03-12-08, 02:35 PM
We inherited a 2003 Deville from my fathers estate. It was always maintaied at the dealership and has only 30,000 miles. It ran beautiful until one day it started missing and the check engine light came on. I was involved in an accident and the front drivers side fender, grill, etc. was damaged. It was painted. We had it diagnosed and it was misfiring on plug #5. Our mechanic pulled it and said it was ok. We took it to the dealership here in town, and they diagnosed it as both coil packs needing replaced. They said they would need to do a repeat $170. diagnostic on it after the $917. repair to be sure there isn't something else wrong. We switched to 5w-30 synthytic oil about a week or so before the misfire started. Also we were told that the ethanol gas mixture could be causing a problem. The tech at the dealership said it was an environmental issue, whatever that means! The only thing I can think of is the body shop using heat lamps with the hood up to dry the paint. Could this be a possible cause for the coil packs to malfunction? Could there be something else causing the misfire?