Excessive DPF Regeneration Octavia VRS Mk3

[littleade]

The issues of long motorway driving and DPF issues is a well known issue and covered by the AA.

 

From the AA "

AA experience

We're seeing some evidence of DPF systems failing to regenerate even on cars used mainly on motorways.

On cars with a very high sixth gear the engine revs may be too low to generate sufficient exhaust temperature for regeneration. Occasional harder driving in lower gears should be sufficient to burn off the soot in such cases."

it's rather a generic statement from what is a company that deals with all manufacturers problems at the roadside, not just Skoda-is there any evidence this actually happens to the VAG CR engines?

[Gabbo]

it's rather a generic statement from what is a company that deals with all manufacturers problems at the roadside, not just Skoda-is there any evidence this actually happens to the VAG CR engines?

 

The principal of this statement is sound though & I think pretty relevant to this thread.

Driving at steady motorway speeds doesn't create the hottest conditions for the exhaust & thus good conditions for DPF regen.

At high speeds the airflow around the car & through the engine provide a great deal of cooling reducing the DPF temperatures & probably reducing the chances of passive regen.

 

This is why people see that a regen is started when you come off the highway & back down to city speeds as the cooling effect is greatly reduced & the ECU sees this as a better opportunity to create exhaust temperature.

 

Just because the fan runs when you stop, doesn't indicate a problem, you've just interrupted a normal process.

There's no need to keep driving the car until it stops, it will automatically restart the next time you drive the car & the conditions are favourable.

If several attempts to perform a passive regen have not been succesful then an active regen should take place.

Here I would expect that it can also be performed at motorway speed as it involved injecting fuel very late so it burns in the exahust to increase DPF temperatures.

 

 

I drive 99% of the time on the highway at around 100kph for 65km each way each day (~600km per week).

Every week or so when I arrive to my parking place, the fans are running 100%.

If I happen to take a drive into town or the supermarket, the fans are also running 100% for two or three short journeys when I stop indicating the regen is still in progress.

For me this is normal behaviour.

Eventually after a few times, the regen seems to complete.

 

 

However, for the OPs problem, if it is happening every single time you stop it may indicate a problem but the dealer should be best placed to diagnose this.

[Gabbo]

it's rather a generic statement from what is a company that deals with all manufacturers problems at the roadside, not just Skoda-is there any evidence this actually happens to the VAG CR engines?

 

As a side note I think this kind of statement comes from the 1st generation of DPF engines where active/passive regens & functions like this were not so advanced.

Its similar to the first engines introduced with EGR valves which were suceptable to sticking/blocking.

Just wait until SCR systems also become common on the VAG engines....

[MarkL_eb]

My active regen came on after a 70 mile motorway journey and completely flattened the battery due to the fan running. This has happened twice. Has anyone else had this problem? 

 

[Ecomatt]

Not happened to me but if your battery is completely flat after the fans running. I would get a load test done to see if it is a battery or alternator issue. Equally I would get it scanned on vcds to see if it highlights any obvious faults.

[cheezemonkhai]

About 2000 rpm is fine to regen on a journey of a decent length.

 

I think sticking on a motorway at 70 for an hour long journey should prevent any issues.

 

If anything I would ask to have then sensors checked as maybe the pre-dpf or post-dpf Sensors are reading a bit odd and the car thinks the dpf is more full than it is.

 

If you put the revs too high then the regen isn’t as successful.

 

Also the dpf on the mk2 was well back on the exhaust so needed more heat. On the mk3 engines the dpf is much much closer to the engine and has far fewer issues. 
 

That means the information on the mk2 dpf doesn’t necessarily apply to the mk3.

Edited 6 June, 2020 by cheezemonkhai

[MarkL_eb]

Battery and alternator were fine. No faults found.i don't believe Skoda have found the fault.

[Ootohere]

@MarkL_eb   Welcome to the forum.

?

So when was your car built and how many miles has it done?

[MarkL_eb]

It's done about 54000 mainly motorway miles.  2017. I think the car is great apart from this issue.

[Ecomatt]

17 hours ago, MarkL_eb said:

It's done about 54000 mainly motorway miles.  2017. I think the car is great apart from this issue.

Have you access to vcds as it would be handy to see if it does it on a forced regen. Then you can see if it shows any unusual readings. 

[varaderoguy]

From personal experience, I had to relearn my driving style.  The VW group TDi engines need to be driven harder; but our driving styles and the way the car is geared ditate we should be less harsh.  I agree that it is heat that is needed to perform a proper re-gen.  Try dropping from 6th to 5th if a re-gen is started;  you can find that DPF's can block-up especially if at any point in their life they have done lots of slower/town driving.  I had recorse of a person who saw the DPF light on their car, ignored the problem and went off around Europe in their Octavia....DPF light didn't come back on again.

[gm73]

My car has done 164k miles and I've had the light come on once at approx 140k. Some harsh backwoods driving sorted that.

 

It's a taxi and it does a regen at least every 150/200 miles. Occasionaly it struggles to go over 35 mph whilst doing a regen but the last time that happened was ages ago since I now exclusively use higher quality fuel and add in DPF cleaner every now and then. I'd like to check the amount of soot in the filter. I've got Carista but I'm not sure it can do it.

[MarkL_eb]

I am thinking that if it's in the middle of a forced regen when you finish your journey, the dpf is hot and then the fan runs for an excessively long time and drains the battery. 

[alextz]

My car now started to do regens often.2015 VRS TDi. I have noticed that it starts them based on soot mass measured. Is it the same on yours ?

[MarkL_eb]

24 minutes ago, alextz said:

My car now started to do regens often.2015 VRS TDi. I have noticed that it starts them based on soot mass measured. Is it the same on yours ?

How can you view 'soot mass measured'?

 

[alextz]

VCDS or OBDeleven in Engine group an search for soot.

You can see both values. Calculated and Measured.

[J.R.]

My Yeti is my first ever vehicle with a DPF, I was working on it for a few months repairing the accident damage, the engine got started a lot of times but never driven anywhere, maybe a few feet backwards & forwards, several times I would leave it idling for 30+ minutes till everything was up to temperature, not sure if that was good or bad for the DPF.

 

One time the fans ran on after switch off but I didn't know what it was.

 

Then I got the DPF light which freaked me out, I had finished the repairs then so took it for a drive, within 10 minutes of the oil reaching temperature it was all over.

 

Since then like some of the others I am completely unaware of the DPF, I have never noticed a higher idle speed and the fan has never run after switch off, the vehicle got little use during the confinement and when it did it was only 2-5 mile trips, now I am back to my usual routine of 3 or 4 return trips per week of 10 miles each way, one or two of 20 miles each way and maybe 5 or more 2-3 mile trips and I have never experienced a forced regen.

 

I have VCDS and when I looked before there were thousands of parameters to check, is there a distance since last forced regen or until the next one? Any other parameters that I should be looking at? Its hard to know which ones are calculated and which ones are measured.

[SkodaAsh]

Sorry to be ignorant on this topic, but is the purpose of the Regen to just clean the turbo and how do you know it’s happening? I haven’t noticed any fan running in the 2years I’ve had my Octavia TSI RS. 

[alextz]

Only specific to TDI.

 

On the Yeti you have an older type of engine EA189. Different beast.

You can look for the mass measured soot and mass calculated soot.

[OldBoyScout]

9 hours ago, SkodaAsh said:

Sorry to be ignorant on this topic, but is the purpose of the Regen to just clean the turbo and how do you know it’s happening? I haven’t noticed any fan running in the 2years I’ve had my Octavia TSI RS. 

 

7 hours ago, alextz said:

Only specific to TDI.

 

 

Yes, as Alex says this applies (mostly) to diesel cars only and the purpose of the regen is to burn away excess soot in the DPF (Diesel Particulate Filter). Some newer petrol cars have a GPF (Gasoline Particulate Filter), but GPF regen issues don't seem to be common at present.

 

On 08/06/2020 at 21:02, gm73 said:

I'd like to check the amount of soot in the filter. I've got Carista but I'm not sure it can do it.

 

You should be able to do this with Carista using the VAG DPF app on Android. Many but not all VW group diesel engines are supported in the app, and there is a free version that you can try to see if it works for you before shelling out about £3 on the paid version that gives more detail. It works on my 2015 2.0 TDI with bluetooth Carista and a Lenovo tablet.

 

 

[OldBoyScout]

15 hours ago, J.R. said:

 

Since then like some of the others I am completely unaware of the DPF, I have never noticed a higher idle speed and the fan has never run after switch off, the vehicle got little use during the confinement and when it did it was only 2-5 mile trips, now I am back to my usual routine of 3 or 4 return trips per week of 10 miles each way, one or two of 20 miles each way and maybe 5 or more 2-3 mile trips and I have never experienced a forced regen.

 

I have VCDS and when I looked before there were thousands of parameters to check, is there a distance since last forced regen or until the next one? Any other parameters that I should be looking at? Its hard to know which ones are calculated and which ones are measured.

 

According to tech info from VW, which I have quoted on earlier threads but can't find at the moment, the active regens are first triggered when the soot content of the DPF reaches a certain level, 45% I think. Regen attempts will then continue when conditions are right until the process completes successfully, or the warning light comes on indicating that intervention from the driver is needed.

 

My driving pattern is not what might be considered ideal for a diesel engine, but in over 4 years of ownership I have never seen a DPF warning. Occasionally the fan running with a burning smell indicating interrupted regen has occurred after switching off, and occasionally I have noticed a higher idling speed indicating regen in progress, mostly when DSG is coasting in eco mode. I got the Carista and VAG DPF app to reassure myself that all was well, and have now come to the conclusion that the car will take care of the regens OK and I don't need to worry about it.

 

[alextz]

So I get this on the national/highway roads. Soot mass measured is increasing way faster than calculated.

Any ideeas? No oil consumption.