I have a 2004 350z with 26k miles. This is a fully dedicated track car/W2W race car. Here is the situation:

I was running my passenger side PCV open (breather on valve) and getting a lot of blowby at 5k+ RPM is gears 5 and 6, resulting in smoke due to oil seepage on headers and me getting black flagged.

I reconnected the PCV system back to stock, and I do not get any more smoke while driving on the track. After a 30min session, however, I turn off my car and it sits for ~1hr. When I restart the car to get ready for my next session, TONS of smoke bellows out of the car for 3-5 seconds, then trickles out for another ~5min.

If I disconnect the passenger PCV, this issue goes away, but I get bad blowby again at those high RPM under WOT in gears 5/6.

I really have no idea what is causing this because when I am driving on the track, no smoke, just smoke on start up. When the PCV is disconnected, no smoke at startup but smoke while driving.

Thoughts?

 

When you ran the breather on the valve cover, did you use an aftermarket adapter, or did you just put the breather on the OEM PCV valve? If you're using the OEM PCV valve, is it new or does it have some years/miles on it?

It could be something as little as a bad or worn out PCV valve. I ran into a similar smoke issue on startup when I was installing a catch can and using an aftermarket adapter from when I had an open breather. I went back to the original PCV valve but still had some smoke. I replaced the PCV valve with a new OEM valve, and the smoke cleared up. Not sure if that's your problem, but maybe worth a shot?

 

 

OP

Did you ever figure out your issue? I believe I have your old car and I’m experiencing similar mystery smoking at start up but not every time it’s really strange.