DPF Regen Until Soot Level >8g

[Jubba155]

Hi there! New to the Forum, I hope you can help

I think a bit of a preface needed here: I'm new to modern diesels and DPFs so unsure what to expect. I purchased my van (2017 T6 STN BM TDI 2l 150bhp) a few months ago and noticed that just about every drive it was in a state of Active Regen, often bringing up the DPF light eventually. I grabbed a Carista, no fault codes, ever. Got the local garage to look at it because something felt odd about this. After a spend of nearly £1000 in diagnostics and contacting multiple garages the van had had work done historically, nobody could find a thing wrong at all.

Since then I have plugged in Carista every journey to see whats happening live. Seems that the van never passively regens. Once hits 24g soot will start active regen (normal). However, it will constantly kick back in to an Active Regen until soot is below 8g, no matter what the current level is. Currently sitting at 8.9g and I know it will start regen again as soon as I'm underway! Is this normal? It seems a bit silly.. why wouldn't it go 'well that drive got you down to 11g, that'll do until its 24g again'.

Pre-empting the short journeys question- I do a mix, anything from 30mins to 2hrs and usually on motorways. I've tested to see how long it takes to go from 24g to >8g on the motorway and its looong, about 1.5-1.75hrs. Which is why most of my journeys don't complete the regen..

Question is- is the ECU behaviour normal? AKA wont stop regen'ing every journey until it hits a magic >8g?

 

[huw169]

No its not normal

Typically some regen at 24 down to 6, and some 30 down to 8. Mine is the latter. Depends on software version i expect.

Mine takes 10-15 mins to fully regen regardless of motorway or around town, but if i know its doing it i try to keep revs above 2000

There will be a lower threshold where if it gets below that value and you turn it off it wont start on the next journey.

It sounds like you need a proper diagnosis as the system is not working well.

 

[Jubba155]

No its not normal

Typically some regen at 24 down to 6, and some 30 down to 8. Mine is the latter. Depends on software version i expect.

Mine takes 10-15 mins to fully regen regardless of motorway or around town, but if i know its doing it i try to keep revs above 2000

There will be a lower threshold where if it gets below that value and you turn it off it wont start on the next journey.

It sounds like you need a proper diagnosis as the system is not working well.

Thanks for your response hew169!

Yeah I have been toying with the idea of taking it for a dealer diagnosis, but being £1000 down already on diagnostics and being told there is nothing wrong has left me hesitant. I didn't mention, but previous owner had a brand new OEM DPF filter fitted only 500miles before I bought it. Assume they had the same issue then gave up and sold it!

 

[mmi]

Please post "Detailed ECU info"-report (under Carista Service menu).
Has the ECU been remapped?

I've tested to see how long it takes to go from 24g to >8g on the motorway and its looong, about 1.5-1.75hrs.

I would propose to monitor temperatures along the exhaust - preferably all 4 sensors - minimum DPF input temperature.
Ideally using VCDS, or something like -

[T6_measured] Monitoring DPF regeneration, DPF condition, EGR operation

Here's another approach for T6 DIY enthusiasts - taking advantage of very popular Carista OBDII-reader device - combined with an Android app. Ingredients: T6 EU6 engine: CXEB,CXEC,CXFA,CXGA,CXGB,CXGC,CXHA,CXHB. Carista OBDII device (also other generic OBDII (ELM327) devices will work) for...

www.t6forum.com

 

[Howzat]

Question is- is the ECU behaviour normal? AKA wont stop regen'ing every journey until it hits a magic >8g?

This is normal but a 90 minute regen isn't. On the motorway that should be 20 minutes.
Try the DPF monitor app, which is pretty simple to use, to better understand what's happening. They key is to see how many miles since last regen. You should be seeing 200 miles for motorway driving, less for urban. If a brand new DPF is clogging up quickly then the engine isn't running right. How is oil usage?

 

[Jubba155]

Please post "Detailed ECU info"-report (under Carista Service menu).
Has the ECU been remapped?

I would propose to monitor temperatures along the exhaust - preferably all 4 sensors - minimum DPF input temperature.
Ideally using VCDS, or something like -

[T6_measured] Monitoring DPF regeneration, DPF condition, EGR operation

Here's another approach for T6 DIY enthusiasts - taking advantage of very popular Carista OBDII-reader device - combined with an Android app. Ingredients: T6 EU6 engine: CXEB,CXEC,CXFA,CXGA,CXGB,CXGC,CXHA,CXHB. Carista OBDII device (also other generic OBDII (ELM327) devices will work) for...

www.t6forum.com

Thanks, I'll try to do this on my next run

 

[Jubba155]

This is normal but a 90 minute regen isn't. On the motorway that should be 20 minutes.
Try the DPF monitor app, which is pretty simple to use, to better understand what's happening. They key is to see how many miles since last regen. You should be seeing 200 miles for motorway driving, less for urban. If a brand new DPF is clogging up quickly then the engine isn't running right. How is oil usage?

It can go about 150-200 miles to reach 24g for regen, soot seems to collect around 0.1g every couple of minutes urban (very roughly) and slower on motorway.

Engine seems OK, starts and runs fine. Actually its a brand new engine installed about 12k miles ago by previous owner (as well as clutch, flywheel, belt & turbo). Oil however.. I noted oil was high when I checked after purchase. I put this down to previous owner perhaps switching off engine during regen too many times. Had oil and filter change to be safe. I check regularly now for changes in oil level, but seems to be static. There was a slight leak on the turbo feed, which I just got repaired. One thing that does worry me is that I do occasionally get 'oil service' notification on the dash (notification, not warning). I tend to reset it as definitely doesn't need changing again.