Hi Z/G owners,
I am in desperate need of help. i have a a 03 350z base with a vortech that i have been running for a year boost and owned for 4 years. i'm having a P300 code and i have been fixing it for a month and spending over 1000.
*P300 is multiple and random misfiring.
i checked all my ignition and replaced all the weak ones
brand new NGK 1 step colder spark plugs
new alternator
new optima batterey
found oil in my air filter and intercooler piping so i decided to send my supercharger in for a rebuild. i have the SC-V2 trim with 3.33 pulley.
after installing my supercharger i'm still experiencing the same misfiring problem.
seems like the car doesn't have any power.. the idle is a little lower than noraml and can only rev to 4000 rpm. when i drive feels like 50hp car so i left it parked in the house while trying to fix it.
Compression test past by "pep boys"
the mechanic said my car was running to rich.
any ideas?

thank you

 

Start by checking for air leaks after the maf, any leaky intake tubing, gasket etc can cause your car to go rich.

 

are you using SS box?

 

What fuel injectors are you running?

 

I'm using the ss box with Uprev tune and running with stock injectors

 

you should of got rid of the SS box the moment you got tune with uprev. when I was using the SS box I went thought 2 similar situations but mine would revd up to 3k rpms. found out I had to reinstall the software on the SS. Called Split Sec and they did it for me. How much power were you making with the stock injectors?

 

Im making 340hp. down tune due to high mileage engine.. 5psi i think the tech said if my engine was newer i can tune to 360

 

you should check the pulse on your injectors but it would be better if you send them to get clean and flow test.

 

I would do this for sure, you may be over 70% duty cycle on the stock injectors, which would be a bit much.
You should first try to confirm that it is in fact running rich.

 

Why are you running stock injectors with a supercharger and why do you have an SS box with a tune?

 

If you have oil in your air filter and intercooler piping, you more than likely have oil on the maf.

 

I'm running stock injectors because i'm running the FMU from the vortech kit. they install the ss box to my ecu and i guess i had another shop piggybacked with uprev.. not very sure about that. i wish i could run injectors but i'm saving up for my rebuild this year. planning on doing internals, 550cc injectors and upgrade pulley. 185,000miles is too much for any more boost.

 

I would seriously consider cleaning the Maf like meanz said.

I'd say you have a lot of blow-by at this point. Maybe all that blow-by is causing some detonation also.