Frustrating misfire problem :(
 

So ever since i bought the car i have been having misfire problems and it has only been getting worse even though as i chase the parts down that the codes are throwing it never fixes the problem, I have changed camshaft position sensors, crankshaft position sensors, valve cover gasket due to oil being in one of the spark plugs, spark plugs, and all I have left really is O2 sensors(only new code) which weren't a problem before and I had no codes for things I have already replaced but it was still misfiring. The coil packs could also be the problem but haven't thrown codes yet but are probably my next step after O2 sensor problem is fixed since I dont know what else it could be after that. I have within the last month encountered the 02 sensors throwing codes most likely due to new exhaust setup, I was wondering what the most correct way to fix the O2 sensors messing up with a custom exhaust would be. Thanks for any input I apologize if this problem has been addressed I am just at a loss right now and getting frustrated with the circles I've been running in to fix this pos.

Have you swapped around your coil packs to see if your misfire follows?

which misfire codes are you getting? specific cylinder (p030'X') or random misfire DTC? Also going also with custom exhaust aspect and 02, by chance do you have live data scan tool to show short term and long term fuel trims?

It is a random misfire it hasn't thrown a code for a specific cylinder yet and I dont have a live data scan tool

Plug wires ?

I cant really tell if the wires are bad it is weird it only misfires after running for a while and then coming to a stop or after doing a pull it will misfire as I am driving normally again and the tachometer will bounce between zero and whatever rpm I'm at

This is a clue. Sounds electrical : Plug, wires, coil . . . . .

I really don't know for sure. Just trying to help.

Yeah that's kinda what I was thinking I know everything mechanically is good, it's to random to be mechanical, it's definitely a signal messing up somewhere the codes are for the camshaft position sensors, crankshaft position sensors and o2 sensors but it could be a bad wire harness for all I know

Hmm seems like you have everything covered. Try replacing your catalytic converters the honeycomb design is probably old and broken up inside. Even though you replaced the o2 sensors bad cats can cause problems like the ones you’re describing. GL.

I saw the cats when I put the new exhaust in a month ago, they looked new yet, should I try dummy o2 sensors?

Try it and reset the ecu then drive the car. If you still have a random misfire check the coil packs next and recheck the plugs for oil as well.

I reset the ecu and it cleared codes and drove fine for a day then next day started messing up again, I feel like it has something to do with o2 sensors, do you happen to know the most correct way to make o2 sensors not throw codes with aftermarket exhaust?

I am having the same problem... my code said cylinder one was the misfire. I was in a hurry and didn't clear the code but, this is what I did... I switch coil pack 1 and 3... code still said cylinder one misfire, but I never cleared that code, so I changed cylinder one spark plug and fuel injector, problem was still there... so today I bought a code reader, instead of using advanced auto's, cleared the code and bam the misfire was gone... then a mile down the street it started again. I put Lucas injector clear in my tank that's almost at a quarter tank... no check engine light is on so far but when I drove my car home it would go in and out of misfiring. It was weird. My next step is drive it till it throws a code and see if maybe since my coil packs are switched 1and 3, finger crossed code says cylinder 3 misfire and I have a faulty coil pack. Any thoughts or comment?

I have given up on code readers for the 350z other than Nissan's Consult.

Sounds exactly like mine, let me know if anything works haha its driving me insane

Will do... its driving me insane as well.

Okay so I finally was able to clear all codes on my 350z and drove the car while it was misfiring until it threw the code again but this time it was cylinder 3 misfire which before it was cylinder one so it came up to be my coil pack... I replaced it and now it's fixed. Problem is gone result was faulty coil pack.

What code reader did you use?

I bought the 75 dollar one from advanced auto... now this one did not tell me what cylinder was misfiring, it just told me there was a misfire... I had the use the 250 dollar one from advanced to tell me what cylinder the misfire was coming from. I was lucky enough that the employ let me use theirs. Now the expensive code reader would not clear the code... I had to use the cheap one for that.

Link to code reader I bought https://shop.advanceautoparts.com/p/...044%7CL3*16232