Audi Q8 Misfire Issues: Warning Signs and Fixes

I had a very similar issue with my Audi Q7 from just 2 years older than your Q8. Having some experience with various engine issues, I can share my troubleshooting journey. The symptoms you describe, rough idle, poor throttle response, and cylinder misfire, match exactly what I experienced. Initially, I also thought it might be spark plugs, but diagnostic testing revealed a faulty fuel injector that was causing irregular combustion misfire in one cylinder. The repair involved: Complete diagnostic scan, Fuel injector replacement, Fuel system cleaning, Testing under various load conditions Total cost was 515 Euro and the repair took about 4 hours. Since the fix, the engine runs perfectly smooth with no issues. Before jumping to conclusions, could you share: Current mileage on your Q8? Does the misfire occur more frequently when the engine is cold or warm? Have you noticed any fuel consumption changes? Any unusual exhaust smell? This information would help determine if your issue stems from the same root cause. Modern fuel injection systems are complex, and accurate diagnosis is crucial for proper repair.

My Q8 has 193849 KM and was last serviced 3 months ago. Since then, I have noticed the engine misfiring gets worse when the engine is warm, particularly during highway driving. Fuel consumption has increased by about 15%. The exhaust smells normal but there is a slight rattling sound during acceleration. The spark plugs were actually checked during the last service and were fine. Given this additional info, I am starting to suspect it might indeed be a fuel injector issue like you mentioned. Good to know about the repair costs, I will get it checked at the workshop this week.

Thanks for providing those details about your Q8. The symptoms you describe strengthen my initial suspicion about the fuel injector being the culprit. When I had mine replaced, I also noticed that telltale combination of rough idle and increased fuel consumption. The rattling during acceleration you mentioned is particularly interesting, that is exactly what I experienced before the repair. In my case, the faulty fuel injector was causing inconsistent fuel delivery, leading to combustion misfires especially under load. One thing I learned during my repair: the fuel pump and injector system on these engines works under extremely high pressure. When one injector starts failing, it often causes that characteristic jerking during acceleration you described. A few quick checks you can try before the workshop visit: Listen for clicking sounds near the fuel rail, Watch if the rough idle gets notably worse after high speed driving, Monitor if the check engine light flashes during acceleration The repair cost I mentioned earlier may vary, but the diagnostic process should be similar. Make sure they perform a proper fuel pressure test, this helped identify my issue quickly. Based on your mileage and symptoms, this definitely sounds like a fuel delivery problem rather than spark plugs or ignition issues.

Thanks for sharing those details, I will definitely get my Q8 checked at the workshop this week. I ran those quick checks you suggested, and yes, I can confirm there is a clicking sound near the fuel rail, plus the check engine light does flash during hard acceleration. The symptoms match perfectly with what you described, especially the rough idle after highway driving. The increase in fuel consumption and performance issues are really starting to impact my daily driving. At least now I have a better idea of what to expect regarding the repair costs and time needed. If it is indeed a faulty fuel injector causing these cylinder misfire issues, the 515 Euro repair cost seems reasonable. I will make sure they do that fuel pressure test you mentioned. Really hoping to get this sorted quickly, as the jerking during acceleration is getting quite annoying. I will report back once I get the diagnostic results and repairs completed.