Engine Knock (or tapping)

I replaced my sparkplugs, so I had to remove the intake manifold to access the other three plugs. Upon reassembly, my engine now emits this large knocking (or tapping). Could this be brought about my not reassembling the vacuum hoses right? I can't imagine what went wrong where. Could I have dropped a nut in the intake? The sound doesn't seem to be coming dirctky from under the valve cover, but more like towards the middle, but not under the car.

I think you ought to get a life!

I think what you are experiencing is knock retard. Knock retard is created when the PCM and the cylinder and not timed correctly. This happens because the cylinder prematurely fires. It can happen from different things but theyre all to do with the ignition. Since you just replaced them my guess is those plugs are too "hot" for your cylinder. I would make sure they are the right ones or try putting the old ones in and see if it stops.

If its the clicky/tapping sound I know of I've heard it can be the lifters causing the issue. However if it is indeed what Aphix suggested then I will be passing this on to a friend of mine!

Out of curiosity, is it the GDI engine?