ive always been confused at the signifigance of a occ. wut exactly do these things do and wut do u benefit from having one on ur car? if its that worth it i might get on this one.
the pcv system is inadequate. a long time ago, the epa got their panties in a bunch. motors used to just vent pressurized air into the atmosphere, then the EPA got pissy and said theres oil and s*** in that air blah blah blah. So....the vent was rerouted into the intake manifold, so all the crap that was being vented would be burned in the combustion chambers. now, on a PI car, gasoline mixed with the air will wash away most of the crud that sticks to the walls, us, with DI, do not have that at our disposal and it just cakes and cakes, resulting in the pic i posted. if a chunk of that breaks off, youve got potentially big problems. it also reduces airflow, power, the octane rating (making you prone to KR) etc.
sometimes, depending on conditions the pcv will spray oil instead of oily air directly into the IM where it pools until it all suspends and gets into the cylinder, very bad obviously.
the point of the OCC is to route the pcv vent into the can, where the crud cools, condenses and stays there, while allowing "clean" air to enter the motor.
http://www.saikoumichi.com/OCC_explanation.htm
higher end DI cars, such as the IS-F have a single port injector to prevent this buildup, other cars such as porches actually have the heads cleaned when they go in for service.
