If you take them off - SWAP THEM with 2 and 3

 

Ok, will do 👍

 

Update
I think I found my problem 😃, or at least one of them 🙄. I tested each of the injectors after I took them off the engine and cleaned the outside. I tested each of them by hooking them up to a 9v battery. Injectors 1 and 4 didn't click, but 2 and 3 did. Also I sealed the ends in a tube attached to a can of carb cleaner and injectors 2 and 3 worked like they were supposed to (according to a YouTube video), but injector 1 sprayed while not connected to the battery, and without any change while connected. Injector 4 didn't spray at all. If they aren't opening, or are stuck open, do I just need to bite the bullet and buy new ones, or are there any other cheaper options?

 

You can probably buy used or rebuilt. injectors rarely go bad so used may be risk worth taking. You can test them now that you have done it ... Not much to an injector, easy to refurbish so new is not a must.

 

https://www.troublecodes.net/volvo/