So I have a 2003 G35 sedan MT a few months ago. Engine started making ticking noise at 2500-4000rpm. The ticking is only from one cylinder (cylinder 6). Did motor flush and oil change with Mobil 1 super synthetic 10w-30 oil and added Lucas oil stabilizer. I only use 93 octane fuel from shell or mobil gas stations. Nothing is helping and I can’t find a direct answer online. There is NO loss of power since noise started.

Every few weeks it will have low idle and stuttering when revving/accelerating, but it goes away after a couple seconds.

Is it bad valves? Timing? Please help!

I have a video of the noise on youtube, here's the link:

 

First thing I'd check is to be sure the plug is fully tightened, sounds almost like an exhaust leak. Fuel injectors can tick, so can valves out of adjustment.

 

 

#6 cylinder. Not sure if it is common with the VQ35 but notoriously common with Honda J series V6 engine for spark plugs to back out and make a ticking sound.