New to the forum, thought i would give it a shot. Any information will help.

I have an 04 350z 6 speed. Service engine light comes on, scanned it and comes out P0300 (random misfire) checked all data, give me a few possible causes such as spark plugs, compression, fuel pressure, fuel injector, intake leak, lack of fuel, signal plate, heated oxygen sensor 1, and incorrect PCV valve.

I checked the spark plugs, fuel injectors, o2 sensor, pcv, intake, injector circuit. all seem to be good. what else can it be?

I also have another question, I bought a used cat but seemed to be in great condition 50K miles on it because mines gave up on me and it destroyed what was inside, once i replaced it i drove it and it got EXTREMELY hot and when i got out the car i see it smoking and the cat is burning RED... i made sure the bolts were on tight and they were, but i never replaced the gasket after the change of cats, does that actually matter? or is the cat just bad?

ALSO it says THE CRANKSHAFT POSITION SENSOR.. Is there a special way to put it in? I mean there is only one way to put it on but does it matter? I did change my clutch and flywheel so i did take it out..

Thank you.

anything helps.

 

I also have an 04' and have come across this problem a couple times. I read everything so if I repeat what you've done I'm just going through the "check list" for this situation. I'd also recommend investing into an OBDII reader for future situations..

-Check for vacuum leaks (intake, disconnected hoses, exhaust, etc) Make sure all your exhaust nuts/bolts are good. I had a couple that got mangled from who knows what.
-Check O2 sensors. Make sure they're fully tightened, cables are not ripped/frayed, and that no air is escaping.
-Check your Camshaft Sensors (Bank 1 tends to fail first (backside of passenger valve cover))
-Check Crankshaft Position Sensor (Sensors from AutoZone will be fine or if you'd like Z1motorsports.com have OEM)
-If none of those solve your problem I'd get your spark plugs/coil packs checked at a reputable shop or if you have the tools/knowledge to do so

When you installed the new cat did you check to make sure the honeycomb on the inside was in good condition?? I've personally never seen a cat get red hot like you describe from casual driving so it could possibly be clogged/becoming clogged... I'd check the cat before you do anything else. Reusing the OEM exhaust gaskets should be fine. Hope this helps man.

EDIT: Sensors are plug and play. They're straight forward.. when it's connected, it's connected. Your Crankshaft PS should be fine unless you mangled it from taking it off/on. The Knock, Crankshaft and Cam Position Sensors tend to go out on the earlier model Z's so don't fret. It's as easy as buying a new one and plugging it up.

 

Hope you guys dont mind if I piggyback on this

I started throwing p0300 codes a week ago. Drove fine but made a whining sound at WOT. Cant seem to get it started now although it seems to want to crank over. It would link and turn off every once in awhile. Ive got it narrowed to the plugs (NGK Iridium changed 25k ago), 99k oem coils and maf. Any other possibilities? I gotta get it fixed soon because I need to be able to drive, and if its a coil or maf issue Im not paying someone else to do it.

Edit:
Also my Crank PS was changed roughly 30k ago, that was a different code.