Seat Arona engine knocking power loss and smoke

Reduced engine power, jerking, and smoke sounds rough. I had similar issues with my Arona. Have you checked for error codes? The error memory stored some detonation issues for me. It might be piston slap, or pre-ignition. I would check the combustion chamber.

Cheers for the quick reply. There's an error code stored, but I haven't got the details handy. Detonation issues and piston slap sound scary. How did you pinpoint the combustion chamber? What exactly was happening?

The error code pointed towards misfires and timing issues. The garage used a borescope to inspect the combustion chambers. Carbon deposits had built up causing pre-ignition and detonation, so the fuel was igniting at the wrong time, causing the engine knock. Given your symptoms, it sounds similar. I'd get a mechanic to check it out properly to catch it early.

You were spot on. The workshop scoped the combustion chambers and found major carbon buildup. A chemical clean fixed it, and it's running great. Cost 425€, but worth it. No more jerking, the power's back, and no smoke. Thanks for the help.