TDI regenerates too often!? Where does all the soot come from? (Solution)

Hi, hello,
I'm basically just along for the ride here, and I've already thoroughly searched the entire forum, but I'm still unable to find a solution to my problem.
Problematic Vehicle: Sharan 7N 2.0 TDI, CR-Diesel with SCR Cat, 103 kW, Engine Code: CFFB
Diesel scandal engine EA189 with software update since approximately 70,000 km. Mileage: 197 TKm
My Problem:
For the past three weeks, the fans have been running for approximately three minutes after the engine is turned off, even after short trips. The water temperature sensors provide logical values, and the fans should not be running after the engine is turned off; the water temperature is not in the critical range. Start-Stop is not available when the water temperature in the KI reaches 90 degrees.
Two weeks ago, during a full scan, I found the following error:
15733 – SCR NOx Catalyst Bank 1
P20EE 00 (096)- Efficiency too low
Sporadically-unverified-checked since last deletion
The inspection of the lines and connections did not reveal any abnormalities. The error was deleted and has not reappeared since.
The fan is still running continuously, and the start-stop function remains unavailable when the engine is warm.
I must also mention that my wife drives the car, and I don't always have access to it. On weekends, I have been taking care of the patient myself.
When the fan is running at full speed, very hot air flows under the car. For me, this is a sign that the regeneration may have been interrupted. I was unable to determine how many times the regeneration had already been interrupted using VCDS, as I found a 0 in the corresponding section.
I replaced the pressure sensor last week as a precaution, it couldn't hurt, the line to the DPF is clean.
It's now amazing that the car apparently regenerates daily, and that's with a daily commute of 2 x 40 kilometers, both on highways and country roads. So far, my wife has never noticed any signs of regeneration, and neither have I, everything seems normal.
Yesterday evening, after a 60-kilometer drive on a federal highway at approximately 120 km/h, the DPF light came on. Upon arrival, I let the car run while stationary until the engine speed dropped from almost 1000 rpm to a normal speed. The fan was running a little rough, but the DPF light was on.
On the way back, after about 40 kilometers, the DPF light came on again, but I stopped the car, as it was already late.
Today, I drove the car for about 50 kilometers and recorded the relevant values. I have attached the file. It regenerated efficiently, and the DPF light remained off. I'm only concerned about the rapid increase in soot mass at the beginning, that's why I also included the exhaust gas recirculation.
I'm strangely not experiencing any increase in oil levels!
I would like to comment on this file here, but I don't want to continue commenting on it. Maybe someone of you has a solution, I'm currently just going around in circles.

Thank you in advance!
Greetings
Ralf

Hi,

Thank you! Unfortunately, the "Log" setting uses "g/s" (grams per stroke) instead of "mg/stroke", which makes it difficult to compare with experienced values.

You can also check yourself to see if the target range for air mass is approximately equal to the actual value, and whether the actual value does not reach astronomical values (= a gap, air is leaking out) at full throttle.

Anything that causes excessive production of Russ (exhaust gases) is relevant, especially if it results in insufficient combustion air in the cylinders or defects such as leaks caused by a faulty turbine bearing on the turbocharger.

The most likely cause is probably damage from a marten biting into the air intake hose or cracks in the air intake hose or the air intake system. Reveal yourself through oil stains.

Best regards, Rainer

Thank you, Rainer!

I took another test drive today in order to see exactly if there was a leak. I have attached the log file. The air mass is specified in mg/stroke!
I'll take a look at it myself again, but four eyes see more than two.
Are the values from the differential pressure sensor plausible? Everything I've found in this forum indicates that the values are generally lower when the system is idle. Since I need to work with extended measurement values, I can't find any target values for the differential pressure there.
I'm right, aren't I, that the soot mass is increasing too quickly, even during the field regeneration?
I'm sorry that I can't answer seemingly simple questions myself, but the whole exhaust gas cleaning technology didn't exist during my school years! I have to familiarize myself with the situation first before I can deal with such a problem!

Greetings
Ralf

I think I've found it!
At 3200 RPM, the target air mass flow rate is 1029.70 mg/cycle, but the actual value is 422.10 mg/cycle!

The turbocharger is fighting against this, but should have 1.089 bar, but instead shows 2.201 bar. Weird that I'm not getting any error messages!

I have attached an image of the disaster!

That means for me, I should take a look at my car tomorrow, check the hoses, etc.!

If I'm wrong, I'll stop!

Greetings
Ralf

Hi,
can you please extract the information from the MSG and post it here:
- Particulate filter: Time since last regeneration
- Particulate filter: Oil volume
- Particulate filter: Soot mass calculated
- Particulate filter: Soot mass measured
- Particulate filter: Miles since last regeneration
- Particulate filter: Fuel consumption since last regeneration
- Field regeneration loading limit
- Service regeneration loading limit
- Load Limit Exceed
- Vehicle distance
- Particulate filter: Oil mass
This provides an overview of the condition of the filter. You can save these values as an (u01 file) selection and access them whenever you need.
hg
Herbert

Of course!
Just finished it!
Motor is included.
I have attached the protocol!

Greetings
Ralf

Hi,
Immediately after regeneration, the "measured" soot value is already back at or at its maximum.
What are the values of the differential pressure sensor when the engine is stationary?
I am aware of the case where the calculated soot mass is significantly higher than the measured value. This can lead to frequent regeneration, and this process ends when the smaller value approaches zero, without the corresponding higher (calculated) value also being correspondingly low.
If possible, could you please record a regeneration using the data above? There is also a status bit for the regeneration status.
hg
Herbert

The pressure difference sensor showed 17 after a long period of inactivity, while after the last log flight, it showed 45 when the warm engine was stopped.

I will check the hoses from the turbocharger to the intake manifold this evening. It seems that the air mass significantly drops below the target value at higher speeds, which I suspect is due to a leak in the intake air system. This leads to increased soot formation...which prevents the field regeneration from keeping up.
I will know more tonight.

I will report.

Hello
Ralf

Just from the garage, here's my report:

The intake manifold is tight, I've checked the entire area and managed to achieve a good 1.5 bar of pressure throughout, with no pressure loss or hissing sounds.

I'm now just as smart as I was before...

Even though I am now very insistent, I would be very grateful for more tips.

Could it be that the new, original Bosch differential pressure sensor is providing incorrect values, and thus repeatedly triggering the field regeneration? The values he provides seem simply too high, or do you find them plausible?

Greetings
Ralf

"Too high" is still a rather understated description. When the engine is idling, the value should be close to 0 hPa. See /viewtopic.php?t=27732
Where was it purchased? (Not what).
hg
Herbert

So, der Differenzdruck am DPF, wenn der Motor ausgeschaltet ist und der Zündkerzenstecker angeschlossen ist, sollte etwa 0 mbar betragen.

The sensor was purchased from a friend, but I will also get a new one...
Practice makes perfect!

Hello
Ralf

Choose the sensor based on the FIN/parts catalog, not the pattern.
What is the car's history (previous owner, mileage at the time of purchase, any notable issues)?
hg
Herbert

He also did that at the beginning!

I bought the car three years ago with 126,000 km on the odometer. It was a company car for an employee. Now it has 197,000 km on the odometer. Mileage: 30,000 km per year, with very few trips under 40 km on country or main roads.

Maintenance up to 126,000 km at authorized service center, thereafter by myself!

No special incidents in the last 70,000 km!

Hello
Ralf

Hi,
It's just speculation, but if a particulate filter is full (ash loading), then
- if the differential pressure (becomes) too high,
- regenerates the DPF very frequently,
- The exhaust gas flow is reduced due to backpressure, and consequently, the boost pressure and air mass (this is noticeable at high target values).
The ash loading value is a variable calculated value.
hg
Herbert

I will continue my research over the weekend...
Please provide the text you would like me to translate. I will ensure that all placeholders are preserved exactly as they are.

Best regards, Ralf