Bad Car Behavior: Mechanic Can't Find Issue

Hello everyone!

I've owned an Audi A4 (8E) with a 96KW TDI engine since February 2001. For about half a year, I've noticed a significant lack of power when starting, and a poor response even at higher RPMs. The engine also sometimes stutters briefly when cruising. It feels like the engine pauses for a couple of 'thinking' seconds when I suddenly accelerate. This symptom is particularly noticeable in high outdoor temperatures.

What I find particularly frustrating is that the Audi service center isn't taking the issue seriously and is pointing out that the diagnostic tool isn't showing any errors. This is my second TDI, and I also had a lot of problems and expenses with my previous one (a Passat, 81 kW), including a faulty turbocharger.

Of course, I've browsed through the posts and searched for similar bug reports, but I haven't found anything that really fits . Unfortunately, I also didn't understand much, because my technical knowledge is very limited, and many technical terms are used here. (How did I even pass the entrance test? Well, some physics knowledge must have stuck with me:-)) Maybe I just wanted to vent my frustration...

Best regards,
Andreas.

Hi Andreas,

Do you notice anything else?
Increased soot production or unusual noises?
Ölverbrauch? Water consumption?
Will the specified maximum speed be reached?

I once had a similar problem with my Golf, when the EGR valve got stuck and remained open all the time.

This valve is designed to deliberately release exhaust gases into the intake air under partial load, for temperature and exhaust quality reasons, and should close again under full load. If it doesn't close, you'll experience... poor acceleration... because exhaust gases are still being drawn into the intake.

There is a technical article about this AGR valve here.

/viewtopic.php?t=3095

Otherwise, a boost pressure gauge is always helpful for troubleshooting. It allows you to immediately see whether the boost pressure is being built up correctly or not, which can help you narrow down the source of the problem.

I'm assuming the A4 is in its standard configuration and hasn't been modified or tuned?

Greetings.
Thomas.

Possibly, this also applies here:

/viewtopic.php?t=3657

Hi,

If that were the case, it would almost be a major engine failure, considering the prices of the PD-E engines.

Greetings.
Thomas.