vacuum in engine

car is a 97 e36 318is. there is like a vacuum in the engine, there is like blowing noise coming in engine bay when car is turned on and the car isnt idling correct. when i open the oil filler cap the noise stops and its idling properly. if i put the oil filler cap back on again you can feel the suction.

also got a code 3e misfire with the diagnostics. cant find anything on code 3e in google :/

any help appreciated. thanks!

CCV valve is gone

Thanks very much man!! Replaced that already when i bought the car but changed it with a used one from my old bmw. Will buy new one this time.