I have an 03' z, mod list includes nismo s tune catback, kinetix plenum , injen short ram intake and a lightweight pully.

For the past couple months (I'm stupid for not getting it taken care of asap) my car's been giving me a p0171 and p0300. I tried cleaning the MAF and replaced the spark plugs with iridium plugs, it cleared the p0300, i still had the p0171. Now, I'm getting P0171, P0300, and P0302 (cylinder 2 misfire) and i'm not sure what to test for. I've searched the forum and I saw that replacing the coil pack may fix the misfire on the specific cylinder, and I may have a vacuum leak (which i haven't tested for yet) that is causing the p0171.


My question is: while i'm in the middle of doing all this work, what parts will i have access to while replacing and fixing my car in its current state? I ask because I want to know what I can upgrade while i'm doing this job? Also any advice on the issues I'm getting would be appreciated

 

You probably have a vac leak, injector isnt working and or you spark/coil pack is bad.

As far as access, nothing really asside from the plugs, coils, fuel rail, and intake mani. You're not really getting into the motor at this point.

 

When you refuel, which octane are you putting in the Z; Regular, Plus or Supreme??

 

I usually use 91 octane from Arco, lately I've been filling 91 from Chevron just to get the quality stuff in my car. I've used a full big bottle of that injector cleaning stuff over the course of three fillups to see if it would help, and while it did seem to help right after I used it, the CEL would come back on for P0171. I also forgot to mention in the OP, which i will edit right now, that occasionally the car will smell HEAVILY like unburned gas