Q: where is pcv valve located on 2000 BMW 740iL

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
smokes when i start it after sitting for long period of time (1 hr or more)
(1) Answer
Is it just a puff of smoke, or continues to smoke while you are driving it?
When you remove the intake hose, carefully open the throttle plate (with the ignition off!), do you see lots of oil inside of the intake manifold? Beside the PCV valve the valve stem seals could also leak.
The breather valve (PCV) is located at the back of the intake manifold and it isn't the usual ball and spring type of valve with a breather hose attached to it, but a big plate with a diaphragm inside - bolted to the manifold.
The best way to service it:
-remove the intake manifold so you get a better access to the breather valve and to the breather pipe under the intake.
-replace the valve and the O-rings of the vent pipe (they needs to be slightly coated with oil), check the pipe and clean or replace it if necessary.
-the intake manifold gaskets also need to be replaced.