DPF Cleaning: Which Values Are Adjusted?

The diesel particulate filter in my car is already almost full, with 59g of ash, which is close to the (theoretical) limit of 60g. (Current total mileage is approximately 210,000 km, Passat B6/3C, BMP engine, about 11 years old.)

The differential pressure is normal in all driving situations (I regularly monitor this with VCDS on longer trips), and the regeneration cycle is still occurring regularly (approximately every 350 to 370 kilometers).

However, I have the impression that the regeneration phase (with temperatures around 800 degrees before the exhaust turbocharger and around 650 degrees in the particulate filter) is now taking significantly longer than usual. (Under normal operating conditions, the temperatures are around 400 and 300 degrees, respectively.)

The differential pressure of the particulate filter is around 50 under normal driving conditions, and between 70 and 100 during normal acceleration.

I plan to have the diesel particulate filter removed and cleaned next week by one of the larger commercial providers, as I don't feel confident doing it myself. This will require the vehicle to be at the provider's workshop for two to three days, where they will also make the necessary adjustments to the vehicle's electronics and perform the relevant tests.

In this forum, I did some research (including reading technical articles https://community.dieselschrauber.org/en/viewtopic.php?t=24243),) to find out which values are typically adjusted after PDF cleaning (or will change because the particulate filter becomes 'less restricted').

I wanted to record these values so that I could have a comparison point after receiving the vehicle back.

It makes sense that the value for the ash mass is being adjusted. I also understand that the pressure difference in the particulate filter should decrease.

Which other values might change, and therefore should I keep an eye on?

I would also be grateful for any other tips on what I should pay attention to regarding the order and its execution.

Thank you in advance.

Hi,

Quote:

It is understandable that the value for the ash mass is adjusted. It is also clear to me that the pressure difference in the particulate filter should decrease.

This value is calculated by the engine control unit and must be reset manually. When cleaning or replacing the DPF, this value does not reset automatically.

Quote:

What other values might change, and therefore should I keep an eye on?

Check the values from the differential pressure sensor for plausibility, and ideally, log the differential pressure before and after.
You can find comparison values at:
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

Also, sometimes it's a good idea to check the exhaust gas temperatures in the engine control unit's data logs to see if they are correct.
Perhaps a "normal log" would be helpful for assessment; it might already exist somewhere, but it's not labeled as such.

The coolant temperature must be measured accurately and correctly, otherwise there will be problems with the regeneration process.

There is also a technical article that describes all the factors that can prevent successful DPF regeneration.
/viewtopic.php?t=29120&highlight=dpf+does+not+regenerate

Best regards, Rainer.

Thank you for the quick response and the tips, which I will definitely take into consideration.

I had already learned from the original technical article that the ash mass needs to be reset manually.

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Matching ash mass with VCDS Engine control unit (ECU address 01), then select the VCDS function "Adaptation/Adjustment". Enter the new ash mass value in channel 12, calculation details are in the VCDS label file, see the example in the image below. As a new ash mass value, I entered 4g (DPF is practically new). For newer engine control units, use the function to reset the ash mass.

What I haven't quite understood yet (although it doesn't seem that important, since the ash mass is reset anyway) is the function of "ash learning rate" (presumably only for "fine-tuning" the calculation model in other cases?).

I will probably keep the existing differential pressure sensor for now (this will prevent any comparison from being skewed by data from a different sensor). Currently, a 03G 906 051A (manufactured in July 2018) is installed, which VW replaced as part of a recall campaign (the vehicle is from 2006).

In the meantime, I had installed a newer differential pressure sensor (which was also used for diagnostic purposes at the time), but surprisingly, it failed after only six months. The replacement (part number 076 906 051A) that was sent to me for it has been sitting in the glove compartment for quite some time now.

The old sensor (dated 18/07) shows a differential pressure of zero (0.0) when the ignition is on and the engine is off. At idle, it shows a value between 5 and 7 (when cold or at the end of a journey), and an offset of 10.20 or 12.75 (depending on the day). I occasionally want to install the new sensor, but for the comparison before and after a PDF cleaning, it seems more sensible to leave the old one in place (unless there are arguments for replacing it, which I am not yet aware of).

Sure, you're welcome.

P.S. I had to rewrite the entire message because when I tried to send it the first time, the following message appeared:

Quote:

Access denied! Your IP address has been blocked due to malicious activity in the past.

I'm not aware of any wrongdoing, but I just wanted to say thank you.

Hi,

The message

Quote:

Access denied! Your IP address has been blocked due to malicious activity in the past.

originates from the Spamhaus database. Either you have malware on your system, or your IP address was used for spamming or similar activities before you obtained it.

The solution, however, is also mentioned in the notification.

Best regards, Rainer.