Fehlersuche bei Golf 6 TDI 66kW (5K1) | Posts 48+

I will be logging a drive later this afternoon, recording acceleration and load.

The calculated soot level is also within a normal range, and it would then reach approximately 600-700 km before increasing to 21 grams, triggering a regeneration process.

The problem is the "measured soot level," which increases very quickly. In 20 kilometers, it goes from 2 grams to 21 grams. And when it reaches 21 grams, it also includes this value in the calculated soot level and starts the regeneration process. During regeneration while driving, the calculated soot level quickly decreases, but the measured soot level never falls below 18 grams. It's only when I stop the car and allow the regeneration process to continue while it's stationary that the measured soot level drops to as low as 8 grams, and then the regeneration process completes.

Therefore, it would be interesting to know how the MSG calculates the "soot level" measurement.

Hi,
The "soot level" is calculated based on the pressure difference across the particulate filter (differential pressure sensor) and the gas flow rate. The latter is calculated based on air mass (air mass sensor), fuel injection quantity, and temperatures (temperature sensors) before and after the particulate filter.
hg
Herbert.

This log file contains some acceleration tests, both without regeneration and during regeneration. It can be recognized by observing how the amount of soot moves up or down.

Unfortunately, I don't have a KDataScope yet, but I've ordered one and am waiting for it to be delivered.

I see two strange things:
1) The turbocharger pressure and air mass suddenly spike. I don't know that.
2) The pressure difference exceeds 400 mbar in many areas. It seems the DPF is clogged.

The high differential pressure remains even after regeneration. Therefore, I would say: either the DPF is full of ash, or a false differential pressure is being measured. You have stated that you have ruled out the latter. Therefore, unfortunately, all that remains for me is the DPF (Diesel Particulate Filter).

However, I'm still wondering: Why is there so much more ash present than what MSG believes it should be? Even if the injector was faulty back then and produced a lot of soot, the system should have regenerated frequently due to the soot and differential pressure, and the ash mass should have been accounted for accordingly. However, it doesn't seem to have happened to the extent that it did in reality.

Maybe someone else has a tip for you.

Hi,

Quote:

Why is there so much more ash in it than MSG believes there should be?

"Adaptation" during the described engine control unit (ECU) exchange?
hg
Herbert.

I conducted several tests at an engine speed of approximately 1500-4200 RPM, using the 4th and 5th gears. I fully depressed the accelerator pedal at 1500 RPM and put the car under load. Not every attempt was successful, as the highway wasn't always clear, and it was necessary to have a good view to see if there was a radar anywhere.

During the MSG exchange, an ash content of approximately 40g was used. However, the ash content, as well as the soot values, are actually only "calculated" values. Could it be that a malfunction in the fuel injectors caused a large amount of unburned fuel to pass through to the DPF, clogging it?

After the regeneration process, the differential pressure dropped back to approximately 20 mbar. From other tests, I know that it gradually decreases further. When I turn off the engine and restart it, the pressure is around 10-12 mbar. The differential pressure is 0 mbar when only the ignition is turned on - I have already tested this.

Does it make sense to increase the ash content, for example, to 65-70g for a test, and check if the behavior changes?

Hi,
I have a sneaking suspicion that you might have caused problems with your car's engine control unit (ECU) by having it replaced with a tuner's unit, and that this is now affecting your DPF (Diesel Particulate Filter). Why? When tuning, maps are modified, and reverting to the original software in a VW vehicle does not change these modified maps.
Just as an aside, I've also noticed that the spray pattern of the old injectors wasn't checked (which would be unprofessional).
Don't rely too heavily on certified experts.
hg
Herbert.

Thank you, Herbert.

I'm going to chat with the tuner tomorrow. He told me back then that the software settings and calibration maps were set to the original specifications, because I didn't want any tuning parameters.

Okay, bitte gib mir den deutschen Text, den du übersetzt haben möchtest. Ich werde dir dann nur die englische Übersetzung geben.

Hi Herbert, I just stopped by the tuning shop – it's just around the corner. He removed the MSTG and connected it to his testing equipment. There are no tuning parameters present. Everything is as it should be.

Hi,
I'm at the end of my rope with this, and I'm out of ideas.
If a particulate filter has accumulated 200,000 kilometers, it would be reasonable to recommend replacing it. However, this leaves only the suspicion, with a few unanswered questions due to the background.
You yourself say that otherwise everything is fine. Does this also apply to the exhaust path after the particulate filter? We used to have a crumbling SCR catalytic converter here, but as far as I know, CAYC doesn't have that model yet.
If you're dealing with a diesel particulate filter (DPF), don't even bother trying to verschandeln it or use a refurbished canister. If you use an original part, you'll at least be on the (relatively) safe side.
hg
Herbert.

Hello Herbert.

Today, I did a test. I set the ash mass to 65g (the maximum is 70). Then, I drove it. The car managed to travel 20km further before it went into regeneration mode. But, as I said, this is just a "trick" of the MSTG (presumably a system or device). The old MSTG (before the exchange) had lost 30 grams in ash mass.

My guess is that the catalytic converter (KAT) is quite clogged. That's why the direct injection system (DDS) isn't working properly. It was probably caused by poor combustion (a lot of unburned fuel reached the catalytic converter).

To the best of my knowledge, the catalytic converter/diesel particulate filter (CAT/DPF) is structured as follows on the CAYB.

Oxygen sensor -> Catalytic converter -> Pressure and temperature sensors before DPF -> DPF -> Pressure and temperature sensors after DPF.

I'm going to use the endoscope tomorrow. I'll insert it through the lambda sensor so I can see the catalytic converter from above, and then through the temperature sensor so I can see the catalytic converter from below and the DPF from above. It's not possible to access the DPF from below, as I would likely need to remove it for that.

Hi,

"If the DPF is clogged, it doesn't matter where the ash/soot is located. However, it is 100% certain that it is in the channels. The DDS sensor measures the pressure in the expansion chamber *before* the filter element, which is located in the cylindrical (or oval, depending on the vehicle) section. Even if there were mountains of ash there, the DDS would still measure the pressure in that space." Unless the wiring between the DPF housing and the sensor is faulty.

At least, the DPF (as far as I can tell) doesn't look broken.

Image 1 - Top view of the catalytic converter, showing the oxygen sensor inlet. Unfortunately, it's blurry because the distance is too small there.
2. Image - Underside of the KAT (Klimaanlage/Air Conditioning) unit, showing the entrance to the temperature sensor.
3. Image - Top view of the DPF above the inlet temperature sensor.

Good evening, are you 100% sure that the intercooler system is airtight? Have you checked it for leaks? If the soot mass, as you said, increases during regeneration, even while driving, that strongly suggests too much fuel and not enough air. Is the EGR valve really okay? The parts have caused a long and numerous amount of problems.
I can't imagine that the DPF is clogged, otherwise it would show a higher mbar reading even when the car is stationary.
What does the altitude pressure sensor indicate? He is integrated into the M-stage, and if the values are incorrect, he could affect the entire M-stage calculations.

Best regards, Dago.

I don't have any devices for creating pressure. But I'll go get the kids' fog machine from the basement and flood the system. Maybe I'll see something then. I will also use this to check the hoses of the differential pressure sensor.

Hello Dagomanu.

Today, I tested it with a steam engine. After the initial measurement, I blew in a good amount of steam. I used a disposable glove to seal it. The glove inflated quite a bit and also held the pressure. No steam escaped from anywhere in the engine compartment.


They also used an endoscope to look inside. The inside appears to be slightly oily, likely coming from the crankshaft ventilation system. I've attached some pictures.