Need help finding misfire

[Will]

My car is throwing a code for 1st cylinder misfire. Its not the multiple misfire code where the ses light flahes. I cannot notice any hesitation or jumping from the car. I cannot tell any power loss. The only symptom i am having is decreased gas mileage. My cars plugs and wires are under 20,000 miles. I thought it might be a coil pack but the coils control 2 cylinders each and only one is misfiring. When its been plugs or wires i can always tell a good power loss and alot of jumping but everything is smooth. Its just throwing the code and is getting alot worse mileage. Anyone have any idea what this could be?

[RallyRed 98]

worse mileage is sometimes a good indicator of a bad O2... did you get that code or just the cyl 1 misfire?

[Will]

I got the code for 1st cylinder misfire and 2 codes for my o2 sensors but my o2's always throw the codes because of my headers. My SES light has always been on for the o2's but it has just come on for the misfire.

[Turbo V6 Camaro]

Originally posted by Will:
I got the code for 1st cylinder misfire and 2 codes for my o2 sensors but my o2's always throw the codes because of my headers. My SES light has always been on for the o2's but it has just come on for the misfire.

replace your Os the headers breaking in kill the O2's

also try moving plugs wires and see if the miss moves too [img]smile.gif[/img]

[Will]

so after replacing the o2's the headers wont kill them again? I have had the headers on for about 6-8 months and i have just now got a code for 1st cylinder misfire this week.