Changed the plugs, valve springs & seals. The #2 Plug was black. All of the others looked good. I have driven it about 100 miles since the new plugs were put in. During the 100 miles, I was getting stumbling at low RPMs during light acceleration and a code 44 came up. Lean Exhaust. Took the #2 plug back off and it was wet. Any ideas what to check? Ignition wire?

 

O2 sensor would be the first thing i would fire into the nieghbors yard.

If its picking up lean a/f ratio and the plugs are black that would be the first thing i would suspect.

Pull a few more plugs to make sure all holes are running that rich.

 

All other plugs are fine.

 

If all but one of the plugs are a nice cardboard brown i would check compression in that jug.

If it checks good check the spark and valvetrain.

 

Could be an ignition problem causing misfirings, an exhaust leak causing a false lean condition, a bad/grounded O2, faulty fuel pump, clogged fuel filter, and probably other things that I havnt mentioned.

With an FI car, under normal engine operation the plugs will be bone white most of the time due to the fact that its running around stoich.

 

Just saw that the #2 plug was wet. Sounds like a dead cylinder. Could be the problem stated above, or it could just be a bad wire, or it could be something else. The even cylinders wont cause any issues with the O2, though, as the O2 only takes readings off of the odd numbered cylinders. Are there any other cylinders with similar issues?

 

Spark Plug Wires look OK, replaced fuel filter, Cap & rotor look OK, No exhaust leaks, ran bottle of injector cleaner through gas tank. No help so far.

Could valvesprings cause the problem. I just replaced all the springs & seals. And its possible I overtightend them.

 

You could have wiped a lobe on the cam or something to that extent.

 

I would do a compression check on that cyl before I did anything else. If thats' good, swap the plug wire with a known good one. Check for vacuum leaks near the #2 cyl.