A3 TDI PD: Vibration Problems & Solutions

Hello everyone!

I drive an A3 Ambition TDI with 96 kW, engine code ASZ. It has 12,000 km on the clock and was manufactured in 04/2001. I'm very happy with my car; it's fast and averages just under 6 liters per 100 km. So far, so good. However, I've been experiencing a problem for the past few days. When the engine hasn't fully warmed up, it seems to be surging. It's most noticeable at idle. The engine runs normally, and there's no noticeable idle fluctuation, but the whole car starts to shake – not a vibration, but more like people are trying to tip the car over, although that's an exaggeration. The strange thing is that once the engine reaches operating temperature, after about 10 minutes of driving, this effect disappears and everything is normal.
I would appreciate it if someone could help me.
This forum is truly excellent and full of knowledgeable people, and it has certainly helped many. It could have helped me too when I still had my Golf III TDI (AFN) and was dealing with numerous problems.
Therefore, I switched to Audi, but it seems that not everything is as good as it appears.

Best regards, Norbert!

Hi.

What problems did you experience with the AFN Golf, and how were they resolved (or attempted to be resolved)?

(I would like to know what else might be in store for me ).

Hello,

Have you had the values of the idle speed control (engine control unit, measurement block 13) read out, and possibly the error memory?

@ulf: Zu den Probs mit meinem AFN Golf III. It was manufactured in May 1996.
At 35,000 km (approximately 22,000 miles), the timing belt was replaced, and the car ran smoothly until around 25,000 km (approximately 15,500 miles). From that point on, it started experiencing power loss, and the engine would occasionally go into limp mode. It turned out to be the turbocharger boost control valve. However, I was convinced that the engine wasn't running correctly from that point onward. At 45,000 km (approximately 28,000 miles), there was a noticeable drop in acceleration at 3,000 rpm, but it then returned to normal. This time, it was the mass airflow sensor. From 50,000 km (approximately 31,000 miles), there was no power in the lower RPM range, and the acceleration was similar to a well-maintained SDI Golf. The workshop checked everything thoroughly but found no errors. There were no error codes stored, and the workshop also confirmed that the variable turbine geometry (VTG) of the turbocharger was functioning correctly. All the hoses were also checked for leaks, but nothing was found. At that point, I gave up. It was a shame because the engine was otherwise very good and had low fuel consumption. I probably bought it a little too early, as mine was one of the first AFN engines in the Golf III.
Best regards, Norbert!

@Michael II:
I already took it to the workshop because of this issue, and as usual, they first checked the error memory, but it didn't show any errors. I'm not sure if they also read out the idle speed control value, but I'll ask about that next time.
Thank you for the information!

Best regards, Norbert!