Look at the differences and see if we can better understand the Nissan four wheel drive and all wheel drive systems, how to tell them apart and, most importantly, where to look when something goes wrong.
The 9A1 architecture is the current engine Porsche uses in their Cayman/991/GT3 & 4 platforms. It encompasses many models but generally refers to model years 2009 through the current 2018 models, although designations now also include the 9A2.
Vehicle emissions control devices have been in use for more than half a century. The crankcase ventilation system was one of the first emissions systems used on cars.