PD Unit Power Issues: Troubleshooting Stuttering

Best regards from Carinthia, Austria, to all members of the TD community forums. I'm new here and have been searching for answers to countless questions I've had for the past three weeks (I bought a Passat 3BG TDI 74 kW (AVB) Variant just before Christmas) and have also found many helpful posts.

Habe bei meinem Passat 74 kw PD Diesel (AVB) folgendes Ruckeln: es trat bisher nur in der Warmlaufphase (nach ca. 10 min od. 10 km) auf - und nur beim Beschleunigen zw. 2500 und 3500 U/min. Es handelt sich dabei um ein 'weiches' ruckeln (als ob zu wenig, oder kein Diesel eingespritzt wird). (Anmwerkung: ich erreiche auch nur eine Höchstgeschwindigkeit von 170 km/h bei ca. 3600 U/min im 5. Gang)

The following actions have already been completed:


at the
- Troubleshooting (no entry, MAF sensor measurement OK).
- The AGR valve was also deactivated there.
- new fuel filter
- new air filter

'I tried installing a replacement mass airflow sensor (MAF) that was 6 months old (obtained from a friend). This did not result in any improvement or change.'

'Since the jolting had only been brief so far, I left it at that. Today, I drove fully loaded for lunch for the first time. After about 8 km, I wanted to accelerate on the highway. The jolting occurred again, and then the ESP warning light came on and stayed on. It felt like a cylinder had failed, or the car was only running in a limp mode. At the next rest stop, I turned off the engine and then restarted it, and the ESP warning light went out.'

After that, I drove to the ÖAMTC (which was conveniently located on the way) to have the error codes read. The following entries were found:

VW Diesel EDC 15P fault memory:
- 469A Valve for Pump-Nozzle Unit, Cylinder 1.
Circuit error.

VW ESP 1.34 error memory.
- 4759 CAN-based message for the engine control unit.
Engine torque implausible.

During the test drive with the mechanic, everything went completely normally (just like it did back then with the ). He cleared the entries in the control unit - he couldn't do anything more .

Has anyone experienced these issues before, or does this sound familiar to anyone? I would appreciate any advice.

Greetings, bertl7.

Greetings!

I wanted to check if your problem has been resolved? Based on how you described your issue, it might be the same as mine. I'm about to lose it. I've now been to the 3rd workshop, and no one, not even the Audi authorized service center, could tell me what the problem is. I've found some similar posts, but nothing concrete has come out of it! It would be great if you could share your experience with me!

I would like to take a closer look at and test the control cable for the pump-injector unit on the first cylinder. It's quite possible that there's a loose connection or a high resistance somewhere, which could be the cause of the engine misfire.

Hello!

Okay, I'm bringing this topic up again!

I'd be interested to know if there's a viable solution to this problem now, which seems to occur quite frequently with AVB engines. My car, a Passat 3BG Variant 1.9 TDI engine: AVB 74kw, has the same symptoms as the one described by the thread starter.

I would be very grateful for your experiences and feedback!

Quote:

I would like to take a closer look at and test the control cable for the pump-injector unit on the first cylinder - it's quite possible that there's a loose connection or a high resistance, and that's causing the jerking.

That's quite possible. I would swap PD1 and PD2 to see if the error follows, in case it reappears later.

Okay, I just drove a longer distance on the highway again! After about 15 km at a speed of 180 km/h, it started shaking again, and the ESP warning light came on. The shaking was present in every gear, and acceleration was no longer possible.

After turning off the engine and restarting it, it ran reasonably well again. However, the jerking was still present, albeit in a milder form. After driving for a few kilometers at 100-120 km/h, it ran perfectly again, without any jerking.

Hello,

Please check the PDE head connector and the central connector on the head for the PDE. Also, check all the cables for continuity and resistance.
Do you happen to have a clamp meter? If so, could you please measure the BIP (Basic Insulation Performance) for each individual PDE (Power Distribution Element)?
If everything is okay, please let me know.
Best regards and good luck.

Hello!

Is it known whether the power distribution board (AVB) is prone to PDE (power distribution element) failures, or is it usually due to problems with the wiring harness?

Well, a PDE (positive displacement element) can indeed fail. You could try swapping it with a 2-cylinder or 3-cylinder element, and if the element is faulty, the error should follow the swapped element.
As I said, it sometimes happens that the component breaks, but it's rare.

Sooooo...

Here's what came out of today's workshop:

PDE Cylinder 1.
Circuit error.

Okay, so I'm going to assume that the wiring harness, from the cylinder head to the injectors, is completely broken.

Could any of you possibly provide me with the part number for the wiring harness?

Hello.

038 971 600 Adapter wiring harness fuel injector 42.66 € including VAT.

However, the dealer should also know .


Best regards, Charly.

Great, thank you!


I hope my problem is solved with that .

Okay, so I'm going to assume now that the wiring harness from the cylinder head to the injectors is completely broken.

Hello.
I've previously suggested that these errors might be caused by 'incorrect' wiring. Regarding the price of the wiring harness, I'm assuming that silicone wiring is not being used. Please correct me if I'm wrong.

If I'm correct, the problem is that 'normal' vehicle-suitable cables are only specified for an ambient temperature of up to 125°C. If the current flowing through the cables is low and the cross-sectional area is large, this temperature range can be extended.
Given that temperatures inside the head can sometimes exceed 140°C (based solely on the oil temperature, which, as is well known, is not measured at the hottest point), IMA silicone hoses with a temperature resistance of 180°C should be used.

Best regards, Jochen.

Jochen_145 wrote:

If I am correct, the problem is that "normal" vehicle-suitable cables are only specified for an ambient temperature of up to 125°C. If the current flowing through the cables is low and the cross-section is large, this range can be extended. Since the temperature inside the head can sometimes exceed 140°C (based solely on the oil temperature, which, as is well known, is not measured at the hottest point), IMA silicone hoses with a temperature resistance of 180°C must be used.

From now on, everyone who reads this thread should pay attention to any deformed or melted cable insulation in the area of the ZK cover when replacing the PDE wiring harness, and document any such findings with a photo!

The problem with the PDE (Pressure Differential Encoder) cabling in the head unit is that, due to motor vibrations, the connectors can move within their guides, which mechanically damages the cable connectors and contributes to malfunctions. Check that the connectors are securely seated and measure the connector strip; if you find any abnormal readings, replace it.
I have never personally experienced or seen burnt-out plugs or anything similar.

Best regards,

Due to motor vibrations, the connectors in the PDE housing can move, which can mechanically damage the cable connectors, contributing to malfunctions.

If mechanical damage to the connectors occurs due to vibrations, these effects should be calculated or otherwise assessed.
If the connectors are deformed and this causes contact problems, this can also be explained by thermal effects.

I have never personally experienced or seen burnt-out plugs or anything similar.
If it comes to that, you have more than just a problem.
Back to the idea: I see the performance, not the connectors, as the problem.
Due to the degradation of the insulation, short circuits or similar issues can occur.

As described above, the wiring harness was replaced, not the connector.

Best regards, Jochen.