Golf BKC Idle Speed Control - Troubleshooting

"I'm having a problem with this golf; the engine isn't running on all cylinders, and it's worst right after a cold start."

Address 01: Engine Control Module (03G 906 016 Q)

15:51:23 Block 013: Idle stabilization (fuel injection deviation).
-2.75 mg/H Mengenabweich. Cylinder 1.
2.99 mg/H Mengenabweich. Cylinder 2.
-2.47 mg/H Mengenabweich. Cylinder 3.
0.07 mg/H Mengenabweich. Cylinder 4.

These are the values with a cold engine; with a warm engine, I only have +2.56 mg/H on the second cylinder.

The previous owner already had some work done on the car.
Turbocharger and intercooler replaced.
Dual-mass flywheel + clutch.
PD elements sealed.
PD line renewed.
Reciprocating pump.

First, I measured the compression, which was 36 bar in all cylinders. Then, I bent the pins of the piezo injectors to improve contact (at that point, I didn't know that the fuel line had already been replaced). This didn't work.

"Then I swapped the PD elements with new seals, but the problem persists on the 2nd cylinder. The values in the MWB 23 are very good, only ranging from -10 to -20."

I couldn't detect any wear on the camshaft or tappets. In my opinion, the valve seats for the PD elements are also okay. I haven't had any problems with those that have copper sealing washers.

The only thing I've noticed is that all the PD (positive displacement) impellers have a pressure point. Either the previous user didn't adjust the collision margin correctly, or I can't think of any other explanation. But if that's the case, the impellers should have been damaged.

Hello,

The pressure marks on the PD lobes likely originate from a completely incorrect setting, followed by an attempt to start the engine.
How pronounced are the pressure points, and can they be assessed using measurement techniques?
A half-turn when adjusting the P and D elements already makes a significant difference...

I would smooth out the pressure marks as a "quick fix."
After that, adjust the setting on the PD element with the smallest amount of power required.
Adjust all other PD parameters in the settings (which affects the amount of boost) and then reduce them until the values for the idle speed control are reasonably close.
So, set the settings back between 180° and 360° (for all other readers: there is a technical article on how to adjust the PD elements).


Best regards, Rainer.

Thank you, Rainer, for the suggestion. I'll give it a try. I usually rotate it 270 degrees back, as was the standard practice in the past.

I can't really tell if the pressure mark on the second cylinder is larger than on the others. I've attached a picture of the first cylinder.

Quote:

I usually turn back 270°, as was the standard practice in the past.

It does, however, come at a cost. Just kidding, it's almost irrelevant in terms of performance.

Okay, I've now replaced the camshaft and the lifters. On the second cylinder, the valve could be pushed down by the rocker arm, and now the idle speed control is working properly again.
Now, I just need to find the error that's causing the LD (Load Dump) issue at lower RPMs. https://community.dieselschrauber.org/en/viewtopic.php?t=30622 Third post.

Thank you for the feedback .