what someone suggested to me is this:

1. start engine, rev to make sure noise is still present

2. unplug coilpack #1, rev engine. if sound is still present, replug in, goto cyl #2

3. unplug cyl #2 coilpack, rev, if sound is still present, replug in, goto cyl #3

4. continue doing this until the sound goes away. if the sound goes away on one particular cylinder being unplugged, then that particular cylinder/rod may have knock.

5. if the noise continues regardless of which one is unplugged, then your problem could be elsewhere.