i have a 2005 nissan 350z, it started misfiring after a valve cover gaskets replacement, sounds like a bit of burbling, popping when misfiring, and smells alot like fuel. i replaced spark plugs, coils, fuel injectors, vvt solenoids, and O2 sensors. i tested: cylinder compression test (passed). cylinder leakage test (passed). smoke machine for leaks (passed). cylinder balance test (failed). This is when i figured out that im misfiring on cylinder 1 & 3, at this point the burbling makes since now that i know its running on 4/6 cylinders, it does not misfire on idle, OBD2 reads p0300 code. O2 sensors codes are still there as well after replacement, even when i erased codes. this may or may not be related to the misfire, but it gives me the illusion that its an electrical wire harness issue. help!

 

You prob have a couple coil pack plugs swapped

 

i’ll swap 1 & 3 and run the car, just to see where that puts me, but im 98% sure its in the correct locations.

 

update: bro i seriously cant believe it, that was my issue the whole time, from my thought process i thought the connections wouldn't get swapped because my wiring already formers like, in the shape it was “supposed” to be in, but after a quick rundown, it started like a factory vq engine, im so glad you commented on my post, cannot thank you enough.

 

This is more common than you would think. The harness does have the coil plugs numbered with black on white labels, but most of those labels disintegrate when touched. I recommend taking a paint pen and marking each harness plug to identify them when doing maintenance.

Not to sound like an ***, but I bet you wish you posted on here before you fired the parts canon
Well at least you got spare parts now!
Cheers!
-Icer