Soot Mass Measured not visible

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o.b.
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Joined: Thu Aug 25, 2022 12:25 pm

Soot Mass Measured not visible

Post by o.b. » Thu Aug 25, 2022 12:54 pm

Hello and greetings from Finland,

I have 2016 Passat with CRLB without SCR. I would be interested to see Soot Mass Measured. Now there is Nox sulfur charge visible on the screen and I am not that interested on that. I think Nox sulfur charge is more important in engines with SCR? Please correct me if I am wrong.

I am trying to figure out what triggers regeneration when Soot Mass is not yet 100% (usually around 90% when regen starts). Perhaps it is measured value which I don't see that triggers it.

I know same engine model was produced later on with SCR system.

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admin
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Re: Soot Mass Measured not visible

Post by admin » Fri Aug 26, 2022 10:11 am

Usually the soot mass measured gives useless (for us) values because totally unrelated to the normal soot growth and often negative (confirmed using the official VAG tool).
This is the reason why in the first releases of the app I skipped that value, but then many users asked me to introduce it because it seems that when there is a sensor failure in the DPF system, the soot mass calculated values become wrong and the measured values become correct. It's strange, but it's confirmed by many users. So, for engines directly tested by me, of which I have the complete parameters log, I added the soot mass measured, but for engines tested by users I don't have a confirmed value to be used and I prefer to keep the confirmed Nox accumulation value.

Anyway, you can try another engine group looking for a readable soot mass measured value. If you find it you can have an idea of the usefulness of that value, but as I written before, you'll probably agree with me that it's useless.

o.b.
Posts: 2
Joined: Thu Aug 25, 2022 12:25 pm

Re: Soot Mass Measured not visible

Post by o.b. » Fri Aug 26, 2022 9:12 pm

Thanks for reply admin.

I'll check with VCDS if I can find Soot Mass Measured and if values make sense or not.

If that value could somehow indicate that there is problem with some sensor it would be very valuable info to many of us.

Would it be possible to have toggle switch to Nox sulfur charge square? i.e. Nox sulfur charge (by default) -> (1st press) Soot Mass Measured -> (2nd press) Off

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admin
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Re: Soot Mass Measured not visible

Post by admin » Fri Aug 26, 2022 11:18 pm

I don't have a detailed database of each engine. Many of those present in the list have been tested by users with an existing setup for another engine, if they've found all parameters read correctly, the I added the new engine to the engine group.
To find the correct "soot mass measured" for your engine, you should change the engine group in the options menu and check if some of them let your read the parameter correctly. If you find it, let me know the engine group used. It could be possible that you find a group in which all parameters, included the soot mass measured, work correctly for your engine. Many groups differ only for 1 or 2 fields.

A failure in some sensor (usually the differential pressure one), can be easily noted when you see the soot mass calculated value increasing very slowly and suddenly it jumps to the field regeneration limit (for a 2.0 TDI is near 24 grams). This is the common behavior of a malfunction, the soot mass measured values are random and in some way crazy, I don't think they can be used to have a reliable feedback about the system.

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