Putting the car in gear can cause the exhaust system to move and result in a rattle.

The P0300 can also be triggered by a loud enough rattle. The knock sensor is very sensitive. If the rattle is loud enough for the knock sensor to pick it up, you'll get the code.

I put it up and yeah... it sounds like the entire inside of the passenger side cat is disconnected from the casing....

Look on the bright side- now you're within the letter of the law to swap them out for a set of HFCs. :rofl2: I'll bet you can get a set of good HFCs for what one OEM cat costs.

HAH yep stock is $375 for just one side... Kinetix are $399 for the set..

Then you know what you have to do :rofl2:

Ordered the parts, but in the mean time did a data log.... wondering if anyone wants to take a look and see if they notice anything weird? Specifically between 23:07 and 23:17... It was stop sign, 1/4 to a red light, then the spark knock happened.....I'm not really sure what all I'm looking at, just curious what all the sensors think is happening.

Excel spreadsheet, delimited by comma Attachment 83815

all you have to do to be int the "letter of the law" for cat replacement is pull the upper o2's out grab a funnel, pour in some 30 weight, take it to a shop and say they are fouled, instant blown cats lol

Nissan replaced the passenger side cat under warranty for free, I did see what it would have cost if I had to pay... $976.

Later that night... I pulled the plugs...

(***to replace them... which I did but 3 miles later I had to pull them all off, to make a long story short 3 of them broke... that's another story though.. anyway***)

.. I checked the gap on the stock plugs which all were fine, put them back on, and installed newer coil packs off a wrecked 2011 with 9000 miles. This solved my idling and spark knock issue.

But now, at low RPM, only when in gear, I get valve chatter, the spark knock was masking it, as its a similar sound but now the spark knock/dieseling gone, you can more clearly hear it I've read this could be anything from crappy oil or need to run synthetic (I've only ever run 5w30 conventional oil by Castrol, Valvoline or Quaker State, even in my 350z)

I've heard of a lot of G37's having this issue, if I can I'll make a recording of it.

Try using ester oil.

So what you're calling spark knock was the dead cat rattling around setting off the knock sensor?

After they replaced the cat, obviously the rattle was gone, then I switched coil packs, which got rid of the spark knock, but now I hear... Valve noise? I recorded this by just setting my phone on the windshield, its only at low rpm, while in gear, you can feel hesitation, but when you give it gas, it goes away, and its not constant either:

http://youtu.be/Uf9PjW9PJcc

ah yes the second law of auto repair "If thou fixith one noise, thou shalt hear another"

It just sounds.. Sooo... Awful...

I was gonna say, that rattle sounds like something in the exhaust, so could be loose heatshield.

Random misses are frequently caused by intermittent vacuum leaks -- which may also cause the car to stall or the RPM's to drop as it attempts to get within the programmed idle range.

I'd check for a vacuum leak -- anything near the primary O2 could be the cause (including where the headers meet the cats), and definitely double check everything along the intake tract.

Good luck!

EDIT: wait, so you had bad coilpacks? Hmm.

Not sure about the other noise -- doesn't sound like valve tap to me. Any other symptoms?