Q8 Hybrid Misfire: Ignition Coil Warning Signs

Having dealt with similar symptoms on my 2021 Q7 hybrid, I can share my experience. My engine also had rough running and stalling issues, accompanied by a check engine light and misfires. After some initial DIY diagnostics, I brought it to a workshop where they found a cable connection issue affecting the ignition coil. The symptoms match yours exactly, jerky acceleration, rough idling, and occasional engine stalling. The technician explained that loose or damaged wiring to the ignition coil can cause these intermittent problems, particularly in hybrid powertrains. The repair was straightforward, costing 95 Euro to fix the faulty wiring connection. Since then, the misfire problems and check engine light have not returned, and the engine runs smoothly again. To better assist with your specific case, could you share: Current mileage, When the symptoms first appeared, Whether the check engine light is constant or flickering, Any specific error codes from diagnostics, If problems occur more during cold starts or warm engine With this information, I could provide more targeted advice based on my similar experience with coil failure symptoms.

The engine hesitation started shortly after my last service at 192340 KM. Initially, I suspected spark plug issues, but the diagnostic scan pointed to ignition coil problems. The check engine light flashes intermittently during acceleration, and the misfire seems most noticeable when the engine is cold. The error codes from my scan tool indicate a cylinder 3 misfire. I am wondering if replacing just the faulty ignition coil would be sufficient, or if I should consider replacing all coils as preventive maintenance. A complete ignition system overhaul with new coils runs about 450 Euro at my usual shop. The hybrid system otherwise works fine, it is only when running on the combustion engine that these issues occur. Good to hear your repair was relatively simple and cost-effective.

Thanks for providing those details. Based on your mileage and symptoms, I would recommend replacing all ignition coils rather than just the one showing issues. When I faced similar problems with my Q7, I initially only replaced the problematic coil in cylinder 2, but within 6 months, another coil pack failed. The flashing check engine light during acceleration strongly indicates an active misfire, which matches the coil failure pattern I experienced. Cold start issues are particularly telling, as faulty coils often show their worst symptoms before the engine warms up. At your mileage point, preventive replacement of all coils makes sense. While 450 Euro might seem steep compared to my simple wiring fix, it could save you from repeated workshop visits. In my case, I ended up spending more by replacing coils individually as they failed. Given the integration between combustion and hybrid systems, reliable ignition is crucial for smooth operation. Since your spark plugs were likely changed during recent service, focusing on the coil pack replacement should resolve your engine performance issues. Would you like me to share the specific diagnostic steps the workshop used to confirm my coil failure before proceeding with repairs?

Looking at your recommendations and my situation, I think I will proceed with replacing all ignition coils. The flashing check engine light and cold start issues match the symptoms you described perfectly. My initial hesitation about the 450 Euro cost makes less sense now, especially considering the potential hassle of multiple workshop visits if I only replace one coil at a time. The diagnostics already confirmed the cylinder 3 misfire, and given the integration complexity of the hybrid system, I want to ensure reliable ignition system performance. My spark plugs are indeed new from the recent service, so focusing on the coil pack replacement seems like the logical next step. I appreciate your insight about the cold start symptoms being a telltale sign of coil failure. This matches exactly what I am experiencing, particularly during morning starts. I will schedule the complete ignition coil replacement this week to prevent any potential damage from continued misfires. No need for additional diagnostic steps, your experience has helped confirm what I suspected about the ignition system issues. Thanks for helping me make an informed decision about the repairs.