Engine Jerk with DPF: Causes & Solutions

Hello fellow diesel enthusiasts,

ich weiß nicht mehr weiter, bin wirklich schon derbe verzweifelt was mein VW Caddy, mit 1,9tdi BLS Motor, der werksseitig einen DPF besitzt. (0603/AGB). Ich war mittlerweile in 2 VW Werkstätten und jetzt in einer freien Werkstatt. KOne person knows more.

Regarding the history:

The car accelerates weakly within a range of 1700-2300 rpm, which I don't think results in a significant loss of power, but then there's a jolt and the power seems to explode. In first gear, especially when giving it full throttle from idle, the acceleration starts smoothly, but suddenly the front wheels start spinning.

Die Fehlerdiagnose der ersten VW Werkstatt war: Turbolader! So wie der Wagen da war, habe ich ihn vom Vorbesitzer abgenommen und den Turbolader erneuert, der von einer Turbolader-Instandsetzungsfirma General überholt wurde. Also der Turbolader ist der Originale, nur mit neuem Innenleben. Ich habe von dieser Firma bis jetzt 3 Turbos instand setzen lassen und nie ein Problem gehabt. That's all there is to it.
After replacing the turbo, I'm still experiencing the same problem! And on top of that, you can hear the turbocharger. Specifically, there's a loud whistling sound that suddenly disappears when the acceleration jerk is over. The power is definitely there, so maximum speed isn't an issue.

Here's what I did: When replacing the turbocharger, I re-tightened the intake manifold screws to the specified torque. All the screws could be tightened further. Was this already a mistake? I did this because there is a metal gasket underneath. During the removal of the turbocharger, it appeared that a channel had been leaking, as there was some black residue around the exhaust manifold/turbo channel (the turbo and exhaust manifold are one unit in this design!).
After visiting the first workshop, I was told that they had checked the boost pressure and inspected the vacuum hoses. Additionally, the mass airflow sensor (MAF) was defective. Consequently, the MAF sensor was replaced.
Also die erste Werkstatt nicht mehr weiter wusste, ging ich zu einer Anderen: Die meinten das der LLK kaputt sein soll. Ich habe mich da schon sehr gewundert, da ich das Turbosystem mit 0,8Bar selbst schon abgedrückt hatte, was dicht war. Naja dann habe ich eben den LLK ausgebaut und abdrücken lassen. DHe's gone. / He passed away. / He died.
In addition to the above, I removed the EGR valve, cleaned it, replaced the seals, tested its function using a laboratory power supply, and checked the throttle body that sits in front of it. When none of that helped, I disconnected the connector for the EGR valve (the EGR closes when there is no voltage applied). That didn't help either. Also, this valve, which you can only see from below, controls something. Shortly after starting the engine, you can hear its linkage clicking.
I checked the diaphragm by pulling and reattaching the hose while the engine was idling. Everything worked relatively quickly, without sticking or anything like that. I also manually moved the linkage, which worked perfectly fine.
I sealed the exhaust as best I could to try and identify any leaks in the exhaust system. It was only hissing from the clamp connecting the catalytic converter to the muffler. Up front, in the engine area, there was nothing visible, audible, smellable, or felt.
I sprayed the intake manifold with brake cleaner while it was idling.

Okay, so I'm coming from the third workshop. They replaced a vacuum hose that had been patched twice, removed the valve cover and checked the electrical wiring, tried replacing the mass airflow sensor (MAF) with another one for testing purposes, and pressure-tested the charge air system again.

I have also replaced the pressure sensor (turbocharger control) and differential pressure sensor.

So und nun? I'm at my wit's end.
Is there anything else I can try that might help me identify the problem? The fact that this isn't normal is shown by a similar Caddy with 130,000 kilometers on it. Mine now has 170,000 kilometers.

If needed, I can record a video demonstrating the acceleration behavior.

Hi there. Do you have VCDS? If so, use it. First, create a full system scan of the car.
Clear any self-generated errors (signal errors), then restart the process and read the data again.
Then check the measurement values. There should be a label file for your MSG device; this data can be used to evaluate the current status.

"Edit: At 170,000 km, the DPF (Diesel Particulate Filter) might be completely full of ash, and cleaning or, better yet, replacement may be necessary. You can also read out the fill level."

Thank you for your reply.
No, I don't own such a valuable tool. I obtained the license differently.

From your response, I gather that such a log is essential?
If so, is there anything I should be aware of? For example, who could I contact for help in interpreting such information?

I know that my description above sounds quite amateurish, but I tried to describe it as best as I could.
The only tool I have is CarPort, but I don't think it will be useful!


EDIT Are you from Bad Lobenstein? I'm from Tanna. Could we possibly meet up sometime to have errors read out, etc.?

Hello,

It would be useful to have a log that includes the actual air mass, the target boost pressure, and the actual boost pressure.
It is also necessary to check if the turbocharger's wastegate actuator receives sufficient vacuum and that the vacuum system does not have any leaks.
Background: Without sufficient vacuum, the VTG (Variable Turbine Geometry) nozzle on the turbocharger will not fully close, and the turbocharger will only build up pressure very slowly. However, once a certain exhaust gas flow rate is reached, there is enough vacuum, and the performance increases sharply.

Best regards, Rainer.

Meeting.
Sure, no problem. Please send it via private message.

Bitte schreib mir eine PN: Ich kann erst ab dem 5. Contribution...

Let's see what happens next!

and read here:

/viewtopic.php?t=10810&highlight=vintage+setting

and:

/viewtopic.php?t=26673&highlight=vintage+clothing

Then create the corresponding log and post it here. Don't mess with the VTG beforehand.

Bold assumption: The VTG (vehicle tracking system) is malfunctioning or incorrectly configured.

Quote:

From your response, I gather that such a log is essential? If so, is there anything I should be aware of? For example, who could I contact for help in analyzing something like that?

In the medium term, you should consider getting a VCDS device. Diagnostic tests and troubleshooting can already take up a lot of time. It's always tricky when you're using borrowed equipment.

Edit: Oops, I just realized that you're getting really competent help. Then nothing more should go wrong.

"Yes, I'll definitely buy a diagnostic tool. However, I don't want the cheapest one that can only diagnose vehicles with CAN bus systems; I also want to be able to use it on older cars. Right now, my Caddy is really draining my wallet..."

Before I continue writing, I'm waiting for the log, which hopefully will provide some insight at the end.

Do you have the BV39 installed?

At least ours does.
Even though the software in the engine control unit (ECU) might be slightly different, I can help you with comparative data.

AAAAAhhhh but only after the Golf is running again.

Greetings.
Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Yes, that's correct, I have the BV39 installed, as you can see in the picture. Thank you for the offer!

Hello, somehow the car sounds very muffled and booming.

Ash mass balance.
819 RPM Motor speed (G28)
62.0 Ash content
21.6 liters - fuel consumption since regeneration.
240 km distance since regeneration.

VCDS indicates that the DPF is at 60% full, and I agree.
Point 1: The user wants to verschandeln the DPF (Diesel Particulate Filter).
What do you think about the log? I'm initially leaning towards point 1 before opening new projects/workspaces.
In the log, "Stop" or "Continue" was recorded, which is unfortunate because it's not clearly visible. Is it possible to mark this during recording?
We were always accelerating at full throttle.

RedR32 wrote:

In the log, "Stop" or "Continue" was recorded, which is unfortunate because it's not clearly visible. Is it possible to mark this during recording?

Yes, at 100% throttle position.

The DPF should be verschandeln and functioning properly before you start working on the turbocharger... although that would be a setback. In this case (regarding the warranty on the TL), I would start by checking the DPF.

I'm going to start by looking at the DPF now. Somewhere along the way, I was hoping it would be clogged, because that would actually be a simpler repair.

I'm glad I got to meet RedR32 today, and I don't know how to properly thank him. (It was a lot of fun.)
I'm just a little disappointed that none of the three workshops identified the problem.

The particulate filter has now been cleaned. It was rinsed several times with hot water.

The dull rumbling sound was coming from the fact that the sensor exhaust temperature sensor, located below the particulate filter, wasn't screwed into its thread anymore. It was just hanging there...

The whistling was therefore not as loud as RedR32 himself had heard it.

Overall, that jolt is still there! However, the cleaned particulate filter hasn't been registered in the software yet. But I don't think that should have any impact, right?

That exhaust temperature sensor thing is making me suspicious. Shouldn't the software have detected that?

Hello,

Martininii wrote:

The thing about the exhaust temperature sensor makes me suspicious. Shouldn't the software have noticed that?

Yes. Is the software up to date? What version of the software are you currently using?

Quote:

Flushed several times with hot water.

Exactly how? You don't need to start with a watering can for this; I recommend using a 3/4" hose with sufficient flow rate.

When cleaning the DPF, the success of the process should be determined by measuring the differential pressure (before and after), and the ash mass should be adjusted accordingly.
Immediately before dismantling and cleaning, the DPF must be forced to regenerate because otherwise oil residues and soot will prevent the ash from being flushed out.

Best regards, Rainer.