I have a 350z 6MT and it is currently throwing a P0300 (Random/Multiple Misfire). I did many things and I cant seem to find the problem. It was recently engine swapped because the old one spun a bearing at 140k. I swapped a G35 ( VQ35DE ) engine in and it was missing. I changed the plugs, the coilpacks, crankshaft position sensor, camshaft position sensor ( driver and passenger side ), changed fuel rail and injectors, changed ignition coil sub harness. I have no idea what to do. Any advice?

 

Are your injectors leaking?
Are the plugs properly tapped?
Was everything installed correctly?
Was the motor damaged before you got it?
Have you been racing it?
Are there mods on the car?
Have you done a vaccume leak test?

 

No injectors are good, yes plugs are good, everything was installed correctly, no motor wasnt damaged and did a compression test it was all good aswell. And yes did a vacuum leak test. Im thinking maybe a wiring issue im hoping not

 

are you 10,000% sure you didnt swap coil plug #6 and #4? They are inherently/logically backwards?

Take a picture of your driver side bank and post it.

 

this 99% of the time. Nissan makes it too easy!

 

I know I'm bat-**** crazy ...

 

Yeah, hate to agree with you but I do..... you're the only person I know that owns a V9 Nissan engine. (Or maybe it's a V10 and I just can't see the label on the opposite side.)

 

thank you my man i appreciate that picture but im almost sure i have them correctly plugged but i will check. Im starting to think its going to come down to a grounding issue.

 

coil packs ground with two ring terminals on the front timing cover.

 

thanks for all advice. I have not yet got to work on my car due to snowy freezing weather which is effecting me because i also have a fan issue so its hard to ru up the car because it is too loud and too cold. I would appreciate if you guys have more details on grounding wires. The FSM doesnt give too much about them and it is kind of difficult to find them all especially the ones related to my issue.

 

I don't know what you're talking about. Section PG of the FSM has all the info on ground points you could ever need.

 

It most definitely does not. It shows you all the engine ground wires. The other section of all ground wires just lists " top right of dash" etc.

 

Okay, so SPECIFICALLY, which grounding points are you trying to find, assuming you can't get your hands on a wiring diagram?

 

Hey fellas, i worked on her yesterday and the first thing i checked was the plugs ( #4 and #6 ) and of course they were swapped!! So angry at myself for not doing this first and not checking this before i did all those other things but atrleast now I know my car is in fantastic shape. It has stopped throwing the code and it is running like a beauty. Thank you for all your advice !!! Drift safe my fellow Z members

 

you're welcome...so it had nothing to do with a grounding issue?

go and label all your coils/plugs/wires/etc so you NEVER make this mistake again ...

 

Nope issue was from pure stupidity lol! Thanks again man picture really helped out 💪🏼

 

Don't feel too bad. I push started my Z for 2 days after I put my turbo kit in.

The starter plug I swore I plugged back in was un plugged when I rechecked it. It happens man lol