Recognizing Early Signs of PDE/Injector Damage

Hello,

What is the best and most suitable method for detecting (initial) damage in common rail injectors, as well as in normal fuel injectors?

Thank you very much!
Best regards.
Alevuz.

Injector nozzle test bench.

Hello,

Thank you for the information, but overall, I will not expand 14 PDUs based on suspicion and will instead take them to the Bosch service center!

"Put differently:"

*How effective is the idle speed control in this case?*
"Is it possible to read out and log the injection quantity per injection and for each individual PDE?"

Background: Some damage, specifically to the V10/R5, related to the peeling of the plasma coating, seems to me to be more likely caused by nozzle damage... at least in the last one I saw, which was a BLE model and not an AYH (so the LL2 discussion is irrelevant). One piston was severely corroded and melted on the surface, while the spray pattern on two other pistons was unacceptable.

Thank you in advance for any responses you may provide.
SG, Alevuz.

Hello,

That practically calls for a technical article about checking the different injection systems, namely VP, PD, and CR.

I believe many basic tests can already be performed using standard workshop tools and the diagnostic functions of the engine control unit.
If the results indicate specific damage, it makes sense to remove the fuel injectors and, for example, test them on a test bench or have them repaired.

[Edit area start]
Okay, I'll start with VP:
- Check the idle speed control. Since this only displays differences in injection amounts between individual cylinders, it is not initially possible to distinguish between even wear of the injectors or different compression in the cylinders.
In cases of significant deviations in the LLR (lung compliance ratio), compression differences should first be ruled out, for example, using a Hoppel test.

PD: As above, still need to check for any deviations in the closing time for the BIP. Measure fuel pressure. What is the lambda value under full load?

CR: As above, check for injector timing deviations. Lambda value at full load?

...

[Edit area end]

Best regards, Rainer.

Are there any ranges of values that are still acceptable for the LLR?

In the VCDS label files, I don't find any information regarding absolute values, at least for my BPW system.

voodoo wrote:

Are there any ranges of values that are still acceptable for the LLR?

Hello...

I once read something about values ranging from -2.9 mg/H to +2.9 mg/H... I wonder if that's correct? And that all the values together should ideally add up to zero...

What strikes me as particularly noteworthy is when one or more data points deviate significantly from the norm, or when an "out-of-trend" result is observed.

For the Golf, all 4 were in a new condition at approximately +/- 0.3 mg/H, but now at 150,000 km (approximately 93,000 miles), they are at approximately +/- 0.6 mg/H. The same applies to the "Dicken" (presumably another vehicle), where all are at approximately +/- 0.7 mg/H.


SG
Alevuz.

voodoo wrote:

Are there any ranges of values that are still acceptable for the LLR? In the VCDS label files, I don't find any information regarding absolute values, at least for my BPW system.

-2.8...+2.8 mg/dose

Best regards, Rainer.

Is the mechanical condition of the engine still unknown, or am I mistaken?

Are these "indicators" really sufficient for a reliable assessment of PDs (regarding early signs of damage)?

BM wrote:

Does the mechanical condition of the engine still remain unknown, or am I mistaken? Do these "clues"

really provide enough information for a reliable assessment of PDs (regarding early damage)? }
Hello BM,

No. If your car a) has even compression across all cylinders, b) shows a noticeable misfire on one cylinder, and c) exhibits significant timing variations in the corresponding common rail injector, what would you do next?

Best regards, Rainer.

Quote:

If your car a) had uniform compression in all cylinders,

We need to verify if that is actually the case, so that this parameter can be factored out.

Quote:

If the LLR (Loop Length Ratio) of a cylinder is noticeably high and c) the switching time variations of the corresponding PD (Partial Discharge) element are noticeably high, what would you do next?

Okay, expand the PD (presumably a component), set the NW/stopper to the removal position, check the compression = everything is OK, swap the PD with another one --> the fault moves with it --> replace the PD, etc.

If these values are already significantly deviating from the norm, I think we're talking about a "clearly noticeable" issue, and not a "still subtle" problem that is just beginning, in relation to the initial question.

Metaphorically speaking, mine is like this:

The vehicle is missing air in the front left tire. There is a broken spring on the rear right side.
The ground clearance (measured at the wheel arches) is reduced by 5mm on both sides. Which side is the vehicle leaning towards, or is it considered acceptable simply because it happens to be standing straight?

Hello,

Quote:

If these values are already significantly deviating, I think we are talking about a "noticeably problematic" part, and not a "still inconspicuous" damage that is just beginning, referring to the initial question.

Yes, I see it similarly. The question is whether "unauffällig" means the car is still running without any issues, or whether it means "nothing can be detected."

Perhaps it would be a good idea to simply inquire how the term "questioner" is subtly defined.

Best regards, Rainer.

That's right.