Sporadically high loading pressure?

This error message shows the control unit from my neighbor's 100PS car. I don't know the engine code, but it probably doesn't matter here either.

The problem manifests as follows: Suddenly, on the highway, there is no more performance, the device seems to be going into emergency mode. No power, only about 120 km/h is possible. The annoying thing about this is that it only occurs sporadically. Maybe once every 1000 km. How can I find out which component is to blame? I can't really ride along and hope that the error occurs at some point so that I can then read the values at that moment. Are there perhaps standard parts that are known for intermittent failures?

There are several possible components that are so well-known that a whole library of technical articles has been written about them. Reading the same and the built-in search function are incredibly helpful.
If you find this too complicated, you should take the vehicle to the workshop.

I was expecting an answer like that

I am aware that this type of question has probably been asked before, and that people who have been here for a long time are quite annoyed by such questions. However, after reading posts here for about 2 hours and not really getting any useful information because there are so many posts that all seem to be slightly different, I lost my motivation. Think about it this way: How many hours have you spent reading and writing here? You know all of this because you have been here for a very, very long time, and it has all developed gradually. And in all of this information, am I supposed to find what I'm looking for? I tried. But I don't have that much time anyway, especially since it's not even about my own car.

That's why I thought I could ask the question in the area where everyone can write. If people who are very active here feel annoyed by something, then they probably don't want to answer, right? That's why the "two-tiered system" was introduced here, even though it shouldn't exist (yes, I've read it!).

I am familiar with this issue from a much larger forum. Interestingly, this was effectively solved by a wiki system where all articles describing fundamental, frequently requested information were consolidated. This provided us with a significant advantage because it was often difficult to keep track of everything in such a forum. Essentially, wiki.dieselschrauber.de

The issue with the garage was, of course, also our idea. But, as experience has shown, exactly what we have often encountered (and as is also described in a basic article here): The garages simply replace all parts that might be related, under suspicion, because they are unable to understand the entire "modern diesel engine" system and cannot carry out a conclusive diagnosis, which, in my opinion, is exactly what their job should be. In the same vehicle, a lot of parts were replaced at once because it had stalled in a cold state. While the error is gone, the bill was very high, and it was probably just one component out of all the parts that were replaced, and maybe even a cheap one that should have been found by a reputable repair shop.

Upon the request of the workshop, they stated that they could only replace it based on suspicion. Which I can actually understand in this case because the error only occurs sporadically. Once the engine is turned off and restarted, the error should be gone.

Daher war meine Frage nicht nach einem vollständigen Lösungsweg, wie man den Fehler finden kann, sondern ob es bestimmte Erfahrungen gibt, so dass man sagen könnte: Meist ein loser Stecker an diesem oder jenem Sensor, oder ein defekter Sensor oder Magnetventil oder irgendetwas in dieser Art. I currently don't have the time to conduct a more thorough investigation.

I would like to inform you that I have not found anything.

Outsider wrote:

If there are specific experiences, such as saying that it's usually a loose connection on this or that sensor, or a faulty sensor or solenoid valve, or something like that.

Hi,

For occasional LD (Load Limit) exceedances, there don't seem to be any "standard" causes, as far as I know.

I would like to participate in the VTG mechanism, including. Start searching for a membrane.

Outsider wrote:

I can't tolerate riding along and hoping that the error will eventually occur so that I can read the values at that moment.

That sounds like you have a diagnostic system. Just do a diagnostic run. It's possible that the boost pressure is always significantly and for a long time above the target value, but the conditions to enter the limp mode are only occasionally met. This at least allows you to see if a part replacement was successful, without having to wait for the next really worn-out component to fail.

Bye
pax

Hi,
This seems similar to the performance loss problem I had, which I was able to solve after extensive reading in this forum, with help from this forum, and some frustration in the workshop. In my case, the simple problem was that the magnetic valve for limiting the boost pressure was defective, which no longer sent overpressure to the membrane housing of the wastegate, which is why it no longer opened, resulting in high boost pressure during aggressive acceleration. I was able to observe this after I had installed a boost pressure gauge. As soon as the excessively high boost pressure lasted for about ten seconds, the control unit would regulate it. The magnetic valve was electrically fine, but it no longer clicked when in operation. Exchanged, everything is fine.

That certainly doesn't have to be the case in your situation. As pax already recommended, perhaps a confession might give you some insight, or you could build an LDA and then proceed systematically. Since the error can have many causes, it is already sensible to perform a systematic troubleshooting process based on the technical article and then ask here for further clarification.

Good luck
Florian

hi Outsider

The engine codes would also be helpful.

Quote:

This error message indicates the control unit from the 100PS model

After that, I'm going to use a VTG loader. And at such high loading pressures, there isn't much left to do.

1. Leitschaufel mechanism jammed
2. Membramedose stuck
3. Tax valve is jammed
4 too short vtg bar

Best practice: Start with VAG-COM in basic settings, channel 11.
This regulates the load from 0% to 100% and back (in a 10-second cycle).
and keep a close eye on the VTG. If it's stuck, you've already identified the problem.

In the first case, I was able to achieve success by simply moving the plunger back and forth with a suction pump (in my case, a large disposable syringe) while the engine was stationary.
at 2. helps with cleaning or better, replacement
At position 3, you can replace the valve with the ARG valve and test it.
at 4, one had to assume that someone had "repaired" something.

Good luck
Greetings
voss