Beschleuningsaussetzer beim 1,9 PD TDI 85KW (MKB AJM) | Posts 32+

Bertil wrote:

Ulf wrote: In my opinion, the problem with the fuel pump should also be diagnosable based on the diesel temperature. The problem here will be the environmental conditions. If it's cold outside, you get a completely different measurement than if it's warm.

Yes, unfortunately... but let's try a different approach:

Steam bubbles in the pressure drop element (PDE) can lead to a loss of performance.
Werden sich in allen PDE immer gleichgroße Dampfblasen sammeln? In my opinion, probably not.
Consequently, the idle speed control system would become disrupted, and the more this happens, the higher the engine load and outside temperatures are.
It is possible that the switching times of the PDE are also exceeding their tolerance limits simultaneously.

Both can be read out using VAGCOM (at the authorized service center: control modules 13 and 23).

So, if...
-> MWB 13 and 23 values are normal when the engine is cold/slightly warm, or under partial load.
-> Jerky behavior related to engine temperature and load is becoming more pronounced, while the MWB 13 + 23 sensors are also malfunctioning significantly.
In that case, it is likely that the tandem pump is not performing adequately, and a pressure measurement using a manometer seems advisable (similar to a "Hoppel test" and a proper compression test).

It might be possible to further confirm the suspicion before taking a pressure measurement by temporarily disconnecting (removing the fuse) the pre-injection pump. This could exacerbate the problem of air bubbles caused by a worn tandem pump, as it would further reduce the circulation of diesel fuel.

Would you support these ideas for an entry in a "Common Mistakes" article, or am I missing something in the logic?

Could the same symptoms also be caused by other issues?

ulf wrote:

Would you support these ideas for an entry in a "Common Mistakes" article, or am I missing something in the logic?

I prefer this approach.

Quote:

Or could the same symptoms also be caused by other errors?

I cannot assess the problem because I have not encountered this error before. The entire explanation is purely theoretical and would first need to be "tested" in practice.
Nevertheless, I would like to include this explanation as well.
In any case, this issue might be relevant to our original thread.

Bertil wrote:

ulf wrote: Would you support these thoughts regarding an entry in the "Common Mistakes" section of the article, or am I missing something logical somewhere? I like this approach better.

OK, I've added it to the article.

Now the question is how and under what conditions the desired pressure value is measured.

Michael II once posted a similar error message (linked in the "Common Errors" article), but unfortunately without these details .