Originally Posted by TedB370z

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.