I used to be a Honda guy and have in my opinion relatively decent mechanical knowledge, now I have a Veloster turbo, but my girlfriend has an 05 automatic 350z and I’ve been trying to help fix some issues for her but I’ve hit a roadblock. It literally seems like a vapor lock issue from the symptoms but I didn’t really think that was a thing on fuel injected cars.

Her car starts perfectly fine cold, but has an intermittent issue when warm starting. After running for a couple hours tonight it was shut off and restarted a couple minutes later and wouldn’t run, turns over and acts like it’s firing up but does nothing, on second attempt it turns over and tries to fire up, but sputters horrendously and then dies. Giving it gas while it’s happening does nothing sometimes, other times it does the moment I press in the throttle. Usually by the third or fourth try it will start and stay running but sounds like it’s misfiring pretty badly. After I reach that point if I shut it off and restart it again it’ll run fine. I’ve been chasing this issue for a couple of days now it’s been happening for about a week. I have changed both cam position sensors this morning with new Hitachi units from Rockauto (I know they’re not OEM Nissan but I trust hitachi to make electronic) and it seemed alright at first but had the same issue again tonight. I also blasted some cleaner through the throttle body while I had it off doing the cam sensors. I considered a failing relay due to heat and swapped over the headlight high beam relay for the fuel pump relay and it started up then sputtered again so not that. Still no luck. The car does not throw any codes other than for cat efficiency, which made me consider a clogged cat but that makes no sense, I feel that would cause it to be down on power and cause consistent starting issues not intermittent warm ones, and her car will still absolutely destroy my Veloster from a stop. I have a set of Kinetix High flow cats coming in the mail that I ordered as a present for her and also to get rid of her check engine light but I really don’t think that’ll fix her issue. My next guesses are fuel pump or crank position sensor from the research I’ve done. Does anyone have any input on a similar issue?