TDI Power Loss A3: Troubleshooting & Solutions

Hello!

'I've been having problems with my A3 for a few weeks now. The car was manufactured in 04/01, the engine code is ASZ, and it only has 25,000 km (approximately 15,500 miles) on it. It used to impress me with its impressive performance, but for the past few weeks, that's all come to an end.'
The cart shows the following changes compared to its original condition:

1. It doesn't react quite as spontaneously to accelerator pedal movements anymore.
2. Acceleration dip between 2400 and 2800 RPM.
3. In this area, there is almost no more draft, even in the higher gears.
4. Top speed is no longer being reached.

The described symptoms are always present, but it seems like the car is getting slower.
Since the mechanics at my local workshop don't seem very knowledgeable about this issue, I would be very grateful for any suggestions regarding a possible cause, before they completely disassemble my car and I end up needing to seek debt counseling...

Best regards,
Norbert.
For the sake of completeness: I once had a faulty temperature sensor, which was stored in the error memory. At that time, the car also had less power, but the symptoms were different.

Hello A3Bert!

The search function is your friend. When it comes to the topic of performance loss, you'll find so many posts that you'll be overwhelmed!

But I don't want to be completely unhelpful, so here are some additional keywords for you:
- Have the LMM checked.
- Check (or have checked) the free movement of the VTG (variable track gauge) mechanism.
- Injection start control.

Given your significant performance issues, I suspect a problem with the VTG (Variable Turbine Geometry) adjustment. Please read Ulf's expert article on this topic.

Regards,
Alex.

First of all, thank you, Alex, for your quick response.

'I was at the workshop today, and they quickly checked the VTG (vaneless turbo geometry) of the turbocharger and found nothing wrong. The master mechanic said it couldn't be the problem. A test drive was scheduled for tomorrow due to time constraints. Then, he mentioned that he would definitely install a new mass airflow sensor (MAF) for me by tomorrow, as it's always a possibility (especially with recurring errors like mine), and it would be done at the same time.'
We can (at least for now ) skip the test drive. The car is running like new again. The lack of acceleration is gone, the power is back, and noticeable thrust now starts at 1500 RPM, previously around 1800 RPM; with the new mass airflow sensor, the 'catapult' effect is already noticeable.
Okay, now I can only hope that this lasts, that the LMM isn't too expensive, and that it lasts longer than the original one.

Best regards, Norbert!

Hello Norbert,

The LMM/HFM lasts longer if it is not exposed to oil mist (from a sports air filter) and dirt.
Air filter functioning properly?

Best regards, Rainer.

Hello Norbert,
The price of the LMM (likely a sensor or module) is 270 euros. The installation costs shouldn't be high, as it can be replaced in about 10 minutes.
Best regards, Alois.

Hello!

€270 is outrageous! Thanks for the information, Alex.
Okay, I can now test drive the new engine for a week, and then the workshop will submit a goodwill request. Let's see what I actually have to pay. I really let loose at the workshop today, venting my frustration about how constantly things break down on these TDI cars. When I think about my previous car, I get a bad feeling (a Golf 3 81kw TDI, manufactured in 1996, engine code AFN). I had to get rid of it because I would have become a social welfare case. I then took a test drive in a 96kw A3 and was completely thrilled. That engine just works best in the A3. Then, after I signed the contract, the salesperson made a crucial mistake by saying that the problems I had with my AFN Golf wouldn't occur with the ASZ A3. He got to hear about that today. Balance after 25,000 km: 2 times...
'Emergency mode (once a valve, the second time a temperature sensor), and now the mass airflow sensor. At this mileage, even my AFN Golf ran without any issues. The next problem, and I'll go crazy! However, one thing has to be said: the 96kW engine is a great combination with the A3. Unfortunately, I haven't been able to drive a Golf with this engine for comparison, only the Passat and the new A4, and in both cases, I was severely disappointed. Especially when driving the Passat, it's hard to believe that it's the same engine.'

Regards,
Norbert!