Jump in Calculated Soot Mass

Wilts01
Posts: 7
Joined: Mon Mar 02, 2020 10:07 pm

Jump in Calculated Soot Mass

Post by Wilts01 » Mon Mar 02, 2020 10:16 pm

I have a 2011 Seat Alhambra with a CFFB engine. Recently it has been constantly trying to regenerate - or I think so since the engine fan goes to full speed for 5mins nearly every time I switch it off. Sadly the local dealer doesn't believe me so I am trying to get some evidence.

Tonight, on my usual 10 mile drive home, I set up a recording from cold. I got the attached plots for Soot Mass Calculated and Measured (plus differential pressure) - X-axis is time in seconds.
Journey Home 2020_03_02.png
Is this jump in the calculated value normal? I think that the red "regen pending" indicator came on at the same time but cannot be certain (as an aside, is this logged?).

Pointers appreciated!

Thanks

Paul

User avatar
admin
Site Admin
Posts: 150
Joined: Sun Jun 02, 2019 10:58 pm

Re: Jump in Calculated Soot Mass

Post by admin » Tue Mar 03, 2020 11:48 am

I've seen similar step when the "mileage since last regeneration" reached the maximum acceptable value. In fact, one of the protection of the DPF system is the limiting of the maximum mileage between regenerations to prevent the risk of fire in case of failure of some sensor.
Limiting the mileage, the soot mass in the filter can't reach risky values in any case.

In your case, you should understand if the mileage since last regen (this parameter is present in the app) is near 8-900 km, in this case it's normal, otherwise it's possible you have some fault the DPF system. The differential pressure sensor is probably the first you should check, because its failure happens very often.

Wilts01
Posts: 7
Joined: Mon Mar 02, 2020 10:07 pm

Re: Jump in Calculated Soot Mass

Post by Wilts01 » Tue Mar 03, 2020 11:58 am

Thanks. The distance since last regen is being reported as less than 30km. So sounds like a Sensor issue then

Thanks

Paul

User avatar
admin
Site Admin
Posts: 150
Joined: Sun Jun 02, 2019 10:58 pm

Re: Jump in Calculated Soot Mass

Post by admin » Wed Mar 04, 2020 9:01 am

Differential pressure value is available for your engine in the app, but it's not so easy to understand if the values your read are ok. You should ask to someone who own the same engine or with an expert about the DPF system.
Moreover, the diff. pressure sensor couldn't be the cause of this failure.

Wilts01
Posts: 7
Joined: Mon Mar 02, 2020 10:07 pm

Re: Jump in Calculated Soot Mass

Post by Wilts01 » Wed Mar 04, 2020 11:20 am

Thanks- I’ll ask a bit wider afield now I have the data. What I have found is that the measured value goes down dramatically if I sit on tick-over with regen happening event though the differential pressure is unchanged.

Anyway thanks again for developing such a useful app

andreim90
Posts: 5
Joined: Wed Jun 17, 2020 9:54 am

Re: Jump in Calculated Soot Mass

Post by andreim90 » Wed Jun 17, 2020 10:08 am

Hello,

Did you manage to solve the problem or find out why its happening like this?
Im in a similar situation with a Passat B8 2015 2.0tdi 150hp engine code CRLB.
I have each time a sudden and instant spike in soot mass calculated from 12-14gr (after 90-110km from last succesful regen) to 23-24gr ,and of course active regen trigered seconds later.

However i cannot see the soot mass measured field in my vagdpf with CRLB , the field is replaced with "nox sulfur charge(g)".

How did you create the graphs(x,y plots)? From the logger of vagdpf i get only an enormous .txt file and a .bck file which i cannot open.

Thanks.

User avatar
admin
Site Admin
Posts: 150
Joined: Sun Jun 02, 2019 10:58 pm

Re: Jump in Calculated Soot Mass

Post by admin » Wed Jun 17, 2020 4:13 pm

You can open the TXT file with excel and create the graph using the columns you want.

In this case it's useful to include also the "time since last regen" and "distance since last regen" to understand if the regeneration happens due to limits reached.

Wilts01
Posts: 7
Joined: Mon Mar 02, 2020 10:07 pm

Re: Jump in Calculated Soot Mass

Post by Wilts01 » Wed Jun 17, 2020 10:29 pm

Unfortunately COVID 19 has stopped my attempts to find out what is happening. My main dealer is stumped but SEAT tech support will only accept data gathered using the official SEAT software. So we were going to collect some but the the UK lockdown prevented this from occurring

Humbucker
Posts: 4
Joined: Wed Jun 17, 2020 10:24 pm

Re: Jump in Calculated Soot Mass

Post by Humbucker » Wed Jun 17, 2020 10:40 pm

Hello andreim90
I have a 2015 Passat 2.0 estate GT CRLB engine code.
Same fault as mine. It just happened about 2 weeks ago.
Noticed it re gening after 40 miles. I monitored this week and today on returning home at 40 miles it jumped from 11.39 soot mass 49% to 23.38 100% within 1 minute of driving. I had to take it on a run for a regen after. Have you been able to find the fault.
Car has done 90000 miles.
Just spent £700 on having a vacume pipe replaced.
Turns out it's a known fault. Causes hard brakes on startup and turbo actuator fault as well.

andreim90
Posts: 5
Joined: Wed Jun 17, 2020 9:54 am

Re: Jump in Calculated Soot Mass

Post by andreim90 » Thu Jun 18, 2020 8:13 am

Thank you both for replies, please post updates if you figure it out.
In my case regen is surely not happening due to limit reach in time or distance since last regen. As we speak about 60-160 km and 2-5 hours every time.

alextz
Posts: 2
Joined: Thu Jun 18, 2020 9:38 am

Re: Jump in Calculated Soot Mass

Post by alextz » Thu Jun 18, 2020 10:13 am

Hello,

Same issue here. We found 2 cars with the same problems and both have some injector values which do not seem correct. Can you check with VCDS or OBD11 for injector deviations?

Humbucker
Posts: 4
Joined: Wed Jun 17, 2020 10:24 pm

Re: Jump in Calculated Soot Mass

Post by Humbucker » Thu Jun 18, 2020 11:40 pm

Hi,
I am going to order VCDs this weekend once I get paid. Hopefully then might get some info as to why its jumping from 50% to 100% in 1 mile.

alextz
Posts: 2
Joined: Thu Jun 18, 2020 9:38 am

Re: Jump in Calculated Soot Mass

Post by alextz » Fri Jun 19, 2020 5:52 pm

It jumps because Soot Mass measured reaches the limit and to initiate a regen the ECU copies the value to Soot Mass Calculated.

Something is making out cars smoke... But no errors and no previous experience... :(

Pass15
Posts: 1
Joined: Sat Jun 27, 2020 7:05 am

Re: Jump in Calculated Soot Mass

Post by Pass15 » Sat Jun 27, 2020 8:07 am

Hello @Humbucker and @andreim90

I've got the very same car, and problem as both of you. Passat B8 from 2015, 2.0 TDI 150HP, engine code CRLB. Car has done 140000km (~90k miles) now, and since a couple of weeks, it regenerates very often, right now with less then 70km driven, while before regenerations occured in intervals of 300-600km. My ash volume is at 36.6g from a maximum of 80g, so the DPF should be still good.

With VAG DPF I could monitor, that yesterday, the soot mass calculated jumped from around 8-9g to 23,xx grams, after the ash mass measured reached 23,xx grams, and regeneration process started. After only about 70km driven...
Apart from that, my car has normal fuel consumption (~6,0l/100km or ~40MPG), and the engine runs smoothly and is powerful

I'm curious if the differential pressure sensor might be be faulty, but have to investigate on that yet.
Have you been able to find a culprit yet?

I can get access to VCDS, and will also look into the injector values, as @alextz suggested, soon.

andreim90
Posts: 5
Joined: Wed Jun 17, 2020 9:54 am

Re: Jump in Calculated Soot Mass

Post by andreim90 » Thu Jul 02, 2020 9:43 am

Hello,

I have been to the local VW dealership at the beggining of this week and explained the sympthoms of often regens(last 3 regens were at 30-60 km of city driving), and they said its indeed too often and they will look into it.
They updated the ecu software with a newer versions and i think they did also a forced regen(soot calc was at 2 gr when i took the car after 45 km from last regen done by them, usually after my active regen soot calc only gies down to 5-6 gr, so i guess they did something diferent since it was now so low at 2 gr).
They also mentioned that dpf temp sensor 3 is showing abnornal values when cold started and when contact is on but car is not started. They however told me they dont belive that is what is causing often regens.

I took the car and at 110 km since last regen(45km done by service,the rest by me in mixed condition city/national road/highway) ,the regen triggered again.

I think my problem is slightly improved,but far from solved. I will run it through another 1-2 regen cycles and then make another apointment. I alredy informed the workshop and they told me we should then change the sensor that they found faulty and see again.

I attached a picture with a graph showing my main parameters from dpf before and after VW intervention.

Thanks

PS: oil ash for me 32.9 gr
Attachments
Andrei.JPG

User avatar
admin
Site Admin
Posts: 150
Joined: Sun Jun 02, 2019 10:58 pm

Re: Jump in Calculated Soot Mass

Post by admin » Thu Jul 02, 2020 5:40 pm

In your graph I sww what many users told me: when there is a fault in the DPF system, the soot mass calculated value is wrong and the soot mass measured, that usually doesn't make sense (negative values, etc) becomes the most realiable value to check.
In your graph it seems the ECU forced the regeneration taking in account the measured value, in fact when it reaches about 22 grams, the calculated value, that is very low, is forced to high value to start the regeneration.
This is probably a security function that the ECU uses in case of failure or unexpected data value from some sensor.

Let me know what will happen after the temperature sensor replacing.

Wilts01
Posts: 7
Joined: Mon Mar 02, 2020 10:07 pm

Re: Jump in Calculated Soot Mass

Post by Wilts01 » Sat Jul 04, 2020 5:23 pm

Since my local dealer didn't seem particularly helpful, I went to a local tuning specialist who was recommended. He found that there were some ECU sw updates that hadn't been applied to my Seat Alhambra so he applied them. Sadly this didn't fix anything but I note that VAF DPF is no longer recording values of Post Injection 2 (it says nd) whereas there are values for Post Injection 3 whilst regeneration is take place. This is with a CFFB engine.

On fixing my fault, I am no closer. I have tried using a cheap digital pressure meter to compare with the DPF sensor in the car. At tick over, my DPF sensor reports 20hPa(mllibar) whereas the external pressure meter measures 10hPa. With the car stationary at 2500rpm, the DPF sensor reports 110hPa, my external meter measures 120hPa. So there is a degree of similarity. With the engine off, my DPF sensor reports 10hPa.

If someone has got typical values for the DPF pressure sensor, I would be interested to see them.

Wilts01
Posts: 7
Joined: Mon Mar 02, 2020 10:07 pm

Re: Jump in Calculated Soot Mass

Post by Wilts01 » Sat Jul 04, 2020 9:46 pm

Slight mistake there - I think the lack of Post Injection 2 is finger trouble - I think I disabled it by mistake! Still interested if others have a view about the DPF pressure

Ednet
Posts: 1
Joined: Sat Jul 04, 2020 9:28 pm

Re: Jump in Calculated Soot Mass

Post by Ednet » Sat Jul 04, 2020 9:54 pm

Hello.

Im in a similar situation with a Passat B8 2015 2.0tdi 150hp engine code CRLB and the km is 158e.
The Soot Mass Calc. content does not go up as before to 20-24g. It begins to regenerate around 11 or 12g and the value suddenly jumps up 22g!
Since 1 or 2 weeks ago, it regenerates very often, 100-150 km driven, while before regenerations occured in intervals of 250-400km. My ash volume is at 39.8g from a maximum of 80g, so the DPF i think good.
It is a vagdpf program error or Ecu problem or sensor problem?

Wilts01
Posts: 7
Joined: Mon Mar 02, 2020 10:07 pm

Re: Jump in Calculated Soot Mass

Post by Wilts01 » Sun Jul 05, 2020 3:06 pm

Ednet
What happens to the the Measured Soot Mass value? I presume that is increasing over the period?

The other strangeness with my car is that when the regeneration starts, the measured soot mass value remains permanent at about 25g. If only starts to decrease if I stop driving and then sit with the engine on idle. Once it gets down to 6g (which takes about 5 mins) the regeneration stops. However, the next time I drive off, the whole cycle starts again - ie measured soot mass rapidly (5mins) gets up to 25g and a regeneration is called for.

Post Reply