ls engine random missfire and sooty plugs on one side

[dsraven]

just had the random misfire code and, when checked, sooty/carbon fouled plugs on one side of the engine. the plugs on the other side were all normal. did some quick fuel pressure tests and flushed the injectors, same problem. swapped out the precat o2 sensor on that side and cleaned the plugs, all good now. gonna run it for a day or 2 and then do a tune up and fix that annoying exhaust leak from broken manifold bolts. can't wait for that drivers side manifold........

[BR3W CITY]

I'm not sure if there was a question in there, or if that was all a statement....but if you do have a large exhaust leak at the manifold, that itself will cause you to misfire on that side.

The large amounts of clean air will throw off the 02 readings and it will try to compensate using short term fuel trims. The ecm will demand a higher injector cycle from that side, which will intern be VERY rich since the actual amount of air on the intake side hasn't changed. That rich mixture will burn sooty in the combustion chamber, and gunk up your plug like that.....then since the spark is diminished slightly, the next power stroke it'll be rich again even worse. Each time that happens, the spark will get worse but it'll still run rich, as it'll never have a hot and lean enough combustion cycle to clean off the electrode on the plug.

[dsraven]

my exh leak isn't so bad. only really hear it when it first starts up cold. broken bolts on the ls is common, i have it on both sides.