Tribeca Misfire Issues: Bad Coil Pack Warning Signs

I had nearly identical issues with my 2012 Legacy last year. Having some experience with basic car maintenance, I initially tried diagnosing it myself using a borrowed OBD scanner, but the symptoms were exactly as you describe, rough idle, jerking during acceleration, and constant misfires. After attempting basic checks, I took it to my regular workshop where vehicle diagnostics revealed a damaged wire connection to one of the ignition coils. The cable insulation had worn through, causing intermittent coil failure and engine stalling. The total repair cost was 95€, which covered the diagnostic work and fixing the faulty connection. The symptoms you describe strongly suggest an ignition system problem, but it might not necessarily be a bad coil, could be wiring or connections like in my case. These issues can be tricky to diagnose without proper testing. Could you share: Which engine size you have? Does the problem occur more when the engine is cold or warm? Have you noticed the issue getting worse in wet weather? Do you have any stored error codes? This information would help determine if your issue matches what I experienced with the wiring problem.

Thanks for the replies and questions. My Tribeca has the 3.6L engine and the misfires definitely get worse when the engine is warm. Last service was done 2 months ago where they changed oil and filters. I did notice the issue is more pronounced in wet conditions. Regarding error codes, my basic scanner showed P0301 and P0303, which points to misfires in cylinders 1 and 3. The engine stalling happens pretty out of nowhere but mostly at idle or low speeds. Based on what you described about the wiring issue, I will have them check the coil pack connections too when I take it in. Given that multiple cylinders are affected, I am thinking either the wiring harness has deteriorated or maybe we are looking at coil failure in more than one spot.

Thanks for the update. Those symptoms are remarkably similar to what I experienced, especially the P0301 and P0303 misfire codes and the sensitivity to moisture. In my case, the wiring deterioration was affecting multiple coil packs, which explains the dual cylinder misfires. With the 3.6L engine having individual coil packs for each cylinder, water intrusion through damaged insulation can definitely cause these symptoms. The fact that your issues worsen with engine heat and moisture strongly suggests a wiring problem rather than just faulty coil packs. When my mechanic dug deeper, they found the insulation had broken down in several spots along the ignition system wiring harness. The heat from the engine had made the problem worse over time. The repair involved replacing sections of the harness and properly sealing all connections to prevent future moisture issues. The total fix ended up requiring: Full ignition system diagnostic testing, Wiring harness repair, New coil pack connectors, Resealing of all connections The complete repair cost was 280€, which was actually cheaper than replacing multiple coil packs. Since the fix, I have not experienced any more misfires or engine stalling issues, even in wet conditions.

Based on this new detailed information, I really appreciate the insight about the wiring harness issues. The check engine light and misfire codes definitely match what could be a systemic wiring problem. I will have my mechanic thoroughly inspect the wiring harness and coil pack connections when I take it in next week. The fact that your repair cost was 280€ for a complete fix gives me a good baseline for what to expect. Much better than potentially replacing multiple ignition coils unnecessarily. The similarity between our issues, especially the moisture sensitivity and dual cylinder misfires, makes me more confident about the likely root cause. I will make sure they specifically check for deteriorated insulation and proper sealing around all the coil pack connections. Once they complete the vehicle diagnostics, I will update this thread with what they find and the actual repair costs, since this seems to be a common issue that could help others with similar symptoms. Thanks again for sharing your experience. This kind of detailed real-world feedback is exactly what I was hoping to get before heading to the shop.