I purchased a used Audi 2.0TFSI, registered in 2006, 4 weeks ago. After two weeks it began to misfire with the engine warning light flashing for a few seconds before going off. My local garage confirmed that the fault codes related to engine misfire and replaced the coil pack for number 1 cylinder as this was the indicated fault. It has since been misfiring again (the garage did warn me that the replacement may not be the cause). I have since researched the topic and found numerous references to carbon build-up causing this and more worryingly a tensioner pulley failure.

The cambelt was replaced at 53000 (6500 now on the clock), but I do not know if the pulleys were replaced at the same time.

All 4 coil packs were replaced 3 years ago and the spark plugs were renewed in January. The fault seems to be worst at 3000 rpm after the engine has warmed up. I assume that if carbon build up on the inlet valves was the problem then the misfire could occur at any time.

Do you have any suggestions as to how I should proceed? The car is booked in to my local garage again in two days time. All the work carried out so far has been covered by the warranty company.