New Nozzles, Old VP: A Good Match?

I'm planning to replace the injectors on my ALH engine (180,000 km).

I'm concerned that the higher nozzle opening pressure might damage the pump. Is that likely? Doesn't the internal pressure of the pump also increase with that? Or am I mistaken?

The car has been experiencing a loss of power for some time. However, all the things that could be checked seem to be fine. The VAGcom diagnostic tool also doesn't show anything unusual. The car makes a very loud knocking sound during cold starts, vibrates noticeably, and no longer reaches its maximum speed. Additionally, there is always a significant amount of black smoke visible during strong acceleration.

I've also been driving on biodiesel for years, but for the past few thousand kilometers, I've been using regular diesel again.
So far, everything is sealed.

I have heard multiple times that, after replacing the fuel injectors, there is a noticeable increase in the occurrence of leaky or defective fuel pumps. (From Bosch service centers and truck repair shops).

What do you think about it?

Furthermore, with strong acceleration, soot is always clearly visible.
If the vehicle is in its original condition, this could be an indication of worn nozzles.

I have also driven with biodiesel for many years.
'Recent studies' have shown that biodiesel, due to its renewability...
it is a commendable energy source, but compared to conventional diesel.
It produces more pollutants (including soot or other particulate matter) during combustion in vehicles.
Nozzles that have been used with biodiesel are likely to experience more wear and tear or deposits.
Appearances.

I have heard multiple times that after replacing the injectors, there is a noticeable increase in the occurrence of leaky or defective pumps.
If, for some reason, your pump should leak or become defective - which hopefully won't happen -
Is that comparable to a faulty piston caused by incorrectly spraying injectors?
Probably the more affordable option.

Best regards.
Peter.

Yes, everything is original, with no modifications whatsoever.

What I noticed in the VAGCom diagnostic tool is that the maximum injection quantity is 37mg/H.
In another control module (I don't know which one, something related to accelerator pedal position/driver request), a target value of 43 mg/H was specified. This value is never achieved.

In addition, the AGR rate always displays a minimum value of 4.8%, never 0%, whether the AGR is defective (with a metal plate) or in its original state.

Could it be a problem with the crankcase ventilation system (leading to engine wear), or something else?

Hello!

The higher opening pressure does NOT increase the maximum internal pump pressure.
He will likely switch to the new nozzles when the hole diameter of the old nozzles becomes smaller.
That is to say, if the old nozzle holes were not widened to such an extent by cavitation that the flow resistance was reduced, then the new nozzles will not result in higher peak pressures in the pump.

Best regards, Christox.

flightmaster wrote:

What I noticed in the VAGCom is that the maximum injection amount is 37mg/H. In another MDB (I don't know which one, something related to accelerator pedal position/driver request), a target value of 43 mg/H was specified. This value is never achieved.

That's just the way the software is -> perfectly normal.

Quote:

Furthermore, when checking the AGR rate, the lowest value displayed is always 4.8%, never 0%, whether the AGR is defective (with a metal plate) or in its original state.

This is not the AGR rate, but only the control of the valve.
-> also normal.

Quote:

Could it be a crankcase ventilation issue (leading to engine wear), or something else?

No, see above.

You're welcome.
Is there a German translation or further explanation available for the individual values of all the MWB (Materialwertblatt - Material Value Sheet) entries?

flightmaster wrote:

Thank you for the explanations... Is there a German translation or a more detailed explanation of the individual values for all types of medical devices?

Yes, those are called label files, and you can usually get them from where you purchased the diagnostic cable.

The most important components are the same for the ALH engine as they were for the older Golf 3 TDIs.

So, this label file should help you.
http://freenet-homepage.de/golf-schrauber/028-906-021.lbl

You still need to rename it, because your ECU should be named 038-906-012.

Greetings.
m;

Hi flightmaster,

I suspect you're experiencing the same problem as I am. Due to wear and tear, the pumping rate of the VP37 decreases over time.
Theoretically, the flow rate is calculated by multiplying the piston area by the effective stroke. However, this is not the case in the high-pressure range. There are also internal leakage flows within the pump, i.e., between the pump piston and the pump head. These increase with wear and piston clearance. A 10% loss here means 10% less power. If you try to compensate for this, as I did, by increasing the injection time to reduce soot at full throttle, but you lose 10% of the power (as indicated by the fuel consumption display in the cockpit), the soot problem disappears.

Solution: Replace the pistons and pump head. However, mine has now reached 205,000 kilometers, and I don't know how much longer I'll be driving it. So, I'm not doing anything about it for now.

Replacing the pump head/piston, including the necessary adjustments, likely costs around €800-€1,000. For that price, I could burn through a lot of fuel.

I can confirm your theory. In my case, the fuel consumption hasn't decreased, but the performance is worse, and the MFA (Multi Function Display) showed incorrect, high values.
With a software correction of -5%, it's now accurate again, more or less.

Unfortunately, I was shocked to discover today that the hard drive appears to be slightly damp.
It seems like the ESP is actually starting to leak now. (184,000 km)

And now what...? Sealing can only be done when the part is removed. Just for that, the workshops I contacted were asking around 500 euros.

I think I'll fill up with biodiesel again and hope that the seal swells up again...

Sure, here is the translation of the text from German to English:

'MFG' is an abbreviation for 'Mit freundlichen Grüßen,' which means 'Sincerely' or 'Best regards' in English.

Quote:

It seems like the ESP is actually starting to leak now. (184,000 km)

However, it has nothing to do with the nozzles.