2012 nismo 370z won’t start after gascap change
 

So recently I’ve been having an issue with the “loose gas cap” message. Got tired of it and replaced the cap, got one from autozone to see if maybe that made it go away. Sure enough my temperamental little bag of horses decided not to start. So with some gas added I get her up and running keep in mind it now will not start without pressing the gas. No codes, old cap works fine car starts. New cap, car runs in limp mode and won’t go past 3500. I’m beyond how that can affect anything but I’m not very savvy about gas caps and what they can cause to go wrong. Any advice would be nice before I pay the luxurious 160 dollar diag fee. In my opinion is sounds like a faulty sensor, maybe crank shaft, mass air or canister purge valve?

I'd try another new cap.

1) possibly a generic gas cap that is creating vaccum. Try a replacement OEM cap (these usually should be replaced every 45-50k anyway due to erosion and lack of seal forming)
2) fuel pump has worn itself out due to having to work harder with no tank pressure from failed cap
3) bad MAP (? spitballin here)

The key for me is it will start with pedal depressed, and won't trigger past 3500. That triggers a few red flags in an unusual combination.

It is possible that the combination of poor fuel pressure reg caused the MAF to become off calibration in relation to ECU. You could (just to rule out a few factors) reset the ECU in the 3 step process of resetting ECU op, idle, and throttle setpoints

I recommend using a Nissan OEM replacement gas cap. Other than a bad gas cap sounds like a failed fuel pump if your 370Z will not start.

Or a broken pump assembly top hat.