Faulty Turbo, Mass Air Flow or Oxygen Sensor?

Hi!

"I'm experiencing a problem with my Audi A6 2.5 TDI AKE, manufactured in 2000 and with 220,000 km (approximately 137,000 miles) on the odometer, that I haven't been able to pinpoint yet..."

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

"Here's a fact:"

When accelerating from a standstill, there's a whistling sound coming from the turbocharger starting at around 2600 RPM, which is noticeable as a slight dip in engine speed.
It's like I briefly ease off the accelerator and then immediately press it down again to full throttle.

Even when the car is stationary, this can be noticed by slowly pressing the accelerator pedal and observing that the engine speed approaches the 2600 RPM mark.
Then this whistling sound comes back, and the engine suddenly revs up to 3400 RPM.

I've already checked the mass airflow sensor (MAF) using VAG-COM, and it's within the normal tolerance range when the engine is idling.

The intake manifold is slightly oily, and the EGR valve is not working.


Thank you.

We need full diagnostic logs. Your information isn't helpful. If the EGR is completely closed but the target and actual air mass readings are the same, something is wrong. The actual air mass should be higher at idle.

Hi!

I will upload the logs later today.

To rule out a problem with the LMM (likely referring to a mass airflow sensor), I built a diode replacement yesterday.
Under full load, this product delivers a maximum of (1000 mg/serving), while under normal conditions, it provides 900-950.
Previously, this was below the target range: Target: 250 mg/dL, Actual: 450 mg/dL.

Despite all of that, the problem remains.
Therefore, the topic of Large Language Models is now closed.

Greetings.