A3 Diesel Power Loss Points to Failing Piston Rings

Recently had similar symptoms with my 2010 A4 2.0 TDI. The engine knocking and power loss turned out to be more complex than initially suspected. My original repair for a timing belt led to a chain of issues because it wasnt done correctly. The poor timing belt installation caused the camshaft timing to be slightly off, which eventually damaged the intake manifold and created serious compression problems. The symptoms matched yours, poor fuel economy, significant power loss, and warning lights. This required a complete top-end rebuild including new head gasket installation since the initial misalignment caused valve damage. It was a major repair that kept the car in the shop for over a week. The damage to the piston rings was evident once they opened up the engine. A proper diagnostic is crucial here, while your symptoms suggest piston ring wear, it could be related to previous repair work that wasnt done correctly. Would strongly suggest finding a certified specialist who can perform a compression test and leak-down test before proceeding with any repairs. The severity of this type of issue means it needs immediate attention to prevent additional engine damage. In my case, waiting made the problem significantly worse and more extensive.

Thanks for sharing those details. The camshaft timing issue you mentioned got my attention since I dealt with something eerily similar on my A3 last year. It started with the same symptoms, weak engine, poor fuel consumption, warning lights. My case turned out to be a combination of bad spark plugs and a timing issue that developed from a poorly done previous service. Did the complete rebuild solve all your problems? Just curious about the final cost of your repair and if you noticed any other issues pop up afterward. This kind of insight really helps when budgeting for these major repairs. The crankshaft position sensor also gave me trouble during the whole ordeal, so might be worth checking that too.

After getting the top-end rebuild completed, every issue was fully resolved. The cylinder pressure fluctuation that was causing the poor performance completely disappeared. Since the timing belt repair was originally done incorrectly at their shop, they covered the entire repair cost including the head gasket replacement, making it 0 Euro out of pocket for me. The fuel consumption returned to normal and the engine regained its full power. The fuel injectors were also inspected during the repair and cleaned as a precautionary measure. No new problems have emerged in the months since the repair was completed. A professional compression test confirmed everything is now working as it should. While the crankshaft position sensor you mentioned can certainly cause similar symptoms, in my case the root cause was definitely the botched timing belt installation that led to the valve timing issues. Getting the repair done under warranty was crucial since a full top-end rebuild with parts and labor typically runs several thousand Euro. Always worth checking if previous repair work is covered when issues arise from poor workmanship.

I finally bit the bullet and took my A3 to a different mechanic last week. The diagnostic tests revealed exactly what we suspected, the previous repair had caused a chain reaction of problems. The turbocharger was underperforming due to incorrect timing, and the piston rings showed significant wear from running with poor compression. The new shop did a thorough job documenting everything. They found metal shavings in the oil pan, which explained the engine knocking I was hearing. The full repair included replacing the piston rings, fixing the timing issues, and rebuilding the top end of the engine. They also replaced the crankshaft position sensor since it was showing signs of failure. Total cost came to 3200 Euro, but they knocked off 500 Euro since I brought proof of the previous shops faulty work. The car has been running like new for the past few days, no more power loss, fuel consumption is back to normal, and that annoying engine knock is gone. Pro tip for anyone facing similar issues: document everything and get a second opinion. The extra diagnostic fee is worth it to avoid further damage from poor repairs.