3.0V6 Running like a bag of spanners when oil cap off

[warp_speed]

I just have a quick question. I was changing the oil on my 3.0v6 petrol (ASN engine) when I noticed that when the engine is running and you remove the oil filler cap there is a hiss and the engine struggles to idle. Is this normal?

[adamss24]

If the engine is iddling fine with the cap on then there is nothing to worry about, sometimes the engines need the extra blow by to keep iddling well. I have noticed that too on a few petrol engines...

[warp_speed]

If the engine is iddling fine with the cap on then there is nothing to worry about, sometimes the engines need the extra blow by to keep iddling well. I have noticed that too on a few petrol engines...

Cheers, yeah it works fine when the cap is on. Previous cars I've owned ran fine when the cap was off I was just a bit worried something might be up.