An ignition coil may fail causing one of the cylinders to misfire. Each of the two banks of cylinders has its own coil assembly. If one ignition coil fails the coil assembly for the corresponding cylinder bank must be replaced.Google+
Car Problem Reports
Cadillac DTS Misfire Due to Failed Ignition Coil
Cadillac DTS Problem
Average Mileage: 120,000 mi (115,000 mi - 125,000 mi)
Engine was misfiring. Took to shop where cylinder one coil was verified as needing replaced. Once replaced, misfiring stopped.
misfire found in one cyclider...replaced 2 ignition coils so far, spark plugs twice, and all oil gaskets in the engine...Over $5K into fixes and it's having the same issue again.