Here is a follow-up for the problem below:
I put a OBDII code reader on the car and learned that the actual code being set is P0303 which is a misfire on cyl #3.
I swapped the wires between cyl #3 and #5 (both ends of course) and the fault stayed with cyl #3.
I then swapped plug #3 with plug #2 and the fault followed the original cyl #3 plug. I now have code P0302 set.
The plug in #3 had a bit of black carbon on it and the center electrode was somewhat brown. The plugs in #2 were a light gray color with no deposits. I also checked plug #8 which is the other plug on the same coil as #3 and it looked light gray in color also.
All the plugs- #3, 2, & 8 had gaps from .065 to .085 with the spec at .050. All had rounded center electrodes.
QUESTION: Is it fully reasonable or wildly optimistic that plugs will last 100K miles? I am tempted to just replace the one plug and return the wires to their original positions. I hate to spend money for parts that are really good. Plugs are $5.50 and a wire set was $103.
A related question: Does anyone know how to query the computer to give a count os misfires on each cylinder? My OBDII system is just an interface to my laptop and apparently the GM recommended scantool is capable of showing counts of misfires on each cylinder. That would be very useful. I will post this question separately also.
TIA, Rich
Rich wrote: