Averying's 2009 Platinum Graphite 370z Journal

Averying

Well I’ve been chasing down a misfire for a few months now. Started off only happening on start up, and eventually the car really struggled after ~2.5k rpm.

A few days ago I started up the car for the first time in months and I was getting the same kind of misfire, and I had a P0305 code (cyl #5 misfire). I swapped the #5 and #1 spark plugs and coil packs and now I’m getting a P0300 code (multiple misfires), but the car starts up and misfires (intermittently it seems) in the same exact way as before swapping the parts between cylinder.

I also had an O2 sensor code in the past but I attribute that to my cracked test pipe, which is now fixed. That O2 code hasn’t come back during my jack-stand start ups this winter.

What I’ve tried already:
1. Fixed cracked test pipe and there aren’t any other noticeable exhaust leaks from the test pipes back.
2. Cleaned MAFs.

My next steps to diagnose the issue:
1. Run a mode $06 DTC scan and see if I can determine which individual cylinders are getting misfire codes. Hopefully this is a function I have in my OBDLink MX+ reader
2. Check that the fuel pump top hat hasn’t broken. I’m really hoping that this IS the issue. Obvious problem means easy diagnosing.
3. Run the car without air filters. Admittedly my cone filters are pretty old so if these are causing a restriction, taking them off briefly will indicate that. They were “cleaned” a year ago… but I am probably due for a new set.
4. Take out and clean injectors and throttle bodies.
5. Replace O2 sensors?? I don’t think this is the issue. Not throwing an O2 sensor code anymore
6. Cry

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2009 Sport Touring | Platinum Graphite | GTM Stage 1 Supercharger | BC BR Coilovers | Hotchkis Swaybar | Z1 FUCAs | AME TM-02 Wheels | Z1 2-piece Front Rotors | Z1 Clutch & Flywheel | Invidia Gemini Catback | GTM Resonated Test Pipes