Ash Content: What is it and why it matters?

Hi.

I just went for another DPF regeneration cycle.
Since the update to version 1184, the noise has disappeared, but you can still tell when it's about to fail because it starts sticking to the gas line and behaving erratically.

Inzwischen hat sich der Aschelernwert geaendert. -1.4%
What does that actually mean?


I now have 5.08 grams of ash after 19,000 kilometers.

Code:

068,0,Partikelfilter (Abgaswerte II) ; Nur während der Regeneration gültig! ; Umgebungsbedingungen: 50-60 km/h / 3. Gang / Drehzahl <= 3000 U/min 068,1,Beladungs-,koeffizient,Sollwert: max. 40.0 %\n\nAb 40.0 % beginnt die Regeneration im Fahrbetrieb. 068,2,Aschemasse,,Sollwert: max. 150.0 g 068,3,Aschelernwert ;

The only thing Google pulls up are my own contributions here .

Does anyone know anything?

m;

Hi Martin,

With the BRE motor, you notice very little during regeneration.

Quote:

Inzwischen hat sich der Aschelernwert geaendert. -1.4% What does that actually mean?

[Speculation begins]
The engine control unit monitors the differential pressure and adjusts its estimates of the ash mass accordingly, because you are, for example, using fuel/engine oil with low ash content (metal salt additives)?
[Speculation from]

Best regards, Rainer.

Correction factor for the model-calculated ash mass.

dieseltester wrote:

Correction factor for the model-calculated ash mass

Okay, I will provide a more detailed and understandable explanation. Please provide the text you would like me to translate from German to English.

During regeneration, the DPF burns off the soot, which then turns into ash that cannot be burned away. The ash load value is calculated based on factors such as the filling level, the number of regeneration cycles, and the differential pressure. To calculate the ash load value, the system needs the ash learning value, which also needs to be reset to zero when a DPF is replaced.

I hope I haven't written anything incorrect here.


Marco.

Marco.

That can't be right, because it seems to be calculating the learning value itself.

I now explain it to myself like this:

A "normal" BMR (presumably referring to a type of engine or vehicle) consumes 7 liters per 100 km, which means it produces x grams of ash per 100 km.

The MSTG anticipates this and is now organizing various events.

Since I tend to drive more economically than "typical" drivers, I consume slightly less fuel, which results in slightly less ash production. Therefore, certain maintenance procedures might not be necessary as frequently.

By the way, the learning rate is constantly decreasing; it's already at -2.x%.

m;

Okay, I just found something about how the ash content is calculated:

Ash content = (Mileage (km) * Average fuel consumption (liters) / 100) * Ash coefficient (0.0046 g / liter)

Hm

This specific formula is a model - the ash mass is present as a solid in my DPF, but it cannot be weighed.

In your calculation, the term "ashvalue" does not appear anywhere.

He can't, because the formula is a static model.
They can only be applied if you know all the inputs.

The word part "Lernwert" suggests that something is learned during the operation of the vehicle, which was not fixed at the time of development because it depends on personal factors.

Modern automatic transmissions learn their driver and adapt to them by adjusting the programmed shift points.

The only thing that changes when learning to estimate ash content is the individual variation compared to the model established during the development process.


m;

...or the reason for the changed data status?

Okay, please provide the text you would like me to translate from German to English.

a new reason to question the meaning of the ash content value:
It's consistently decreasing for me, and it was at -5.3% most recently.

Today I received an update from 1881 to 4369...
and the value is back to 0.0%.

What is the purpose of this value, and what happens if it is set to zero ?

m;

While I'm not entirely sure what the intended learning value is supposed to be, it has reached -10.4% after 99,000 km. However, the MSG (presumably a software or system) has received several updates during that time (0061 -> 0424 -> 1185 -> 2968; after that, the warranty expired, and it wasn't enough to reach version 46xx).

Since 26g of ash mass has already been recorded, I would be happy to receive any negative corrections ...

Regards,
Peter.

I'm speculating that the MSG (presumably a measurement and control system) measures the differential pressure immediately after the regeneration process.

It is certainly the differential pressure of a new, ash-free DPF that is defined, as well as the differential pressure of an ash-clogged DPF.

Furthermore, there is a calculation model for the amount of ash produced.

Based on the differential pressure, the ash mass value can now be corrected along the entire length.

I can't imagine that the consumption would be included in the learning value, since it is already present in the calculation model.

Unfortunately, my Passat doesn't have that feature yet, which is a shame. It still uses conventional oils, so the DPF doesn't need to be replaced (or cleaned) as often. Of course, the additive likely contributes the majority of the ash content.

HI.

Yes, it must have something to do with "computational models."

The BMR-6SG variant is supposed to have a fuel consumption of 6.4 l/100km, but I'm getting 6.8 l/100km (average since purchase), but the learning value was *always* negative. And it became increasingly negative over time (monotonically decreasing).

If Bennis' approach is correct, the old (-5%) value should reappear at the latest after the next regeneration cycle. I'm driving over 100 km today, and I'll check again then.

My engine has the following history: 0420 -> 1184 -> 1881 -> 4369.
0420 Release date: February 2007 - by then, the 1184 was already available on the market.
On August 7, 1184, there was an issue because the engine was making a lot of noise during regeneration. After the update, the DPF light came on after about 30 kilometers, which, in my opinion, was also a consequence of the update and a strangely reset counter. I followed the "high-speed driving" procedure as described in the manual, and it was okay.
In 1981, during a field campaign involving differential pressure sensors, he was in the workshop due to a faulty horn. This is the venting software.
"In 4369, it became undrivable at 2000 rpm because it started shaking. And 2000 rpm is a common speed on the highway that I often drive on. Perhaps the other versions would have also shaken, but I had a different driving profile before."

m;

Supporting Bennis' theory, the learning value has decreased from a regeneration rate of 0.00% to the expected -5.00%.

m;

Thank you for the feedback.

So, it seems that the learning value is important for the regular regenerations, which are then triggered by the corresponding pressure differences. Ultimately, in this case, your DPF can absorb 5% more soot before it needs to be regenerated.