Hey Scotty love the channel. I have a 97 Infiniti QX4 (pathfinder) and has a misfire p0300. I’ve replaced plugs twice, wires, and distributor twice (warranty). Check engine blinks sometimes as you can imagine. I took it to a shop and was told it needs 3 injector 2,4,6. I removed the upper intake manifold to replace number 6 cylinder injector and noticed that there was no carbon buildup on the intake manifold of that cylinder like the other 5. I Replaced the injector and no change. After replacing plugs the first time it seemed to run better for a short amount of time after full operating temperature but seems to dislike the cold very much here in Iowa. The plug on cylinder number 6 is usually wet when removed. The oil smells of raw gas. Any ideas? Blockage in the return fuel line causing gas to dump in cylinder number 6 and maybe a few others?
The thing that jumps right out is the diagnosis of bad injectors on cylinders 2,4, and 6.
What are the odds that ALL of the injectors on bank 2 of the engine ALL failed at the same time while all of the injectors on bank 1 are fine? .... hmmmm.
You say the oil smells of raw gas. You also say that the cylinder 6 spark plug is "wet when removed" that intake port lacks the carbon buildup which is evident on the other cylinders.
You may want to focus your attention there.
You replaced the cylinder 6 injector.
It's certainly not leaking. We also know that injector is getting power and ground because the spark plug is wet.
The computer is supposed to provide the ground signal to open the injector.
What if the injector's #6 cylinder ground signal wire is "shorting to ground" and keeping that injector open?
Maybe put a noid light on that #6 injector connection to see if it's pulsing or staying lit.
If it's staying lit then examine that injector's ground signal wire.
The symptom seems to be pointing to 1 of 2 things.
Either that injector is staying open
or that cylinder isn't getting spark.
Maybe put a spark tester light on that #6 spark plug too.
Something isn't working right.
No matter how you decide to proceed, if you're presently still running the car, change the oil/filter. It will cost maybe $40 bucks tops.
You can't have your oil diluted with gasoline.
That could really complicate things
Misfire are covered in the FAQ (first topic on main page)
