S8 Coil Pack Issues Causing Rough Running and Stalls

I had nearly identical symptoms on my 2018 S6 last summer. As someone with some basic maintenance experience, I first suspected a misfire when the check engine light started flashing during acceleration. The engine would run rough at idle and occasionally stall, especially after cold starts. The jerking sensation during acceleration was also very similar to what you describe, classic signs of coil pack issues. Took it to my regular workshop where they diagnosed a faulty wiring connection to one of the coils. The cable insulation had worn through, causing intermittent connection problems. Total repair cost was 95 Euro including diagnostics and fixing the wiring. Before suggesting more specific advice, could you share: Current mileage, When was the last spark plug change, Are all cylinders affected or does it feel localized to one side, Does the check engine light flash or stay constant, Any recent work done on the engine This information would help determine if your issue matches what I experienced or if it might be something different.

Thanks for your reply. My S8 has 148403 KM on the clock and the ignition system was last serviced during regular maintenance 6 months ago. The check engine light stays constant rather than flashing, and the rough running seems more noticeable on the driver side of the engine. The vehicle diagnostics readout shows misfires, which align with potential ignition coil failure symptoms. Your experience with the wiring issue is interesting, I noticed the problem started shortly after some heavy rain, which could suggest a similar electrical connection problem.

Thanks for the additional details. Based on the mileage and symptoms you describe, your situation seems different from what I encountered with my S6. While my issue was purely a wiring connection problem, yours appears more consistent with actual ignition coil degradation. The constant check engine light combined with misfires showing in the vehicle diagnostics strongly suggests coil pack failure rather than just a loose connection. The fact that the rough running is more pronounced on one side helps narrow down the problem area. After experiencing my wiring issue, I learned these engines are particularly sensitive to ignition system problems. Since your symptoms started after rain exposure, moisture might have accelerated the deterioration of an already weakening coil. In my case, the repair was simple because it only involved fixing the wiring. For your situation, I recommend having all coils on the affected side replaced as a set. When one coil shows signs of failure, the others are likely not far behind. This preventive approach helped me avoid repeated issues later. Would suggest checking if there are any technical service bulletins related to coil pack failures for your specific engine. Some production runs had updated parts available that offer better moisture resistance.

Thanks for the input. After considering the feedback and comparing symptoms, I've decided to take my S8 to the shop tomorrow. The evidence seems pretty clear, constant check engine light, confirmed misfires in the diagnostics, and rough running focused on one side all point to coil pack issues rather than just wiring. The timing with the rain exposure makes sense too. I appreciate the suggestion about replacing all coils on the affected side. Given the mileage and age, this preventive approach sounds like the smart way to avoid future problems. Will also ask the shop about any updated parts with better moisture resistance. The spark plugs are relatively fresh from the service 6 months ago, so at least that's one thing I can rule out. Will update once I get the official diagnosis and repair completed. This forum has been really helpful in narrowing down the likely cause before heading to the shop.