Thats good it means your breather system is not blocked, and crank case pressure is being fed back into the metering head like its suposed to.
cris4rst I think your a bit confused mate!? Unless he is EFi the car should cut out if you remove the oil filler cap because that creates a giant air leak preventing the flap in the metering head from being sucked down and giving the car any fuel!

If you whip the oil filler cap off and put your hand over it you should feel suction, if you feel pressure then yeah that indicates possible heavy piston ring/Bore wear etc...