A3 1.9 TDI: Mysterious Engine Problem

I'm writing this email because I was planning to go on vacation with my car the day after tomorrow, but it looks like that's not going to happen anymore.

Thank you in advance to everyone who takes the time to look into my problem!

First, a brief introduction to the background:
My A3 TDI (manufactured in 09/99, 90 hp, 108,000 km, AGR) has lost a bit of power over the past year; instead of 210 km/h (according to the speedometer), it only reached 200 km/h (with difficulty) since last summer! Additionally, the acceleration in the mid to upper RPM range has decreased slightly, while there was no noticeable difference at lower RPMs. The idle speed has never been perfectly smooth since the beginning (slight hesitation at low RPMs), but it wasn't really alarming. Audi classified all of these problems as normal wear and tear.

This morning, however, I was shocked: I turned the key, the car started, and I immediately noticed that it was lacking a lot of power. On a flat road, it could only reach 120 km/h, and even uphill, it was only able to manage 70 km/h. The car takes forever to reach its operating speed, and the sound of the turbocharger spooling up is (perhaps subjectively) no longer audible. However, the engine runs normally at idle, and there are no unusual noises while driving. Also, no warning lights are illuminated, such as the 'engine control error' light. During my initial inspection of the engine compartment, I didn't notice any visible damage.
I'm quite desperate because I was supposed to visit my grandmother in Vienna the day after tomorrow, but unfortunately, that's no longer possible.
My last hope is that this problem can be resolved as quickly as it appeared.
Thank you in advance to all the helpful Santas – and Merry Christmas!

Maria.

Hello,

Your error description isn't very "clear," but it sounds a lot like a fallback program is running.
-> Read the error codes; otherwise, you'll be shooting in the dark.
Are there any other noticeable issues? Any starting problems, smoking, etc.?

Best regards, Rainer.

That sounds like a faulty catalytic converter, especially if there are no other symptoms present (like a faulty sensor or a limp-home mode).

'I experienced something similar with my AFN engine at around 95,000 km. However, I was still able to drive at least 160 km/h. But I must keep it a secret that a 45 horsepower Panda pushed me while accelerating.'

I know many people whose catalytic converters failed around 100,000 km. However, all of them had AFN engines. I'm not sure if this problem occurs more frequently with the 1Z engine.

Regards,

Manuel.

Hello,

Your error description isn't very 'clear,' but it sounds a lot like a fallback program is running.
-> Read the error codes; otherwise, you'll be shooting in the dark.
Are there any other noticeable issues? Any starting problems, smoking, etc.?

Greetings, Rainer

Thank you for your reply. However, that's not the emergency program; it drives differently, and it has appeared earlier for me before .
It's almost as if I now have a VW Beetle engine in my Audi! =-100 in 25 seconds, and it cuts out at 110 km/h. On hills, you have to be afraid of being overtaken by a tractor. And as I said, the car was parked in perfect condition in the evening, and the next morning, right from the first start, I received a 'wonderful' Christmas gift! Otherwise, nothing unusual - no smoking, no rumbling, no starting problems, and the engine sounds normal; it just takes a long time to reach the correct RPM. The only thing that seems to be missing is the characteristic sound of the turbine venting. The only thing I noticed in this context was that the car smelled quite strange from the exhaust when starting cold - but according to VAG, it's a 'completely normal' diesel smell!

Hi.

Now would be a good time to troubleshoot using VAGCOM.
Without the appropriate data, I can only speculate that either no more boost pressure is being generated, or that the mass airflow sensor is faulty.

If you had an LDA on board, or could at least temporarily connect one, we could potentially see further.

Otherwise, you might want to try replacing or cleaning the mass airflow sensor (MAF sensor) as a precaution.
And also check its electrical connections for loose connections, bent cables, and corrosion.