SOLUTION on page 2 - TDI AFN - Quantity adjuster, upper stop

Evening, guys.

Despite having studied the relevant forum posts and articles, I have a question:

Am I correct in assuming that the error...

Quantity setting, upper limit.

Can the VP37 error only occur due to a faulty or stuck quantity meter, as is usually stated? Or can the control unit also trigger such an error under other circumstances?

The fuel pump was adjusted with a gauge after the timing belt replacement (engine overhaul!), and the starting behavior and idle speed are fine.

However, there is a lack of performance and this error in the system.

I think the problem might be with the quantity adjuster because the motor has been on the pallet (not with me...) for at least a year and a half. The next step for me is to run a bottle of Liqui-Moly diesel cleaner through the pump, using both the forward and return lines, with a single bottle.

Any other brilliant ideas?

Hi,

It could also be due to the position (offset) of the point machine.

Basically, it could be anything that prevents the pump from reaching its upper limit (e.g., wiring harness, flow meter) or that alters the feedback signal accordingly (e.g., wiring harness, potentiometer, or Hall effect sensor, such as water or debris in the ESP system).

Best regards, Rainer.

Can I bleed the pump by using the central screw located in the middle of the four injector lines on the distributor block while it's running? Is that advisable, and what's the best way to proceed?

If the error is caused by a blockage due to debris, what is the likelihood that I will see something if I disassemble the metering unit from the pump after marking its position?

Am I correct in thinking that I could try shifting the quantity adjuster a few 1/10mm towards the distribution body, or was it exactly the other way around?

Hi,

Quote:

Can I bleed the pump by using the central screw in the middle of the 4 injector lines on the distributor block while it's running? Is that advisable, and what is the best way to proceed?

In the correct position, yes. I would simply apply strong suction at the return line.

Quote:

If the error is caused by a blockage due to debris, what is the likelihood that I will see something if I disassemble the metering unit after marking its position relative to the pump?

Very likely. Before that, please check the plug/cable, etc. connected to the pump and note the values for the lower and upper limits.

Quote:

Am I correct in thinking that I could try shifting the quantity adjuster a few 1/10mm towards the distribution body, or was it actually the other way around?

Good question. To answer that, I'd need to see how the mechanical stop is designed; I don't know the answer off the top of my head. Theoretically, a shift to the right (towards the conductors) should decrease the voltage value from its upper limit.

Best regards, Rainer.

Hmm, so I bought some "Atomspritze Leningrad" and sucked down a couple of hundred milliliters...

The connectors have been checked, as well as the continuity/resistance to the control unit; everything is OK.
Similarly, the resistance and continuity values of the electronic pump elements must comply with the specifications of the relevant VAG-RLF (presumably a standard or regulation).

Hi,
I don't think anything can be achieved by changing the set quantifier. The current through the quantity adjuster and the signal from the RSW sensor should remain unchanged, as only the deflection of the quantity adjuster ring changes.
If nothing seems to be stuck, perhaps recalibrating the RSW transmitter might help. As I understand it, when the test is run after turning on the ignition, the minimum/maximum value of the quantity setting is reached, and the feedback from the sensor is checked.
The target ranges for the voltage of the RSW sensor are known.
hg
Herbert.

Hello,

Quote:

I don't think anything can be achieved by moving the set quantifier. The current through the quantity adjuster and the signal from the RSW sensor should remain unchanged, as only the deflection of the quantity adjuster ring changes.

I thought so too. However, I seem to recall that the start-stop values shifted. Unfortunately, I don't have a pump that I can disassemble and inspect.

What are the start-stop values?

Best regards, Rainer.

I am referring to my 1Z. According to the manual, the MWB 19 should provide a voltage of 0.6 - 0.9 V at the bottom and 3.8 - 4.4 volts at the top when ignition is on. If, in addition to tolerance, either transition resistances or MSW (Maximum System Voltage) are adjusted (according to the manual).
I can't see it on my car; my control unit isn't providing MWB 19 yet.
(I didn't intend to move the measuring device anyway ).
Looking at the two technical articles (cleaning the MSW, disassembling the high-pressure section), it appears that the movement [of something] should not have any effect. The mechanics of the MSW (presumably referring to a game or system) remain largely the same, in my opinion.
hg
Herbert.

Okay, thank you for the feedback!

Since it appears that the upper limit will not be reached, the following measures will now be implemented:

1. Liqui-Moly Flush.
2. Optical "span test".

I will report!

The flushing process didn't work, so we're now moving on to testing the "mechanics."

Hi,
Perhaps fill the ESP reservoir again with LM, remove the lid of the ESP, and carefully move the quantity adjuster and, consequently, the quantity adjuster ring by hand, from stop to stop. It's possible that the quantity adjuster ring is stuck. At least with the method without dejustage, you're checking the mechanics.
hg
Herbert.

You mean I can manually rotate the knob of the potentiometer from stop to stop and then reinsert it?

Deus Violentia wrote:

You mean I can manually rotate the knob of the potentiometer from stop to stop and then reinsert it?

Yes, it should normally be possible without any problems.

Hi,
To remove and reinstall it, you only need the MSW cover. Simply adjust the quantity setting by hand, feeling for the correct position, by turning the knob on the shaft after removing the cover.
hg
Herbert.

edit: just to be sure - before and after removing the cover, with the ignition on, record the value 3 (voltage of the RSW sensor) from MWB 1. If the holding screw and sensor unexpectedly come loose, you will have a reference for adjustment. See. Instructions for cleaning the MSW (Municipal Solid Waste).

I will definitely try to do that! Thank you for the tip!

Okay, yesterday I went all out.

Intake manifolds, injectors, and turbochargers:

Cleaned the intake manifold, disassembled the VNT15 turbocharger and completely cleaned the VTG (Variable Turbine Geometry), and resealed the fuel injectors with new copper rings (because there was something strange about them in the cylinder head, and I wasn't sure if someone had removed them before without replacing the rings).

VP37 quantity adjuster

I removed the cover of the VP37 and manually moved the adjustment knob.
Result: No snagging, consistent feathering force from left to right, and a firm impact. Okay, I put a new gasket on the fuel injector and reassembled it, then filled it with diesel using a syringe.

Vacuum sensor VTG

Then I noticed something else that I hadn't seen before: The vacuum chamber, for some reason!, is bent and doesn't extend all the way to the adjustable stop . However, the test with the syringe showed that it still regulates "smoothly" without sticking, but it tends to get stuck rather than reaching the stop. So, another new can is going to be added.

I also noticed that some kind of vandal probably moved something, because the yellow sealing wax on the screws at the bottom of the signaling equipment is missing, meaning the screws were exposed.

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

Regarding the starting and current driving behavior:

The cold start went smoothly after the assembly, but a slightly longer idling period (1 minute) was necessary because I had the injector nozzles removed and the pump was open.
Since I had, following Ulf's advice in the technical article, refilled the VP37 with diesel using a syringe through the inlet side after mounting the cover, until diesel came out of the return side, everything was very straightforward.

Warmstart

Unfortunately, I didn't have a VAG-Com device available. The idle speed is stable, the engine starts perfectly when warm; it only needs to be left running for a second before it runs smoothly.
The performance is significantly better than before, but it's still not an AFN (Advanced Fuel Nozzle), more like a 1Z.

After 15 hours of work, I was about to go to bed at 1 AM, but I felt like tinkering with the pump again and seeing what you all think!

Thank you very much! [/b]