my 2003 350z is running rich. i have the blox plenum spacer, cold air intake, headers, test pipes, and hks replica exhaust. The car runs fine and has alot of power. it was on for a while i pulled off the intake spacer resealed it and it shut off for a little while and now its back on. Any ideas or am i going to need a tune. also on the intake plenum there is a tube out the front sticks out about an inch what is that there was no plug on it since i had the car and no p0175 code but when i put the spacer in i plugged it up. Thanks in advance.

 

That port should be plugged.

Could be an injector that is sticking open.

Either way, with changing that many items on a car it needs a tune. Stock tune is way too rich anyways.