AJM Passat: Intermittent Engine Misfire

Hello fellow mechanics!

Mein 3B AJM macht wieder einmal seltsame Sachen und das nur ganz selten. Meistens bei leichten Steigungen im vierten Gang fängt es plötzlich ganz langsam an zu ruckeln und wird dann immer heftiger. Dabei verliert der Wagen an Geschwindigkeit und die Leistung geht drastisch zurück. Nach circa zwanzig Sekunden beginnt die Kühlwasser Temperatur zu steigen und geht über die 100 Grad Markierung im Kombiinstrument. Dieses Phänomen tritt vielleicht alle 500m bis 1000 Kilometer einmal auf und lässt sich weder reproduzieren noch absichtlich herführen. Eine Fahrt auf der gleichen Strecke mit einem Anhänger mit 1,5 to führt nicht zu dem oben beschriebenen Ruckeln, dieses tritt nur ohne Anhänger auf. Die Temperatur hat auch keinen Einfluss auf das Ruckeln, einmal ruckelt es bei 15 Grad ein anderes mal bei 30 Gard Aussentemperatur. Fehlerspeicher ist natürlich leer und in den Notlauf ist der Wagen auch noch nie gegangen. Laut LDA ist bei diesen Ruckelaktionen der Ladedruck bei konstant über einem Bar Ladedruck. Eventuell hat dieses Phänomen auch was mit meinem schon seit längerem bekannten Problem mit dem Kühlwasserverlust zu tun oder es ist eine Folgeerscheinung. KiThe mileage is 186,000 km, and the PD elements may be somewhat worn, but they are still within the tolerance range.

Regards,

hb2000

hb2000 wrote:

It usually starts with a slight jerking sensation when driving uphill in fourth gear, and it begins very slowly but then becomes increasingly severe.

At the same time, the car loses speed and the power drastically decreases. } After about twenty seconds, the coolant temperature starts to rise and exceeds the 100-degree mark on the combination instrument. }
Hi,

Have you encountered that plateau effect in the temperature display, where it typically stops changing (regardless of whether you're using full throttle or coasting downhill) once it reaches the 90-degree mark?
Then, the display shows approximately 110°C when it's actually around 100°C, and I can't imagine how you could push a 1.9 TDI engine block to the point of overheating so quickly, even on slight inclines!
-> I suspect there's a more general electrical problem that's also causing the AI to malfunction... perhaps a grounding issue?

Does it have a coolant leak? Or is it overheating? You don't mention anything about that. If it's that hot, do you turn it off to let it cool down and then check the coolant level? What does the expansion tank say? Because Ulf's theory could very well be correct.

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Does it have a coolant leak? Or is it overheating?

Look here: https://community.dieselschrauber.org/en/viewtopic.php?p=84038&highlight=#84038

That pretty much says it all, doesn't it?

Let's see how long this engine will last.

Hello.

That pretty much says it all, doesn't it?

That was also a topic I was interested in .

Let's see how long the engine will last.

So far, 50,000 km with the coolant issue.

I'm leaning more towards some kind of overarching electrical problem that's also causing the AI to malfunction .

I can rule out an electronics problem - it really gets that hot .

Have you already implemented that plateau function for the temperature display...?

My AI already has the 'calmed' version of the temperature display installed.


My current problem is the stuttering/jerking, and how it occurs, or what is causing it and where it's happening.

By the way, the coolant isn't burned; it's pushed out through the exhaust gases.

Regards,

hb2000

Quote:

That used to be my topic as well icon_biggrin.gif

I know that's why I included the link, so users can get a general idea of the engine's performance.

Quote:

By the way, the coolant is not burned, but rather pushed out through the exhaust gases...

It's sad that you know the main problem but aren't addressing it, and instead you're focusing on a relatively minor issue (possibly a secondary effect).

If the ZK (likely referring to a component in a cooling system) is leaking, the area where the air bubble forms will become significantly hotter than what the coolant temperature would suggest.

I can imagine that, with such extremely high temperatures, some components might start to malfunction.

Don't be surprised if the engine eventually gives out due to overheating.