Lupo 3.0 TDI automatic shuts off while driving.

Hello,

I'm currently having a problem with a Lupo 1.2 TDI diesel, manufactured in 2000, with approximately 160,000 km. The car sometimes fails to start (it cranks, but doesn't fire up), or it simply turns off while driving. This happens at various intervals. Quite a few repairs have already been done, such as a new clutch, etc.

Okay, I've now checked the 1O9 relay, and it looks fine. However, I'm still going to replace it, as there can be many problems with it over time. But now, my other question: I've read a lot online about a pressure accumulator in the hydraulic unit. Could there be a connection between this and the intermittent shutdowns during driving, as well as the starting problems...?
Error memory is empty.

And if so, what's the best way to replace the pressure accumulator, especially since I'm currently traveling abroad? Please provide an urgent response. Thank you.

Does the preheating light come on briefly during the start-up attempts?

If that's the case, injector 109 is likely very far forward, and that could be the reason it fails during operation because the engine control unit then no longer receives power, preventing the PD injectors from opening.

Before expensive swapping sprees begin, here's my tip:

Here, people are genuinely trying to help, but since none of us are physically present to assist you directly, you are the eyes and ears of the readers here. Please try to find exact data, have the error memory read out (using a diagnostic scan), and post the data here precisely (ideally using VCDS). Depending on how long you plan to keep the vehicle, and whether you might buy another VAG product afterward, this can be a cost-effective solution in the long run.
If we start guessing here, our assistance unfortunately won't be very reliable.

Have you all read out the ECUs?
"That part should already have CAN functionality. If it were relay 109, we would expect to see communication errors related to the master control unit (MSTG) in other control units (ABS/ESP, instrument cluster, transmission)."

Hello,

Thank you for your help. I will have the error memory read out again at VW, as I don't have my VAG-COM available. However, it was already read out recently and was completely empty. But I'll check it again, just in case there's something new.

I would also like to know if a defective hydraulic accumulator (for the clutch) can cause the engine to stall while driving, or if it only causes shifting problems.

Since the car otherwise shifts and drives perfectly.
I'll keep an eye on that preheating coil.
I once opened a relay and didn't find anything unusual regarding the solder joints.
Today I'm getting the new relay from VW.

The strange thing is that sometimes I can drive the car for a whole week without any problems, and sometimes it just dies every 5 kilometers and then restarts at different times. Sometimes it restarts immediately.

Best regards.

Hello,

Okay, the error memory is clear again.
Relay 109 replaced, but the problem persists.
Question: Can a pressure accumulator cause the engine to completely shut down?

Best regards.

Find the pin assignments for the engine control unit (wire colors) and connect LEDs to the power supply of the engine control unit using current-limiting resistors. Run the LEDs into the interior of the vehicle.

Then you'll know whether the problem lies with the control unit, various sensors, software bugs, or simply a lack of power.
I'm leaning towards the latter.

Best regards, Rainer.

Thank you for the tip.

I will obtain the wiring diagram and then see what emerges. I would really like to know, since there is a lot of discussion online about the pressure accumulator in the hydraulic system for the automatic transmission, whether this pressure sensor (i.e., if the pressure accumulator is defective) sends a signal that simply SHUTS DOWN the engine... or whether it only prevents the transmission from shifting.
Unfortunately, I don't have a schematic diagram available right now that shows how the pressure sensor is wired.
Perhaps someone has experienced a faulty pressure accumulator before, and the engine shut down as a result, or maybe not...

Best regards.

..without realizing it, the probability that an error will directly shut down the engine is very low, as this would be dangerous!

matthiasTDI96 wrote:

..without knowing it, the probability that an error will directly shut down the engine is very low because it is dangerous!

I see it the same way.
It might also be due to the crankshaft speed sensor. Some ECUs don't register it as an error.

Hi,
Thank you for your help. I will continue searching, and if I find anything, I will report the results here.

I might also replace the KW sensor at the same time. It usually shows up in the error memory, but maybe it's different with the Lupo...

Best regards.

luiggi wrote:

It usually shows up normally in the error memory, but maybe it's different with the Lupo...

As I said: I've had it several times where it wasn't present and was defective.