All you could do is make a wild guess from what we have been told so far.

Guys, there are a hundred moving parts under the hood, to say it is ticking doesn't help...

Does it go away once the engine has warmed up? Is the rate of ticking related to the rpm?

Could be the exhaust manifold leaking, that usually goes away when warm unless it has been doing it for a long time.

Could be a spark plug getting ready to blow out

Could just be the typical cold engine noise most of these engines make.

Fuel injectors are apretty soft tick, usually not heard with the hood closed.

Timing chain tensioners could be bad leading to several different noises.

So short of someone like Mel offering to come take a listen, you are going to have to help narrow it down on your end before anybody can be much help here.