Surprise! I've gotten more time to work on this car since my side job has taken a back seat.
So, this part is connected to the fuel tank. It's a "roll over" valve. Apparently Nissan thought it was a good idea to let air out if the car rolls over. I think it might also have something to do with if the tank sits too long without the car running, it lets out air.
Anyways, mine was broken, so anytime my car would sit for 2 weeks or so, whenever I would start it, the car would piss gas out the rear. Turns out this part was pissing out along with a fuel hose being cracked and leaking under pressure. NO WONDER MY CAR SMELLED OF FUEL. Finally fixed this and the car still smells rich, but not like pure gas anymore, just rich due to the tune.
So I decided to refresh the car. I got a new thermostat since mine was stuck open and the car could only heat up to 60c, a new shifter boot, and a ISR silicone radiator hose kit as my lower rad hose was cracked and just running gaffer tape over it. It turns out though, that the ISR CA18 kit does not fit!!! The top hose fits ok, could fit better, but the small hose which connects the T pipe to the engine and the lower rad hose both do not fit. The lower rad hose isn't long enough. They must have used a KA rad hose or something in this kit. I'm still looking for a kit to fit. I might just grab the Samco one, as I think that brand has a better reputation.
I got a new o2 sensor for my AEM UEGO wideband. As a warning, DO NOT GET THE STOCK AEM REPLACEMENT. They are complete s*** and will crap out on you. Mine actually lasted quite a while, but died due to very rich environment. That said, I wasn't taking any chances, so I got Bosch 17321. Direct replacement and waaaaaaay cheaper. They're like $60 versus $130.
Here's the old sensor. You can tell my engine was running very very rich.
So, I also got my Power FC Commander screen replaced. I highly recommend talking to FC Hako to get a screen replacement. Way cheaper than buying a new one. Also I had him put in a white colored screen. The screen is bright and looks great. Here is a pic of my interior.
I also stripped my NRG magnetic oil plug! The bolt head broke off. Luckily it took all pressure off the bolt and I could easily get the bolt out the pan without drilling. Thank god. That soft aluminum is very sensitive to torque. I've learned my lesson now! Bought a Cusco magnetic oil plug which is made of a little tougher aluminum, but now I will remember to torque it less.
Finally I was able to replace my fuel pressure regulator (FPR) with a Nismo one. I used two pressure gauges, one mechanical and the other was my interior gauge. Turns out my interior gauge was accurate. I was measuring 42 psi with the engine off. So 6 psi too high of the 36 psi it's supposed to be at. So I put in this Nismo FPR and set it to 36. The car actually runs better now. I had an 11.5 AFR at hot idle on my AEM UEGO. Now it reads 12.0 at hot idle. I always had a suspicion that my car was never tuned correctly due to the FPR weakening over time.