Engine knock while under harder acceleration.
 

I know there's dozens of threads about engine knock but I couldn't find many specifically related to acceleration.

My G35 makes a mild knocking sound while under medium-hardish acceleration. It's much easier to cause this engine knock while going up a steep hill even with a softer foot on the pedal.

All my fluids are at the correct levels, I was running 91 Octane but recently filled up half the tank with Chevron 94 octane in the hope that it will help with my issue.

It appears the higher octane may have helped a bit but I won't be totally sure until I'm able to fill it up a few more times with 94 to get rid of the 91/94 mix.

I also have a much harder time causing the engine knock when the engine has not fully reached operational temps.

Any suggestions on how I should begin to troubleshoot this issue?

Thanks.

2005, G35 Coupe, 85,000 miles