Jump in Calculated Soot Mass

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

Re: Jump in Calculated Soot Mass

Post by andreim90 » Mon Jul 06, 2020 4:36 pm

@wilts01

For diff presure values,see my posted graph on this topic. The diff presure is the blue line,and the coresponding scale in on left side of the graph(at hundreds).

The fact that soot measured only decreases when idle during regen is even more odd than our behaviour.

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

Re: Jump in Calculated Soot Mass

Post by Humbucker » Mon Jul 06, 2020 9:45 pm

Hello,
Update. I have searched the internet and found quite a few people have the same problem after a cam belt change, might be coinsidental.
Bought and registered the VCDS and did a full scan.
I was told to check the two pipes for splits that go to the sensors but all seemed ok, I blew down both pipes and both seemed similar.
Took off the sensors and blew into both pipes, checked the resistance on pins 1-2 1-3 2-3 and all seemed comparable.
Since then the soot mass has not jumped and now goes up to 100% before re gen.
Will monitor for a few weeks.

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

Re: Jump in Calculated Soot Mass

Post by andreim90 » Wed Jul 08, 2020 8:35 am

Humbucker wrote:
Mon Jul 06, 2020 9:45 pm
Hello,

Bought and registered the VCDS and did a full scan.
I was told to check the two pipes for splits that go to the sensors but all seemed ok, I blew down both pipes and both seemed similar.
Took off the sensors and blew into both pipes, checked the resistance on pins 1-2 1-3 2-3 and all seemed comparable.
Since then the soot mass has not jumped and now goes up to 100% before re gen.
Will monitor for a few weeks.
Hello Humbucker,

Please can you try to re-explain the quoted paragraph? Im not a native english speaker and maybe thats why i understood so little. Im very interrsted in the subject but i found it hard to understand, for example i dont understand who told you to check the two pipes, what are the two pipes, what kind of sensors you are refering to(temp or pres), how many regen cycles you ran since this "intervention" without soot mass calc jumping?
Are you also monitoring soot mass measured before /after? Something changed?

Thank you

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

Re: Jump in Calculated Soot Mass

Post by Humbucker » Thu Jul 23, 2020 3:40 pm

The two pipes I talked about are the ones going to the pressure differential sensors. On my B8 2.0L Passat they sit under the engine cover in some heat resistant silver cover material. Its done two full cycles now ok but I am on a 500 mile round trip this weekend so will se how it goes then.
I was told to check the pipes from the owner of the VCDs forum before spending money on sensors as I supplied a full scan of the car for him to diagnose the faults on the pressure diff sensors.
I run the app every trip so I know if it jumps and at the moment its fine.

PsilosTdi
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Joined: Tue Aug 25, 2020 4:14 pm

Re: Jump in Calculated Soot Mass

Post by PsilosTdi » Tue Aug 25, 2020 4:35 pm

Hi
I have a VW TOURAN 1,6 TDi with a CRKB engine .
Done 33000klms the exhaust and Regen where fine .
I use only Shell V-power fuel ,but last filling I did after 40 klms the engine light came on ,did a scan with a obd scanner and found P2002 and PO4040 codes ,first is with dpf and second is for egr low flow ,the car smokes from the exhaust on idle and when I press hard on the pedal,
The vagdpf app shows 45% dpf full then it jumps to 100% and starts to Regen ,when it hits 25% it stops ,now does Regen every 40-60 klms ,before it did every 220klms .
At the service they told me it was probably bad quality Diesel.
And wait to burn it all ,and refill with some dpf cleaner and would probably solve the problem 🤯
I think I have already dmg my dpf ,and I'm trying to see if some sensor is faulty and the Diesel filling was just a fluke.
What do you guys think I should do?

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admin
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Re: Jump in Calculated Soot Mass

Post by admin » Tue Aug 25, 2020 6:24 pm

Usually these jumps from a medium/low soot mass value to 100% happen when the ECU diagnostic see something working wrong, a sensor with inplausible values or faulty.
It's the first time I read this kind of explanation related to the diesel quality, but I don't exclude it can be true. You'll have the first confirmation when the fuel tank will be almost empty. I think the ECU will be highly conservative to avoid any risk of fire in the DPF, so probably it will remain in this "emergency" state also after a new fuel refilling, in this case wait a few hundred km more.

Keep us informed about the results.

wintermute
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Joined: Fri Aug 28, 2020 9:30 am

Re: Jump in Calculated Soot Mass

Post by wintermute » Fri Aug 28, 2020 9:34 am

Hi
I have a similar problem with my 2014 VW Sharan 2.0 D.

It is more or less always in degeneration stage. I can run the car for 1-2 minutes before the EGR valve closes and there is a sudden spike in calc soot mass value. It will not stop degenerating regardless of how far I drive.

Added a screenshot from the app
Attachments
152159_VAG DPF.jpg

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admin
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Re: Jump in Calculated Soot Mass

Post by admin » Fri Aug 28, 2020 4:28 pm

Have you checked the error log in the ECU?

PsilosTdi
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Joined: Tue Aug 25, 2020 4:14 pm

Re: Jump in Calculated Soot Mass

Post by PsilosTdi » Fri Aug 28, 2020 9:15 pm

Update
I burned the tank with the "bad Diesel"
Fill up and put a dpf protect from Liqui moly.
Now I have reached 60% and still no Regen yet ,I have 300+klms from last Regen.
But the engine light is on again ,and the car is smoking in idle and in hard acceleration.
Looks like I have a bad sensor or something.
Can some one plz tell me what is this I have labeled on the pic I posted .
High press egr closing % what is this ?
Attachments
IMG_20200828_220243.jpg

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admin
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Re: Jump in Calculated Soot Mass

Post by admin » Sat Aug 29, 2020 9:14 am

EGR = exhaust gas recirculation
It's the valve that control the gas recirculation from the exhaust manifold to the intake manifold. This recirculation may seem strange, but it's necessary to reduce the temperature inside the combustion chamber and consequently to reduce nocive emissions. Obviously this gas injection inside the intake manyfold reduce also the performance and this is the reason why the EGR valve can be controlled changing its opening percentage. When you're driving slowly at constant speed, the EGR can recycle an high quantity of gas, in the contrary when you ask the maximum performance the EGR stops the gas recirculation.
https://en.wikipedia.org/wiki/Exhaust_gas_recirculation

In the modern diesel engines are present 2 EGR: high pressure and low pressure. The difference is the position where the exhaust gas are picked up: high pressure is before the DPF and low pressure is after the DPF. 2 EGR valves permit to reduce the emissions better than a single EGR.

During regenerations process, the EGR is closed or almost closed to help the combustion chamber increasing temperature.

If your problem is related to the fuel quality, as it seems, I suggest to wait another 1 or 2 refueling to let the ECU learn the new fuel quality. I don't think the ECU can change its parameters in real-time depending on the fuel quality.

Tyrezog
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Joined: Thu Aug 27, 2020 9:23 am

Jump in Calculated Soot Mass

Post by Tyrezog » Sat Aug 29, 2020 12:22 pm

I still didn find a good answer. Im sure that the calculated value is used by the ECU to manage the regeneration process, nut the measured value is stil mysterious for me: for example it can go down to negative values that are meaningless for me. Some users told me that in case of failure of some sensor, the measured value is the only one useful to understand the condition of the DPF system. In my experience I didnt tested that kind of situation, but trusting those users, I added the measured soot mass value to the app.

PsilosTdi
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Joined: Tue Aug 25, 2020 4:14 pm

Re: Jump in Calculated Soot Mass

Post by PsilosTdi » Sat Aug 29, 2020 4:28 pm

Thank you very much for the answers and the link .
I have a appointment at the dealership to check the car .
I'll update.
I had a jump now from 69% to 100% and the car started a Regen cycle ,after 300 klms trip back home I'm at 45% now .
I will update when I have news from the dealership.

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