Audi A2 Diesel Power Loss Points to Cylinder Issues

Had exactly the same symptoms on my 2001 Audi A3 diesel. As someone who regularly does basic maintenance like oil changes and brake pad replacements, I know my way around engines but still rely on professionals for complex issues. The symptoms you describe match my experience perfectly, higher fuel consumption, power loss, and check engine light. Initially thought it was the head gasket too, but it turned out the intake manifold was damaged due to a previous repair where debris from a broken fuel injector hadnt been completely cleaned out. Since the fuel injector damage was covered under warranty from the previous repair, fixing the intake manifold issue cost nothing. The workshop also checked the piston rings and spark plugs while they were at it, all clear there. To help diagnose your specific case, could you share: Current mileage, When was the last fuel injector service done, Any recent repairs or maintenance, Are you noticing any unusual exhaust smoke, Any rough idling or strange noises These details would help determine if your issue matches what I experienced or if its something different.

Thanks for the info about the intake manifold issue. My current mileage is 160863 KM and I should add that I notice black smoke from the exhaust when accelerating hard. The last fuel injector service was about 2 years ago but the rough idle started recently. No unusual engine noises though. The head gasket seems fine as there is no coolant loss or white smoke. Could damaged piston rings be causing these symptoms instead? Just looking to narrow down possibilities before taking it to the shop.

Having dealt with similar issues on my A3, black smoke during acceleration combined with rough idle often points to fuel injection problems rather than piston rings. While damaged piston rings can cause similar symptoms, the combination of increased fuel consumption and black smoke typically suggests the fuel injectors arent atomizing diesel properly. After my intake manifold was repaired, we discovered two fuel injectors were partially clogged, causing uneven fuel distribution. This matches your symptoms, especially the black smoke, which usually means too much fuel is being dumped into the cylinders without proper atomization. Since your last fuel injector service was 2 years ago, I suggest getting them tested before exploring more invasive repairs like piston rings. The diagnostic scan from my experience showed multiple misfires across different cylinders, which initially made it seem like a compression issue, but was actually due to poor fuel delivery. The rough idle you mentioned recently starting is another classic sign of injector problems. My idle smoothed out completely after the injector replacement. Consider getting: Fuel injector diagnostic test, Compression test to rule out piston rings, Fuel pressure test, Complete system scan These tests helped identify the root cause in my case without unnecessary parts replacement.

Thanks for all the detailed feedback. After what you mentioned about the fuel injectors, I just remembered an important detail, the car occasionally has a slight engine knocking sound when cold, which goes away after warming up. This, combined with the black smoke and rough idle, makes me think you might be right about the injectors rather than the head gasket or piston rings. I will book it in for those diagnostic tests you suggested, focusing first on the fuel system. The turbocharger seems fine since there is no loss of boost pressure, so that is probably not related. Will definitely get them to check the intake manifold too, given your experience with debris causing issues there. The crankshaft and timing seem okay since there are no unusual noises or vibrations at higher RPMs. Hopefully its just the injectors needing cleaning or replacement rather than anything more serious. Will update once I get the diagnostic results back.