AUFLÖSUNG auf S. 2 - TDI AFN - Mengensteller oberer Anschlag | Posts 16+

Hello,

Quote:

Rainer, you wrote that the error "quantity adjuster, upper limit" can also be caused by this, and I suspect that the quantity adjuster has been shifted axially towards the HD part. Would that be plausible?

I only remember that the error sometimes occurred with adjustable/loose quantity setting devices... I've forgotten whether it was the upper or lower limit that was affected.

Best regards, Rainer.

Hi,
The question is, what kind of pressure does the pressure sensor read when the ESP is assembled?
The metering piston control ring has a mechanically limited stroke, but the torque motor in the metering unit also has its minimum/maximum limits.
My assumption is that the self-diagnosis of the fuel injection system refers to the latter. Ultimately, however, you can only find out for sure by taking a closer look at the pump.
The usability of the MSW setting can be somewhat assessed by looking at the values of the sensor for RSW during ignition (MWB #1, value 3) and for EM (MWB #1, value 2) at idle with a warm engine.
For the RSW voltage, it's 0.7V to 0.74V, and for the EM, approximately 5 mg per cycle. Assuming the motor doesn't have another issue. What happens to the RPM when you initially accelerate to around 2500 RPM and then release the throttle? Does it immediately drop to the target value (approximately 860 RPM), or does it go through an intermediate stage?
Based on your description, I would rule out a severely misaligned MSW (magneto-spark wheel), as that would likely cause the engine to have starting problems or to run roughly.
hg
Herbert.

Thank you both! I don't have the car here right now, but the RPM definitely drops with the swing arm, as you can see in the intermediate stage. It's wave-like, if you want to describe it that way.

It's just a very slight swaying motion, so not a strong jolt in the car body, but it's definitely noticeable by the sound.

I need to check the MWB.

Hi,
This suggests a slightly too aggressive setting, which would mean that the actual engine speed (displayed in VCDS) is a bit too low. Let's wait and see what the actual numbers are.
hg
Herbert.

Herbert wrote:

Hi, This suggests a slightly too rich setting, and consequently, the AFR (Air-Fuel Ratio) displayed in VCDS would be somewhat too low.

That's also my recollection of the AFN.

Quote:

Let's wait for the numbers.

I would do the following: Unscrew the pump cover again, connect VCDS, access module MWB1, manually push the RWG to its stops and observe the voltage in MWB1 while doing so.

If the voltage levels are within the specified tolerance ranges, then everything is okay.

If they are located very close to one of the boundaries, even the mounted pump cover can push them into the error range (or the usual temperature drifts caused by weather and engine operation) -> readjust the RWG (presumably referring to a specific component or setting).
The fixed part determines the spread between the minimum and maximum clamping force. And twisting the arm on its axis shifts this spread up or down on the tension scale... clear?

Okay, so by combining a measuring ring and a reference ring, you're essentially shifting an entire spread within the measurement field/measuring ring, which is then interpreted as voltage by the control system?

The relay engages when "ignition is on," retracting the limit switches. Are you sure that I can manually operate the rotary valve without any, even slight, magnetic counter-force from the coil?

Could you please provide the reference values for MIN and MAX again? Thank you! I won't be able to check that until next week.

Does a misaligned setting indicate that the quantity adjuster has shifted towards the high-definition (HD) side, or is the axial displacement unrelated to this?

I'm slowly getting confused, sorry about that...

EDIT: It seems it might be so...

QUOTE FROM ULI:

The displayed amount is the injected, counter-flow value:

"- The display indicates an excessively high injection quantity: In reality, the injection quantity is too low; the adjustment mechanism on the injection pump must be moved towards the high-pressure side."
Source: https://community.dieselschrauber.org/en/viewtopic.php?t=5517

This means that your initial fuel setting is too low after the adjustment, which is causing the engine to start poorly. The solution is to readjust it to the original value or experiment until you find the right amount that provides verschandeln combustion, smooth operation, and quick starting. I only experience rough running with the AFN engine below 1800 RPM and with a high fuel mixture. The injectors have 0.216mm nozzle openings. Perhaps the problem is something else? Maybe the NHG (presumably a part or component) was damaged during the injector replacement?

Hi,
We discussed the reference values earlier (if 1Z and AFN are comparable). Please note that the displayed values can be slightly different with the cover on and with the cover off, as the cover affects the magnetic field. The values with the cover on are the definitive ones. However, you can determine the voltage difference (approximately 0.2 V).
"If you're getting 4mg in idle warm, that's not really bad. You can initially improve this through adaptation on channel 1 (see technical article). After the MSW cleaning, I also adjusted it until I reached 5mg +/- 0.5. However, it probably doesn't depend solely on the value itself, but on the entire configuration. That's why I'm asking about the min/max values for the RSW voltage."
I'm not sure about the magnetic counter-force when twisting with the ignition on. However, it's possible that the fuel injection control is trying to keep it at zero.
hg
Herbert.

Deus Violentia wrote:

Ah, so, by combining the measurement and reference rings, one shifts an entire spread within the measurement field/measurement ring, which is then voltage-interpreted by the control system?

You probably mean something close to that.
If the difference between the displayed values is so small or so large that at least one voltage must always be outside the minimum and maximum tolerances, then the reference ring must be readjusted in any case.
If the difference between the displayed readings corresponds to the distance between the setpoint fields, then an adjustment of the measuring ring may be sufficient.

Quote:

The motor, when in the "ignition on" state, retracts the stops. Are you sure that I can manually operate the RWG without any, even if small, magnetic counterforce from the coil acting on it?

It's possible, but I've never tried it.
As long as you can overcome the opposing force without applying excessive force that could damage the material, I don't see any problems other than a potential error message.
Based on the circuit design, I suspect that the magnet can only open the MSW (mechanical switch), while the spring is responsible for closing it.
An active magnetic attraction force towards zero would, in my opinion, require a polarity reversal of the magnetic switch (MSW), but that is fixed to 12V with 1 pole, if I recall correctly.

I once took a close-up picture of the VP37, focusing on the ring joint of the inlet pipe; you can clearly see the displacement of the flow control valve, I think. The scratch mark is also not mine, and I only noticed it yesterday.
I was unable to observe such a significant shift towards the high-definition portion in two other vehicles equipped with VP37. The VAG-COM values are not yet available...

Solution:

Despite the clear visual inspection, the quantity adjuster was found to be full of shavings.
After a complete renovation, the problem is gone.

KW stub and ZR wheel worn out, but only visible after disassembly .
Have it planned and a new timing belt wheel installed.

It seems things are going well now, THANK YOU FOR YOUR HELP!

"Long-term report" - The engine is still running consistently well!