Vader action chain….

[Boba Fettish]

Can vader spend force to take a second action in his activation phase - then if one of those was passive sensors  take an action before he engages due to the passive sensors charge being inactive - and then spend an additional force for another action.  

[Tim H]

Darth Vader (Tie Advanced X1 Pilot)'s ability can trigger after you perform any action. This includes after performing actions on upgrade cards such as Passive Sensors, and the calculate or lock action granted by Passive Sensors, if it's charge is inactive before you engage.

So yes Vader could do the following
1) During their perform action step, do the Passive Sensors action to spend it's charge. This would trigger Vader's ability allowing him to spend a force to perform an action.
2) Spend a force to perform a focus action (Vader's ability).
3) Before Vader engages, the charge for passive sensors is inactive, so you may perform a calculate or lock action. This would trigger Vader's ability allowing him to spend a force to perform an action.
4) Spend a force to Perform a roll action (Vader's ability).