So last weekend i changed out my spark plugs and ran into this non stock looking valve. Its vacuum and ties into a lower vacuum rail that leads to the brake booster. The upper part of the line goes to the intake plenum just before the throttle body. It seems stock the house would be one piece without the valve. Any ideas what its for?
Thanks!

 

Crap, sorry mods. Can you please move this to the 350 area?

 

What's it do when you turn it? Brakes stop working?

 

Looks like a motordyne coolant control valve.

 

It's part of the intake plenum spacer mod for 350z by motordyne. It's for when the cold weather comes you open it up so that warm air warms up the throttle body, and in the summer you block it off so that warm air doesn't keep warming up the throttle body when it is already warm.

 

Thanks Milton! I picked up this 03' Touring in Jan. It's had some mods done per the previous owner (light pullys, flywheel, 4.83 final drive, springs and the plenum spacer) but not exactly sure what brands. The plentum spacer is one of them and thanks to you I now know it's by Motordyne.