idle changes when removing oil filler cap?

[rrands1]

I have a 94 3.0 - when I remove the oil filler cap, the engine idle speed changes - is this normal?

-randy

 

[GonOvr]

Yea, it means your engine is sealed. The engine pulls crankcase ventilation through the PCV(passenger side valve cover and the breather(drivers side valve cover) into the intake. By taking the cap off you created a vacuum leak in a sense.

 

[ToyoTech]

idk. i ran cars with no caps before without any issues. it might be that his PCV is plugged

 

[Hyde802]

GonOver is correct.

 

[SUBTEGRAL]

This is a strange thread to me because I've never once in my life removed an oil filler cap while an engine was running.

 

[KidVermicious]

I did. I also tried to put oil in while the engine was running. That made a huge filthy mess, and is how I know GonOver is correct.

 

[Dylan]

idk. i ran cars with no caps before without any issues. it might be that his PCV is plugged

Just wondering, but why would you run cars with no cap? Even if you didn't know it created a vacuum leak, it's still there for a reason.

 

[ToyoTech]

Just wondering, but why would you run cars with no cap? Even if you didn't know it created a vacuum leak, it's still there for a reason.

left the cap on the valve cover and forgot to install. drove around for a few days and it never moved. sometimes i do it at work to see if i need to add more oil so i leave cap of and start the car.