How to check leaky injectors n54

[sok7]

Today i’ll be replacing my very leaky valve cover gasket on my 2008 135i. I think I may have leaky injectors, half of them are index 6 half are index 9. Is there a way for me to see if they are leaky when I pull them out?

[jclausen]

I think the last index is at least 13, most of the time the check engine Light is on, engine runs rough, spark plugs are black