Positive crank case ventilation, while the motor is running the pcv system draws engine block gases & fumes out & burns them along with the air fuel mixture via a hose connected the pcv valve that goes to the intake. Do not rum motor with the oil cap off. If there is suction while the motor is running it is normal.
The engine turns off when the oil cap is removed because the engine is designed to do so. When the oil cap is removed a vacuum leak is created which causes the engine to turn off.
Removing the oil cap with the engine running causes a vacuum leak in the positive crankcase ventilation. This causes too much air to enter the cylinders at once, which results in a stalling engine.
the cap is open
Normally caused by excessive crankcase pressure. A blocked breather or bad piston rings are the likely causes.
The threads are worn and the vibration of the engine causes the oil cap to loosen. Replace the oil cap or try a little teflon tape on the male thread as a temporary fix.
High oil pressure or a faulty oil pressure gauge.
All new cars are Vacuum sensitive. The Oil cap and PCV valve are part of the vaccum system. If you have a vacuum leak this could cause the car to stall out.
Not enough oil pressure and / or the oil channel is plugged
Check for a gasket or O-ring on the cap ( it should have one ), also check crankcase ventilation.
Too much oil, excessive crankcase pressure ( bad piston rings ) or both. pressure causes oil to come the filter tude and capilarity is also a factor. pressure causes oil to come the filter tude and capilarity is also a factor.
Not enough oil.
Compromised oil system, faulty engine oil rifle pressure 1 sensor.