a default regen every 1000 kms I believe.

Edited 13 May, 20233 yr by J.R.

Interesting! Luckily I haven't had the fix, my engine wasn't affected! I did 30 min this morning, the regen started the minute I got in, 3 minutes in I was doing a steady 60 and at 600 degree by 5 minutes. The regen took 16 minutes according to my app, went from 24g down to about 5. 

 

Strangely vag dpf wasn't showing soot mass measured, now it is just appeared? Is that because I've done 1 regen with the app I wonder? Anyway I can compare that to the calculated now. Be interesting! 

My 2.0 Tdi (march 2016 no Ad Blue but euro 6) does active regens every 250-300 miles however drive, which is actually reassuring as I know its doing its thing to keep the DPF in shape (I have put 45k miles on this car since I began its ownership), 

 

I have VCDS and my data checks always sees it reach around 24g measured at the time an active regen is requested, once its finished its always down to around 5-10g. I frequently put 50-80 miles per trip during the week but not at high constant speeds so it reaches the request again but the frequency is the same. 

 

My oil is changed at 10k miles without fail and DPF Ash level is around 30g (from memory of last VCDS check might be a bit higher) and its now at 90k miles. 80gram is the full limit for these VAG DPF's, so the hypothesis is around 150-200k mile before new DPF, but of course it will vary car to car. 

 

I would tend to agree with comments on not to worry about it too much and always let an active regen finish if you can, its quite obvious as you know when the Rev's increase to 1000rpm. VAG DPF is certainly useful to see the values to reassure yourself of its condition/behaviours. 

 

 

15 minutes ago, paulski said:

My 2.0 Tdi (march 2016 no Ad Blue but euro 6) does active regens every 250-300 miles however drive, which is actually reassuring as I know its doing its thing to keep the DPF in shape (I have put 45k miles on this car since I began its ownership), 

 

I have VCDS and my data checks always sees it reach around 24g measured at the time an active regen is requested, once its finished its always down to around 5-10g. I frequently put 50-80 miles per trip during the week but not at high constant speeds so it reaches the request again but the frequency is the same. 

 

My oil is changed at 10k miles without fail and DPF Ash level is around 30g (from memory of last VCDS check might be a bit higher) and its now at 90k miles. 80gram is the full limit for these VAG DPF's, so the hypothesis is around 150-200k mile before new DPF, but of course it will vary car to car. 

 

I would tend to agree with comments on not to worry about it too much and always let an active regen finish if you can, its quite obvious as you know when the Rev's increase to 1000rpm. VAG DPF is certainly useful to see the values to reassure yourself of its condition/behaviours. 

 

 

 

I'm assuming you do much longer journeys than me, or is it possible engines are set to different regen limits? I've read a fair few posts saying its normal at around 100 miles to regen. 

 

I also now can't find soot mass measured, the box on vag dpf has disappeared and I don't understand  where its gone! 

 

You have some healthy sounding figures, I'm on 29g oil ash but have only 65k miles. 

 

You're right, need to stop worrying but it's typical the regens happen on my short journeys and I don't have time (and don't really think I should have too ha) to sit in a car for 15 minutes waiting! That's the bit that worries me, as it keeps trying every trip and I interupt each time which I know isn't ideal. Just hope it times itself and happens on my long jour eys like today! 

 

On 13/05/2023 at 01:06, Gerrycan said:

I find it difficult to believe it is possible in the UK driving environment.

An active regen generates very high temperatures (400+ degrees) to burn off the collected carbon.  Might be possible at Autobahn speeds or towing a heavy trailer/caravan up a long steep hill but otherwise modern vehicles use a fraction of their available power to maintain motorway speed limits so exhaust temperatures would never get hot enough.

 

My personal opinion is that long runs enable low soot generation so what is thought of as a passive regen is just enabling extended periods between real regens.

 

I will be quite happy to be proved wrong

 

New cars will Happily regen at speeds of 30mph now! It’s nothing to do with engine speed and load, the car will create its own load through the auxiliary components if required and to increase temperature it uses a mix of glowplugs, post fuel injection and throttle control in the exhaust 

On 13/05/2023 at 22:30, paulski said:

DPF Ash level is around 30g (from memory of last VCDS check might be a bit higher) and its now at 90k miles. 80gram is the full limit for these VAG DPF's, so the hypothesis is around 150-200k mile before new DPF, but of course it will vary car to car. 

 

On 13/05/2023 at 22:52, SkodaNewb said:

I'm on 29g oil ash but have only 65k miles. 

 

Please note that any correlation between these figures and the truth is purely coincidental.

 

It is not a measured value but a calculated one based on milligrams per km or 100kms, you can even alter the parameter in VCDS so that it rises more slowly, also you can tell the ECU through VCDS that a new DPF has been fitted and it will reset the oil ash figure to zero, I did this on mine, even the measured values should be regarded with scepticism unless you regularly do an adaptation of the DPF differential pressure sensor, each time I do mine the offset correction value alters.

 

On 13/05/2023 at 22:30, paulski said:

I have VCDS and my data checks always sees it reach around 24g measured at the time an active regen is requested

 

Measured or calculated? With the EU5 emissions fix software it triggers on calculated and they altered the value of the constant making the calculated value rise much quicker which is the reason for the regens at 100 miles, maybe on your EU6 engine they have sorted things out.

 

A vehicle never able to complete a regen and which initiates one on start up before the water and oil temperature are at the required threshold is one that has serious problems and will be wearing the bores and diluting the engine oil, either the DPF is clogged with oil ash which cannot be removed during a regen or there is a problem with the DPF sensore and the ECU thinks it is clogged.

 

Its time to look up from your phones and the DPF app and take in what is happening in the real world with all the senses that god gave you including that of reasoning.