Audi A6 TDI Stuttering: VP44 Replacement Not a Fix?

Hello,

To begin, I would like to briefly introduce myself.
I am 34 years old, I studied industrial economics, and I drive a fourth-generation Golf with a 2.5 TDI BDG engine, which currently has 275,000 kilometers on the odometer.

Regarding my issue:
About a month ago, my car suddenly started making a loud knocking noise. I had to stop and have it towed home.
Diagnosis: Faulty fuel injection pump. Error codes: "00550 Injection time control valve - Control difference - intermittent" and "00550 Injection time control valve - Signal error - intermittent".

A newly refurbished fuel injection pump was ordered, coded, installed, and dynamically adjusted. Afterward, the car ran "rough" and emitted smoke in the partial load range between 1500 and 2000 RPM.
At full load, there is no smoke, and the performance is relatively normal.

Okay, here's the translation:

"Then I removed all the injectors and had them cleaned. One of them was faulty. I repaired it, reassembled everything, but the engine still runs poorly, with no improvement. Of course, I also checked the camshafts, and they look fine!"

Now I'm at the point where I think the new ESP isn't working correctly. I'm going to remove it again and send it back to the company for inspection.

I'll keep you updated...

Has anyone ever experienced a similar problem? I haven't found anything comparable in the search results.

Hi,

Autoscan?

Please log the target value and the actual value from the start of the injection process, specifically in the area where it's not working correctly, and also beyond that point.

Best regards, Rainer.

Hi, do you happen to know which channels are available in the VCDS?
Alternatively, I have autocom and autodia (carport).

Greetings.

Which channel do you see when you cycle through them, and how would I know if you were doing an automatic scan?

Guess measurement block 4 in the engine control unit...
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

Best regards, Rainer.

So hab jetzt soll/ist vom Spritzbeginn geloggt. Wenn ich im Teillastbereich bei besagter Drehzahl fahre und der Motor stottert und raucht habe ich eine extreme Abweichung, ein Delta von ca 8°! Bei Volllast wo er ja auch gut geht so gut wie keine Abweichung. Was heißt das jetzt? ESP defect?
I'll submit the log tomorrow.

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

"LG" is an abbreviation for "Liebe Grüße," which means "Best regards" or "Best wishes" in English.

Good morning, here's the log...

Is the timing belt tension correct? Strangely, the values are okay at higher RPMs...

Do you mean the small or the large timing belt?
I suppose so...

Check everything that drives the ESP system itself to see if anything is loose or if a pulley or guide roller is stuck.

Best regards, Rainer.

Okay, I will check all the timing marks on Saturday and see if anything is loose. The timing belt is 4 years old, and I've driven 70,000 km since it was replaced (just for your information).
Report back later.

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

"LG" is an abbreviation for "Liebe Grüße," which means "Best regards" or "Best wishes" in English.

Good morning.

Slightly delayed, but there was no other way to do it given the timing.

Yesterday, we disconnected the motor: we positioned the motor at top dead center (TDC), inserted the mandrel from below, and disconnected the ESP (electrical spark plug) from the top.
After that, I removed the vacuum pump and took off the rear cover of the camshaft on the other side. The rulers/gauges wouldn't fit inside... I removed the camshaft gears, inserted the ruler/gauge, and reattached the camshaft gears.
Everything is assembled, but the car is still running just as poorly as before. I noticed that the gear (attached with 3 Allen screws) for the dynamic ESP adjustment seems to wobble slightly when the engine is running. However, the camshaft gear does not.
Could that be a possible cause?

We will also be checking the tension of the timing belt in the next few days; unfortunately, it was too late to do so yesterday.

What I also noticed is that, while it runs smoothly at higher RPMs, it doesn't seem to be delivering its full power; something is missing.

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

"LG" is an abbreviation for "Liebe Grüße," which means "Best regards" or "Best wishes" in English.

Hi,

Then I would start by investigating the mechanical issue. Are the ESP brackets in good condition?


Best regards.
Adrian.

In the coming days, I will fix this imbalance in the gear and check the tension of the long timing belt.
I'll get back to you.

Best regards.

P.S. The ESP brackets are in good condition.

Hello.

"My V6 also exhibits a somewhat wavy acceleration when using partial throttle. You can also notice it when coasting. There were absolutely no error codes in the diagnostic memory. The injectors look great. After a long search, I identified the mass airflow sensor. It indirectly determines the fuel injection amount."
Okay, please provide the German text you would like me to translate into English. I will provide only the translation.

The LMM reaches a value of 940 in third gear.
I also tried one from a different BDG (presumably a German organization), just to see, but it runs just as poorly...

I will remove these "burrs" from the camshaft sprocket in the coming days and check the timing belt.

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

"Lg" is a German abbreviation that stands for "Liebe Grüße," which means "Best regards" or "Warm greetings" in English.

Update:

Front panel removed and valve cover taken off.
The timing belt seems to be a little too loose, so it will be tightened.

We also noticed that some of the hydraulic lifters are very loose, so we're replacing them all. I'll report back again and hope that it runs correctly this time.

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

"LG" is an abbreviation for "Liebe Grüße," which means "Best regards" or "Best wishes" in English.