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Spark & Gas - what else is needed? (please don't say compression)

White smoke combined with your other symptoms is almost certainly a bad headgasket.
Sorry.

white smoke bad

Perhaps oddly, before I did anything to the car (replace plugs and a few injectors) I didn’t notice any smoke.

If you still have a cylinder flooding with gasoline and white smoke, test the injectors with a noid light or test light to be sure the the injector is being triggered properly. A short to ground or a shorted driver in the PCM can cause an injector to stay open.

An injector that’s stuck open will cause too much gas to reach the cylinder; let it stay that way long enough and it’ll wipe out the rings. Your engine’s symptoms don’t prove that the latter has already happened, nor is it certain that the injector is the issue, but taking a reading on the compression will tell you whether you have caught this problem (whatever it is) in time to fix it before the engine repairs become expensive. For that reason, I have to say what you don’t want to hear: Check the compression. If it’s OK, go for the injector. If it’s significantly low - it’s engine time. One thing to ponder: Injectors seldom get stuck by themselves. It can happen, but it’s not common, and it’s usually because of water in the fuel - which, if it happens, causes all sorts of havoc. But your symptoms are also consistent with a scored cylinder due to a broken ring, and that would be bad news indeed. Check the compression.

And a second thought: If the knock sensor code was set because the engine had been experiencing a lot of detonation, you could have an injector that has been partially plugged and feeding a dangerously lean mixture to that cylinder; in that case, the reason your plug is wet is that the piston now has a hole in it, and that’s a mixture of oil and fuel that you’re seeing on it. That is an uncommon failure, however; I doubt that it’s likely here.

Okay, so here’s an update. I spoke with my buddy who is a service manager of a Honda dealership asking for some ideas. He asked me to check my oil dipstick. As he suspected, it was way overfull. “Your car can’t make oil” so something else has entered the oil system to increase the volume. His suggestion was that a stuck open injector was flooding the cylinder, which caused the whole problem to begin with.

I changed the oil (which did have a distinct gas smell) and the filter and fired it back up. No more smoke or any of the other symptoms. It does run a little rough occasionally, so I’ll probably need to change out all of the plugs and perhaps investigate the injectors for 1, 3 and 5 - just not excited about removing the manifold to get to them.

So, the next step for me is to clear out all of the codes and see what happens next.

More to follow, I’m sure.

You’re doing it backwards. You should make replacing (or bench testing) the injectors the FIRST thing you do rather than the last. Fix the source of the problem then fix its many manifestations.

What else is needed is that all events happen in correct, timed sequence. If the spark does not occur close to the peak of compression there can be no expansion. If a valve is open at TDC or approaching it, the combustion charge will have left already. A lot of good a burnable mixture does if it is in exhaust header or intake manifold at the time of spark.