Ticking sound from my M42 [Youtube video]

[rokkas]

Hello everyone,

Recently (since it's summer here and I started driving with windows down) I noticed this weird ticking sound coming from my engine.

With performance chip installed, the sound was there all the time and it didn't seem to change with increased RPMs. As soon as I put o2 relay back, it just started to tick faster. This is the sound I had with a chip installed and o2 relay removed - https://youtu.be/W7yPRWBXm0E

So as soon as I noticed this ticking, I installed the stock chip back and thought that the sound disappeared, but I keep hearing it sometimes after driving and it goes away after a few secs of idling.

I'm currently using 5w40 fully synthetic oil (on the dipstick it is a bit above the middle between min and max). Just replaced all spark plugs as well as valve cover gasket, since one plug was leaking.

This is my first car and I'm lost on what could be making this sound. Please help.