Hi all,
Recently I performed valve adjustment on 11 mdx. To prevent debris going into intake plenum (where u can peek ur intake valves) I put a paper tape and sticked it good. So while hand cranking the engine (with spark plugs installed)to get to my desired cylinder tdc I noticed tape was sucked inwards..(which makes sense) but I saw the air was pushed out a bit as i saw tape making an outward bubble. I saw all six cylinders made the in and out ward air push behavior.

Is this normal what I noticed of air being pushed out? I shined a flash light at valve base and i didn’t see any carbon there.