I have to wonder if the PCV is bad...and if oil was coming in at quantities that favored the condition you had on #4.
I would hate to think the PCV was bad. The valve covers and PCV valves I had installed post engine swap were all brand new. When I was looking for vacuum leaks a couple weeks ago, the PCV and vent from the valve cover were routed to the same catch can to the intake pipe. I when I separated the PCV from the catch can and ran it back to the intake manifold, I connected it to the port on the Altima plenum behind intake runner #1, so I would think cylinder 1 should’ve been most affected by oil but the misfire remained on #4. The amount of oil seemed about equal on all intake runners when I was looking at it earlier today. The oil definitely wouldn’t help, but I don’t think it’s the main cause of my misfire.
I want to believe that the injector I swapped from 4 to 3 is flowing more fuel than the others. My narrowband O2 sensor going to the ECU is on exhaust runner #4, so the ECU should be adjusting A/F ratios based off the information from the MAF sensor and the cylinder #4 A/F. My wideband O2 sensor is lower on the manifold where the runners collect so it’s seeing the A/F ratio of all cylinders. What I believe is happening is that the injector I swapped from 4 to 3 is still flowing more fuel, but the ECU isn’t seeing it since it’s on cylinder 3 now. So the A/F ratio looks good and theres no misfire according to the ECU, but the wideband sees the richer A/F ratio from all cylinders collected.
I’m a little irritated by the inconsistency of the fuel injectors. There’s no check engine light anymore, but I don’t really want to leave them alone now that I know they aren’t right. I think I’ll get a brand new set instead of a remanufactured set this time, but I’m going to take some time to consider whether I should go stock size or upgrade for e85.
As for the coil pack issues, I want to believe that the fuel injector was spraying a large enough mass of fuel to make it difficult for the plugs on cylinder 4 to make spark. The extra resistance at the spark plug would put more load on the coil pack and “make it work harder,” pushing more current and wearing it out prematurely. High current and high temperatures (like the engine bay temps) kill the lifespan of electronics.
Edit: I’m going to email the 2JR guys and see what they think. I bought the injectors from them so maybe they can send me a good one, or give me advice on whether upgrading and going to e85 is a good idea.