Lean cylinder misfire

[David Schuman]

2007 aveo, 198,000 miles. Cylinder 2 misfire, spark plug very slightly white. Replaced coil pack, plugs, wires, (ac Delco) both O2 sensors (ntk) oem. Fuel pressure is normal. Problem remained. Could it be the Cat? Thanks for any help!

[avguy]

Very unlikely that a single cylinder misfire is a cat issue. Try swapping the #2 injector with another, in order to see if the misfire follows the injector.

[David Schuman]

We replaced the #2 injector with new AC Delco one, and the problem persists. Car set for several months with little usage, then I started driving it. Ran fine for a couple of weeks, then this issue popped up. I might have done something wrong by putting a bottle of fuel injector cleaner in with a full tank of gas when I started driving it after it sat for several months?

[avguy]

Also very unlikely the injector cleaner used the way you described caused the problem. You need to find out if the problem is fuel, spark, or compression. Start by removing the plugs, in order to compare them to see if #2 looks different than the others. Clean them all up, and repeat a few times if necessary to see if any helpful clue shows up.