Help! I'm stuck in P0300 hell
 

I really need some help here. I can't register my car until I pass emissions but I keep running into the P0300 code. The city is about to fine me for not having a tag (even though its in my driveway) and my landlord is threatening to tow it for the same reason.

Basically I'm screwed if I don't get this figured out soon.

Info: 2003 Z, intake, OSIRIS reflash, and currently running open cats since I don't have a mid pipe.

The problem first appeared the day after I first drove it. I narrowed it down to a coil pack by doing the "unplug" trick on each cylinder. Replaced the coil pack with a brand new OEM part. Misfire seemed to be gone but the code came back after about 30miles. This has happened twice since, the most miles I've been able to run before it comes on is 92. I haven't heard any audible misfires but the car does seem to hesitate (feels jerky/slow) under 3k RPM. This seems to be worse when I'm not getting on it. My reflash was done for a car that doesn't run cats since I'm planning on running test pipes.

So, any ideas on what I'm dealing with here? If I can't get it figured out soon I'm going to have to register in a different state and that's kind if a pain in the ass hahaha.

Thanks, BJ

92 Miles should be enough to pass inspection.

Get rid of the OSIRIS flash if it started happening after you got that done

Take the exhaust back to stock, Pass emissions and then put it back on...(not the politically correct way)

Spark plugs been replaced recently?

The car has only run on the Osiris. I bought it in pieces so I just now got it running. As for the exhaust I don't have a midpipe. Checked all the plugs (theyre brand new) before I did the coil pack replacement. All looked good except the one with the bad coil pack.

I was less than 2 miles from the emissions place when the light came on again lol

is it a sniff test or are they just flagging you for the code? idk the rules up there.

BTW here is a good starting point/checklist.

https://my350z.com/forum/maintenance...eshooting.html

Thanks man. On cars this new they do the obdII port. I have addresses in Florida and North Carolina that I can register at but is much rather do it up here

register it in a non emissions county get inspected, boom done

That's what I'm trying to avoid doing. I've done it with all my other cars but I'd really like to avoid going through the whole "why do you have a ga drivers license and fl tags" thing when I get pulled over.

There's also the fact that if something is actually causing it to misfire I'm putting my motor at risk by ignoring it.

Did you read this thread...

https://my350z.com/forum/maintenance...o300-code.html

Hadn't seen that but definitely worth a try. Does anyone have any tips on unplugging the injectors with the IM still on the car? Also, if I had a bad injector would unplugging the corresponding coil pack make any difference at idle? I'm wondering if maybe the injector is faulty.

Another thing I forgot to add. The car sat for 3-4years before I got it. Had some gas in it still but not much an I have refilled the tank twice since I started driving it. Is there any real way to clean the fuel tank, lines, injectors, etc? I'm always skeptical of those additives that are on the market.

Ok so I'm still dealing with this crap. Yesterday, cleared the codes and drove about 50mi before my SES light came on. Reading was P0300 and P0444 (evap solenoid). Anyway cleared them and them today I got the p0300 again along with 2 o2 sensor codes. Cleared those and went for a drive. Now the SES is randomly turning on and off. Usually cuts on when I hit the gas but turns back off when I let off the throttle. Also stays on til about 3k rpm, cuts off, comes back on at 3250, and then turns off again above 3500.

I'm lost. Could this be an issue with my OSIRIS reflash or do I have a gremlin living in my motor?