Open the Precursor door
Open Sez Me
It is also related to a trophy titled Open Sez Me, completing this mission will reward you with a bronze trophy.
After a little practice with the Blue Eco clusters, you will reach a plateau with a large Precursor door crafted out of Precursor metal. Samos will tell you that you need to be charged up with Blue Eco in order to open it.
Walking onto the bridge will trigger a cinematic with Keira detailing the use of Eco Vents. The mission from here is very simple. Jak must collect the Blue Eco and return to the door before the effects wear off, when done so the Blue Eco activates the doorway causing it to open. The Power Cell is right behind it on the other side.