2002 silverado, 4.8, pacesetter lt's ORY, stock intake, ported TB, Futral tune.

It started out as a miss at idle when cold outside. after searching and seeing intake gaskets as the culprit i replaced them today. while i was at it i finally got around to pulling/replacing a broken header bolt. now that it is reassembled on the first test drive, within a minute of driving it started to miss at idle real bad (was idling around 400 or so). came home, triple checked all connections, all were good. put a timing light (just to check fire) and it seems that the entire drivers side was sporadically getting fire. pulled the main coil pack plug off, put dielectric grease and put back. long story short i thought all was well and after just running the the store it ran great for about 15 minutes then started acting up again.

sorry its so long, didnt want to leave out details

 

check your fuel trims. could have killed o2 sensor.

 

i have no way to check the fuel trims

 

unhook the battery so everything will reset. disconnect both o2 sensors and see if it clears up.

 

alright, disconnected batt and 02s went for a ride and it seems to be fixed. shouldnt having the 02s disconnected caused a cel though? it didnt... drove around till at operating temp too.

 

finally broke down and bought an actron scanner... glad i did. bank 1 sensor 1 pretty much hangs out at .040-.050mv!! guess i need a new un! must have beat it up a little bit when the header was hanging the other day while i removed a broken header bolt

 

You would eventually get a light with them unplugged. The sensor failed at a lean voltage and the PCM kept adding fuel to that bank trying to make it go rich. So much fuel that it was soaking the plugs. If you would have been able to Check fuel trims they would have been maxed positive.

 

the trims were maxed... the sensor was failing at .080mv, so yea... a little lean lol. swapped it out with a rear working o2 and all is well now! thanks for the help!