SQ5 Misfire Issues: Coils vs Other Ignition Problems

Had a similar issue with my 2012 S4. The symptoms you describe match exactly what I experienced, engine hesitation, rough idle, and stalling issues. After some troubleshooting, it turned out to be a loose connection in the wiring harness connecting to one of the coil packs. The check engine light was definitely a wake-up call. Initially thought I needed to replace all coil packs, but the workshop found it was just a damaged wire and connector. Total repair cost was 95 Euro, which included diagnostic time and fixing the connection. For someone with moderate experience working on cars, I was glad I didnt jump straight to replacing parts. The ignition system can be tricky, and electrical issues often mimic coil pack failures. To better assist, could you share: Have you scanned for specific error codes? Does the engine hesitation occur more when the engine is cold or warm? Are all cylinders affected or does it feel like just one is misfiring? Any recent work done on the ignition system? These details would help determine if youre dealing with the same issue I had or if its something else in the ignition system.

Thanks for sharing your experience. I also have 52139 KM on the clock since my last service. My error scan showed P0301 and P0303 codes. The engine hesitation is definitely worse when cold, especially during the first 10 minutes of operation. The vehicle diagnostics suggest misfires mainly in cylinders 1 and 3. No recent work has been done on the ignition system. After checking the wiring based on your feedback, I noticed one of the spark plug boots appears slightly loose. I wonder if this could be causing the stalling and rough running issues rather than complete coil failure. The engine hesitation seems to match your description of a connection problem rather than failed components. Has anyone else dealt with loose connections causing similar symptoms? Before I spend money on new coils, I want to make sure I check all connections thoroughly.

Thanks for those additional details. After dealing with similar issues on my S4, the error codes P0301 and P0303 combined with the loose spark plug boot strongly point to a connection problem rather than faulty coil packs. The cold-start symptoms match perfectly with what I experienced, loose connections often cause more problems before the engine warms up due to thermal expansion. The check engine light in my case also triggered multiple cylinder misfire codes. Before replacing any parts, try these steps that worked for me: 1. Remove and inspect all coil pack connections 2. Check the rubber boots for signs of wear or damage 3. Verify proper seating of all ignition system components 4. Look for corrosion on connector pins The vehicle diagnostics should show improvement once connections are properly secured. When I fixed my loose connections, the engine stalling and rough idle issues disappeared completely. Total repair cost if you need new boots or connectors should be under 50 Euro, much cheaper than replacing coil packs unnecessarily. Just ensure all connections are tight and properly seated when reassembling. Let us know what you find after checking the connections. Based on the similarities to my case, I suspect this will resolve your engine performance issues without major parts replacement.

Thanks for the helpful advice. I followed the suggested inspection steps and found two issues: the loose spark plug boot on cylinder 1 was actually cracked, and the connector for cylinder 3s coil pack had corrosion buildup. After cleaning the corroded connector and replacing the damaged boot for 35 Euro, the engine hesitation and rough running have completely disappeared. The misfire codes are now gone and the check engine light has turned off. The ignition system is working perfectly, no more stalling or jerking during acceleration. Really glad I checked all the connections before jumping to replace the coil packs. Total repair cost was much less than I expected and the engine now runs smooth even during cold starts. For anyone else experiencing similar symptoms, definitely inspect all ignition system connections thoroughly before assuming you need new coils. Sometimes the simplest fix solves what seems like a major problem. Thanks again for helping me diagnose this correctly.