Idling speed control 85kW PD /AJM

Hi everyone,
I've been driving a Bora PD for 90,000 km and I'm experiencing problems with the idle speed control.
'Since I have only ever used biodiesel, and the documents explicitly state that the engine is approved for it, VW is now claiming that I have damaged the fuel injection pumps.'
The diagnosis states that the target value per stroke should be +/- 2.8 mg/H, but the actual value is 20 mg/H. The engine delivers good power, but there is no smooth running when idling. Cylinder 2 shows -0.18, and cylinder 3 shows +0.18. Before potentially replacing an injection pump, I would like to know if there might also be a sensor that is defective, and how I can determine that .

So, a PD (presumably referring to a rotary injection pump) doesn't have an injection pump in the traditional sense.

What are the exact values for each cylinder in the LL (Low Load) control system?

0.18mg/H would be an extremely small amount...

When was the diesel filter last replaced?

Hi, and thanks for the quick reply.
First, I noted the value displayed by the diagnostic device. I interpret the reading of 0.18 as 18 mg/H.
The filter was replaced only about 3000 km ago, and there hasn't been any noticeable change in the engine's running smoothness since then. To supplement this information, the first and fourth pots are priced at 0.06.
The workshop colleagues now want to check the injection timings first, as they suspect that something might have gone wrong during the timing belt replacement (30,000 km ago).

No, 0.18mg/H is not the same as 18.0.

They should start by checking the injection timing; they might have also misaligned the belt. Have you experienced any issues with starting (hot/cold engine), acceleration, or top speed since the belt replacement?

Okay, they're checking the injection timing now.
The belt replacement was done at the 60,000-mile service.
Regarding the values: 0.18 is the reading provided by the diagnostic system for cylinders 2 and 3, while it's approximately 0.06 for cylinders 1 and 4, representing the control difference during idle speed regulation. However, the total dosage specified for all cylinders is +20mg/H, which is what makes us suspicious and raises the question of where this value originates.
Besides the idling issue, there are times, regardless of the engine temperature, when the machine runs smoothly, but the jerking or stuttering is more prevalent.

KoeAnd wrote:

However, the total dosage for all cylinders is specified as +20mg/H, which is what makes us suspicious, as we don't know where this value comes from...

I'm initially interested in knowing which measurement block this value originates from .

Okay, the timing check paid off. The timing belt was installed on the 60,000 sender by simply shifting it one rib. This was then covered up by pushing the pulley with its elongated holes all the way to the stop, instead of using it for final fine adjustment.
Tomorrow, my new workshop will fix it, and hopefully, it will work then.
Thank you for the tips...