A6 2.5 TDI No Power: Common Problems & Fixes

Hello!

I'm experiencing a significant loss of power in my Audi A6 4B 2.5 TDI.
The mass airflow sensor (MAF) values are very low, as is the boost pressure. The MAF sensor has already been replaced, but there has been no change.

Lt. dem liegt die vermutung bei einem def. Cat.

Is there a way to use VCDS to check if the catalytic converter is actually defective?

Hello,

Looking inside the KAT (catalytic converter) is the only thing that helps. Are you sure the turbocharger is being controlled correctly?
Keyword: Vacuum sleeving.

Best regards, Rainer.

Yes, the vacuum pressure is correct, and the VTG (Variable Turbine Geometry) adjustment is working properly.

There's no rattling sound when you tap the KAT either.
NW looks good too.

Are you sure the pressure sensor itself is intact? Test it during startup to see if it actually engages. And when you stop, check if it retracts. }

I tested the pressure vessel with a vacuum pump, and there was no pressure loss.

Does it also work under vacuum?
"Previously, the plastic hoses located above the splash guard, where the hose leading to the brake booster connects, were leaking."
Just try taking it apart and, if you're a smoker, try blowing a little smoke into it and see what happens.

I replaced the catalytic converter, and now it's running wonderfully again.

I'm going to cut off the catalytic converter and post a picture if anyone is interested.

Best,
Chris

Yes, please.

Regards,
A.

Attached are the photos .

It just looks really messy.

Air mass okay, and no leaks in the charge air system? Is the software original?

Best regards, Rainer.

The vehicle had previously been tested on a dynamometer, and it was only producing 90 horsepower at the wheels.

AFB 150 hp.

According to the customer, something was modified on the software, resulting in approximately 180 horsepower, similar to the AKE.

The vehicle has been running perfectly since the catalytic converter was replaced and has full power.

Best, Chris.

And does it leave a trail of smoke like a steam locomotive when running at full speed?

To be honest, I wouldn't be surprised if this is a consequence of a failed attempt at "boundary limitation through air mass manipulation"...

Best regards, Rainer.

I'd like to try troubleshooting here as well.
It's only a matter of time before the "new" one looks like that again.

Is it just loose soot that can be removed by scraping, or is it a really hardened mass?

The soot can be scraped off; it's not baked on!

I no longer have the car, I have no idea who did the tuning, and I couldn't detect any excessive smoke during the test drive, it seemed perfectly normal.

Best,
Chris