You have determined that it misfires on #1 through reading data? You have also built the vehicle as 2003 STS with a 3.2 v6, which there was none. There was a CTS in 2003 that had a 3.2. Is it a 3.2 CTS, or a 4.6 STS? In either case, a misfire at idle that goes away off idle can be a result of a valve that is leaking due to poor seating, or perhaps a cam follower or broken valve spring concern.
Friday, February 18th, 2011 AT 4:05 AM