How to tell if wastegate is actually working?

 

if your boost doesn't go to 15+ psi and your engine still runs chances are it still works...

 

well if it didnt work, your turbo wouldnt ever stop making boost, it would just keep building more and more. my wastegate actuator froze on me once a while back. pegged 20psi, luckily my motor survived

 

or if you make no boost it could be stuck open.

 

youd still make boost, it would just be very slow. when my w/g froze shut, i just disconnected the actuator. the exhaust just over powers the w/g port. it makes boost, just really slow. i got 12-14psi at 7500rpm on an 89 turbo.