Audi TT Misfire Symptoms Point to Common Fixes

I dealt with very similar symptoms on my 2005 Audi A4 2.0T. Having some experience with engine performance issues, these symptoms immediately pointed to potential combustion misfire problems. The check engine light was constantly illuminated in my case. After initial diagnosis, it turned out to be a faulty fuel injector causing cylinder misfire and poor throttle response. The workshop found the injection valve was not atomizing fuel properly, leading to incomplete combustion. The repair involved: Complete diagnostic scan, Removal and testing of all injectors, Replacement of the defective injector, System cleaning, Final testing Total cost came to 515 Euro for parts and labor. The difference after repair was night and day, smooth acceleration, proper power delivery, and no more check engine light. Could you share some additional details about your TT: Engine size and type, Current mileage, When was the last fuel system service, Any recent maintenance performed, Does the problem occur more when the engine is cold or warm This information would help determine if your issue matches what I experienced, though the symptoms strongly suggest injector-related problems.

Last service was performed at 109756 KM with standard maintenance tasks completed. After investigating further, it looks like my ignition coils could be the culprit. When checking the error codes, I got P0301 and P0303 indicating cylinder misfire in cylinders 1 and 3. The engine misfiring is most noticeable when cold and seems to smooth out somewhat after warming up. I checked the spark plugs and they look pretty worn. Going to start by replacing all ignition coils and spark plugs since they are likely original to the car. The parts will cost around 280 Euro total. Has anyone else found this resolved similar symptoms? Want to confirm before ordering parts.

Having gone through almost identical issues with my A4, replacing the ignition coils and spark plugs sounds like the right approach based on those error codes. The symptoms you describe, especially the cold-start misfiring that improves when warm, perfectly match what can happen with deteriorated coils and plugs. When I first suspected fuel injectors in my case, I actually ended up replacing the coils and plugs first. This fixed about 80% of my issues, and only then did I discover one bad injector was causing the remaining problems. The check engine light finally cleared completely after addressing both. A few tips from my experience: Replace all coils and plugs at once since they age similarly, Make sure to use OEM or high-quality aftermarket parts, Check the coil connector wiring while you have them out, Clear the engine codes after replacement 280 Euro for a complete set sounds about right. Its much more cost-effective than trying one cylinder at a time, since rough idle and engine misfiring often cascade between cylinders when multiple coils are weak. The improvement in throttle response and elimination of the combustion misfire symptoms should be immediate if this is indeed the root cause.

Thanks for sharing your experience with the fuel injector issue. My engine is a 1.8T with about 180000 KM. The engine misfiring definitely seems worse during cold starts, which matches what you mentioned about ignition coils. I went ahead and ordered a full set of spark plugs and ignition coils for 280 Euro. The check engine light codes showing cylinder misfire in cylinders 1 and 3 make me confident this is the right path. The last maintenance was just standard service items at 109756 KM with no major repairs. Will install everything this weekend and report back on whether it resolves the rough running and power delivery issues. Really hoping this takes care of the problem since the symptoms align so closely with what others have experienced. If the engine misfiring continues after replacing these parts, I may need to investigate the fuel injectors like in your case. Good point about checking the coil wiring while everything is apart. Will definitely inspect all the connections during the repair. Appreciate the detailed information about your repair process, it helped confirm I am on the right track.