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Thanks for the tip. I will post the Excel file tonight.

Rainer.

I hope this is clearer.
/viewtopic.php?p=113721#113721

Do you have any idea what this could be?

Rainer.

Hello,
Maybe I've found the cause of the 575 error.
"I logged the data again, this time including the intake air temperature (07). At an ambient air temperature of 30 degrees Celsius, the intake air temperature is normal after starting the engine, but it quickly rises to 88-92 degrees and remains constant above 88 degrees, regardless of whether the engine is idling or running with 2 bar of boost. Even after the limp-home mode starts, it stays consistently around 90 degrees. I'm going to replace the sensor. What surprises me is that no error code (intake air temperature sensor) is being stored."

Rainer.

Hello,
"After trying to address all the suggestions here during my limited free time and still not finding the problem, I hopefully had success with the repair manual. It stated that you should take a test drive with the N75 disconnected. If the boost pressure is too low (which it was), then either there's a leak in the charge air system (I've already tried to find a leak 10 times), the turbocharger is faulty (which is what I was most afraid of), or the linkage for the pressure sensor is misadjusted."
So, I adjusted the rod according to the repair manual.
"Now it feels much better overall, and from what I can see as a non-expert, the boost pressure seems to be back within range. However, the air mass reading is making me suspicious."
I would like to ask you to please take a look at the log and let me know if everything is okay now, especially with the "turbo" feature, or if I still have another issue.
Thank you in advance.

Best regards, Kaindl.

Log 003-008-011:
Okay, I'm ready. Please provide the German text you want me to translate into English. Just paste it here, and I will give you the translation.

Hi,

Your log in third gear only provides ten data points between 1500 and 4000 RPM. A log in fourth or even fifth gear would be better, as it would offer a finer resolution, provided this is easily possible in your area (e.g., on the highway).

Here's what you can also clearly see: Your air mass begins to drop at 3500 RPM, which indicates an aging mass airflow sensor (MAF). However, since the soot limit is still above the torque limit, it's not yet causing a noticeable loss of power.

Over time, your DPF (Diesel Particulate Filter) will continue to age, which will eventually cause the soot limit to drop below the regeneration threshold, leading to a loss of performance. Therefore, it will need to be replaced sooner or later anyway.

Everything else seems unremarkable to me.

Are you saying that you only solved the problem by adjusting the factory-set tension rod after more than ten years? If so, then I think this would be the first time we've encountered a "aged" tension rod setting. Or perhaps the previous owner messed with it.

Regards,
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It refers to a sudden and strong gust of wind.

A burnout on the highway would be possible... Starting in fifth gear from a standstill, flooring it and accelerating as quickly as possible – is that what you mean?
Are there any other possible causes for the decreasing air mass besides the mass airflow sensor (MAF)?
Just to recap the background: my father was the only previous owner of the Audi. Shortly before I got the car, the power loss first became noticeable while it was literally on its roof (due to an accident). My father then unfortunately took it to ATU, who convinced him to replace the mass airflow sensor (MAF). So, this MAF is only about 1.5 years old. If the problem is related to that, ATU will be getting a strongly worded letter!
After the error wasn't fixed, I took it to a mechanic who used to work on VAG vehicles. He replaced the pressure sensor and the N75 valve. However, the error still persisted, so I started investigating myself.
The pressure sensor was probably misconfigured during installation.
So, no outdated rod settings and ATU-LMM .
Thank you in advance for the analysis of the log! I'm glad that at least now everything works properly with the charger again .
Best regards, Kaindl.

I spent over two years searching for the same problem (Audi 80 1Z, year 1994, version with mass airflow sensor, power loss at 160 km/h or when driving in the Kassel Hills with a trailer, error code 00575, intake manifold pressure, control difference).
The search for repair manuals was unsuccessful. The turbocharger boost pressure is okay, and the hoses are fine. Replacing the solenoid valve didn't solve the problem. I haven't implemented the expensive suggestions from the workshop, such as replacing the turbocharger or the ESP system.
Adjusting the control rod on the loader also did not provide a real solution.
The ultimate cause was an oil-contaminated pressure line running from the intercooler to the pressure sensor in the engine control unit. When disconnected at the control unit, it initially released oil under pressure, followed by air. Everything has been fine for over 100,000 kilometers since then.
The vacuum sensor for the turbocharger pressure control also tends to get oily. If it's otherwise mechanically okay, just try emptying it.

Perhaps this will help you. In any case, it won't take much time and doesn't cost anything else.

Best regards.
Herbert.

Thanks for the tip, but my turbo is working again as it should; the problem is that the air mass starts to drop off at a certain RPM. I already recorded a log while driving on the highway this week, and I just need to process it in Excel before posting it here.
So, this tip doesn't help me anymore, but maybe it will help someone else .
Best regards, Kaindl.

Okay, I've set up the log now.
Beschleunigung auf der AB 4.+5. Full throttle.
Perhaps someone can provide more details about this.
Thank you in advance.

Best regards, Kaindl.

Log 003-008-011:
Okay, I'm ready. Please provide the German text you want me to translate into English.

Hello Kaindl,

In the log, I don't see any performance degradation, but you already fixed that issue by changing the bars.

The only noticeable issue is the mass airflow sensor (MAF), which fails to reach its target values even at 3000 RPM. Either the MAF sensor itself is faulty, or there's a leak (likely a vacuum leak) between the MAF sensor and the turbocharger. The latter is often difficult to detect because no oil is being forced out. However, it's only a short section of tubing, so it can be quickly removed for inspection.

Regards,
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It refers to a sudden and strong gust of wind.

There certainly isn't another possibility, is there?
Then I'll take a good look at the system and, if there's no leak, I'll tell ATU to shove their mass airflow sensor (MAF) where the sun doesn't shine! But of course, I need to be absolutely sure that it's the MAF causing the problem .
Best regards, Kaindl.

Hello,
I got a replacement Mass Air Flow sensor (MAF) from ATU under warranty on Wednesday, and today I took it for another test drive on the highway.
To me, it looks like the problem hasn't been fixed. My LM values are dropping again below 3000 RPM.
I would be grateful if someone could review the log again .
And if it still doesn't fit, what is the easiest way to find the leak between the mass airflow sensor (MAF) and the air intake manifold?
Thank you in advance.
Best regards, Kaindl.

Log: (1. Teil 4. Gang Vollgas, 2. Teil 5. (Go full throttle)
Okay, I'm ready. Please provide the German text you want me to translate into English.

It's actually normal for the airflow to decrease at high engine speeds. The valve opening times become shorter, and the mass of air per stroke has to pass through the pipes in a shorter amount of time. This results in increased flow resistance.

Er geht bis zum Ende des Log bei 4500 U/min nicht in die Rauchgrenze. Okay, then. / That's fine. / So it's okay.
"Boost pressure is also correct."

Everything is fine.

Hey everyone,

I spent a lot of time on the highway this weekend and drove at full speed for a very long time.
During this time, the engine went into emergency mode once and displayed the attached error code.
The boost pressure value remained at zero, and the control system was also frozen. I couldn't clear the error code; it immediately reappeared. I turned off the engine, disconnected the intake manifold pressure sensor connector, wiggled the connector, reconnected everything, cleared all the errors, and restarted the engine.

Everything worked without any problems, and the system itself functioned perfectly. I then drove another 500 km quickly and didn't experience any more issues. I had a similar problem many years ago, but back then I didn't have VCDS; after restarting the engine, everything was fine again, and there were no further issues.

The boost pressure is perfectly fine, and it's increasing smoothly as expected.

What do you think? Should I replace the MAP sensor just to be sure? Wouldn't a leak cause problems more consistently?
The N75 is about 2 years old, but all the other sensors are from 1998 and have over 300,000 kilometers (approximately 186,000 miles) on them.

I partially replaced some of the vacuum hoses about a year ago, but not all of them, including the ones that go to the wastegate valve.

As I said, the car has been running perfectly normally since then, just like always. However, I don't want to experience the same problem again on my next long trip, especially without VCDS.
However, it's not really reproducible; I've taken my car on countless trips, and this is only the second time it's ever caused any problems.


It's an ALH engine with approximately 330,000 kilometers (about 205,000 miles) on it. Everything except the N75 valve is original from 1998.

Control unit part number: 038 906 018 AR.
Component and/or version: 1.9L R4 EDC G00SG 1820.
Encoding: 00002
Company number: WSC 06325
VCID: 66C7DA0302E9032E0EF-4AE6
'One error found:'

00575 - Intake manifold pressure.
17-00 - Rule difference.

Readiness: Not available.

Due to saltwater and constant load (resulting in little movement of the variable geometry turbine), it can become difficult to move due to rust, even though the adjustment mechanism in the turbocharger is functioning correctly.
Of course, at this mileage, the latter issue (the VTG sticking in the charger housing) is almost to be expected. However, it wouldn't hurt to apply copper-based thermal paste once to the following areas:
- at the VTG adjustment lever, where it connects to the turbocharger housing.
- at the joint that connects the adjustment rod of the vacuum actuator to the adjustment lever.
The paste dries out, but a protective layer of copper dust forms on the surface.

Please do not use any oils or other fats, as they tend to carbonize very quickly once the loader heats up, and this will only make things worse!

Best regards, Rainer.

Quote:

It's an ALH engine with approximately 330,000 kilometers on the odometer now.

The cause is likely a faulty charging unit housing. It then jams under full load. The mileage is not unusual for this issue.

Note: The ALH engine may not be able to handle sustained full throttle operation reliably, especially at higher mileage. If you want to enjoy it for longer, avoid prolonged full-throttle driving – otherwise, it can easily lead to piston failure.