NHTSA Complaint #11562886 — 2017 KIA FORTE

Starting around 50k mileage, the engine experienced misfire-like issues: rough idling & transitory reduction of power during acceleration and cruising. This was brought to the dealership multiple times, but the check engine light had never come on, nor were there any error codes saved in the OBD system. After 60k mileage, the check engine light did come on temporarily, but would automatically clear, still without any error codes saved in OBD. Around 65k mileage, the vehicle could not accelerate to highway speeds, so I had it towed to the dealer and refused to take it back until they found the issue. They then observed an error saved in OBD showing a misfire on cylinder 3. Replaced all spark plugs + coil packs, which seems to have corrected the problem. After 70k mileage, I observed that the engine burns oil, about 1 quart per 3k miles. This rate has stayed consistent up to the current 100k mileage.