Okay, I just bought a 01 Prelude qith around 100k on it. About two days after getting it, I get the dreaded engine light. After pulling the codes, it was the oxygen sensor before the Catylic Converter. After replacing that, I now get another code telling me that the system is too rich. Could it be the other sensor? I'm running 93 octane if that matters.

And then last night when I started it up, there was a horrible knocking noise. I honestly expected a rod. After a few minutes though, it went away. I went on my way and it was still there this morning. I checked the timing belt to make sure it was tight, but thats not it. I took it to a shop and they told me that it was just "Piston Slap." He then told me that the car had been driven very hard in it's life and that an engine rebuild would be needed in the future. It seems to only happen until the motor warms up.

Any kind of insight is great.