I've searched all of google and on here for a similar issue. I found one thread with the same exact issue but his resolution is not my problem.

I have an 03 350z with an NX EFI Proton plus kit @ 35 shot for testing. The bottle was at 860psi while testing the system. I know the recommended is 900-1000psi but I just wanted to make sure the system is working. After doing a few pulls on the road, I park the car to go eat. When I come back out to start the car, it revs up like normal then the rpms drop and the engine stalls. It only does it after a nitrous run.

I had a similar issue when I first bought the car. Cleaned the throttle body and it was fine, until I started using nitrous. Any ideas fellow z sprayers?

EDIT: Some more information. It is currently not tuned for the nitrous. I have a tune scheduled in a couple of weeks for a 100 shot. This is just a testing phase.

 

Do you spray before or after your MAF?

 

You're freaking your ecu out. Keep it at idle for bit and ecu should relearn.

 

I spray after the MAF. Approx 2-3 in. from throttle body to minimize puddling.

 

I had the same theory. I haven't gotten it tuned yet. I just have the tune for my bolt ons set. Think once I get it tuned, the issue will go away? I just dont want it to be something like a fuel issue.

 

Curious, how long (minutes) was it between the time you sprayed and the time you shut off the car when parked?

 

Around 5-7 minutes from the nitrous run to parking. Then another 30 min eating and starting the car.

 

Sounds like the solenoid isn't sealing perfectly and the car is getting some fuel vapor in the manifold when sitting. Check to see if there's any leakage at the nozzle after using the system.

 

I'm not sure what it was but it only happened on my 30 shot. I bumped up to a 50 shot and it no longer does it.

 

There's no way the jetting change should have affected it, but it shouldn't have done it anyway. With the shot on my nismo there were never any effects on startup or after a run.
Glad it's working well for you though, enjoy the extra power, it really makes the car fun.