ZR Seal Replacement: Performance Loss Troubleshooting

Hello,

I hope you can help me with my problem.
After a timing belt replacement during the 90,000 km service (at a specialized workshop!), I unfortunately noticed while driving on the highway that the engine lacked power above 100 km/h, and the maximum speed was limited to 180 km/h. Normally, it should be around 195 km/h.

A primary suspect was immediately identified: the mass airflow sensor (MAF).
This part was replaced (Intermotor 19600), which is a replacement for VAG 06A 906 461. The original part is Bosch F 00C 2G2 056. Unfortunately, there was no improvement.

A measurement run yielded the following results:

Idle:
Target and actual values in measurement blocks 0, 1, 2, 3, and 4 = completely normal.

Full load:
The target values for the engine control unit in measurement blocks 0, 4, 8, 10, and 11 are being determined correctly, however, the actual values are significantly different from the target values due to insufficient air mass (e.g., target: 850 mg/H, actual: 540 mg/H). The values for boost pressure and intercooler temperature, however, are correct.

Now, the following question arises:
Does the motor controller need to go through a learning phase with the new mass airflow sensor, or should an improvement be noticeable immediately?
Or, if the LMM is not the cause, what else could be causing the missing LM?

I have already read the relevant technical articles on root cause analysis, and most of the potential error sources have been systematically checked and ruled out. During a visual inspection of the intake manifold/cooling system, I could not detect any damage or leaks.

Does anyone have any other suggestions on where I should go next or where I can look?

Hi.

spuernase wrote:

A measurement run yielded the following results: Idle: Target and actual values in measurement blocks 0, 1, 2, 3, and 4 = completely normal.

Idle time is not relevant to your problem.

spuernase wrote:

Full load: The target values for the engine control unit in measurement blocks 0, 4, 8, 10, and 11 are being determined correctly, however, the actual values are significantly different from the target values due to insufficient air mass (e.g., target: 850 mg/H, actual: 540 mg/H). The values for boost pressure and intercooler temperature, however, are correct. Now, the following question arises: Does the motor controller need to go through a learning phase with the new mass airflow sensor, or should an improvement be noticeable immediately? Or, if the LMM is not the cause, what else could be causing the missing LM?

No, there is no learning phase. Either the wrong LMM (lambda sensor) was installed, or a defective one, or the engine is not drawing in enough air.
Possible causes: Blockage in the intake system/air filter housing (e.g., cleaning cloths?) or in the exhaust system (catalytic converter).
NW might also be misaligned, but with such drastic changes, the valves on the piston would probably have already popped open.

Is the error memory empty?

Best regards, Rainer.

Unfortunately, the diagnostic scan revealed nothing - no errors were stored.
Die Ansaugstrecke habe ich schon komplett geprüft. Everything's fine.
The exhaust system was only subject to a visual inspection. However, no abnormalities were found.
I'm not entirely sure if the LMM from Intermotor is correct.
However, the specified VAG number matches my vehicle identification number (VIN).
So, it should fit. If the northwest corner had been adjusted even slightly,
It shouldn't just affect one specific aspect, but rather be noticeable throughout the entire running behavior of the engine.
Irregular running, for example?

spuernase wrote:

... If the northwest direction had been adjusted even slightly, It shouldn't just affect one specific aspect, but rather be noticeable throughout the entire running behavior of the engine. Unrunder Lauf z. B.?

Not necessarily, but a lack of performance would definitely be a mistake .

Okay, I'm ready. Please provide the German text you want me to translate.

Bertil wrote:

Not necessarily, but a lack of performance would definitely be a mistake . /viewtopic.php?t=5408

Okay, then I will bring this issue up with the technicians at the workshop. Thank you for the information.

Hi,

Quote:

However, the actual values are significantly different from the target values due to insufficient air mass (e.g., TARGET 850 mg/H - ACTUAL 540 mg/H).

If the measurement is correct, the amount of fuel injected should decrease significantly. The fact that the problem appeared after the timing chain replacement suggests that there might be an error. However, according to Murphy's Law, it's probably just a coincidence.

Best regards, Rainer.

Rainer K. wrote:

Hi, if measured correctly, the amount of fuel injected should decrease significantly with this. The fact that the problem appeared after the timing chain replacement suggests that there was a mistake made.

Wenn ich mich recht erinnere (genauen Wert habe ich leider nicht) ist das tatsächlich so gewesen. Macht ja auch Sinn, denn die Steuerung muss ja bei einem so geringen LM-Wert davon ausgehen, dass nicht mehr gebraucht wird. Or what?

I hope I can do another test drive this week with a VAG tester and logs recorded. Maybe one of you could then take a look at the logs. Because the first test drive was unfortunately with a VAG tester that only allowed reading of current values. Of course, that could also lead to reading errors.

What I haven't quite understood yet is how an adjustment of the needle valve (NW) can affect the injection timing (LM). I can understand the part about the injection quantity and injection start (as explained in the technical article "Adjusting valve timing and PDE").

spuernase wrote:

What I haven't quite understood yet is how a northwest shift can influence the LM.

Of course, the valve timing has a certain influence on the cylinder filling = mass airflow rate.
However, the possible adjustment range in the northwest direction before the valve assembly is, in my opinion, certainly not large enough to cause a drop in air mass from approximately 850 to 540 mg.

ulf wrote:

But the possible adjustment range in the NW direction before the piston-valve assembly is, in my opinion, definitely not so large that the air mass drops from approximately 850 to 540 mg.

Okay, I'm also considering another possibility: that the replacement mass airflow sensor (MAF) isn't the right one. If everything goes according to plan, I should be able to obtain a 100% correct and functional MAF sensor from a comparable engine soon. This will hopefully allow me to definitively rule out the MAF sensor as the source of the problem.

Thank you in advance to all those who are helping. I will let you know how things develop.

spuernase wrote:

Thank you in advance to all those who are helping. I will let you know how things develop.

"This weekend, I was able to conduct a test run and log some data using VAGCom. Maybe one of you will take a look at the logs and share your opinion. At first glance, it's clear that there isn't enough air mass being measured under full load. Unfortunately, I haven't yet been able to get my hands on a 100% functional and correct mass airflow sensor (MAF) to test."

Here is the link to the log table (Excel) http://www.webwaechter.de/golf/log_04.xls.

Hi,

Please review how these logs should be conducted properly.

Most importantly, the system should include at least one full-load acceleration profile ranging from 1500 to 4000 RPM, and ideally, this should be achieved in the highest possible gear. Unfortunately, your system is missing this.

Sure, I can do that. Please provide the German text you would like me to translate. I will translate it into English, using MWB 11 (3-8-11), and present the translation as a diagram.

Regards,
Guste.

Thank you for your comment. I will take care of it.