Pulling the injector plug is not a good diagnostic, pulling a plug wire is. All injectors on the B230 fire at once, the fuel vapour stays in the manifold until that cylinder goes to intake stroke. When you remove an injector there is still fuel vapour in the manifold from the other injectors so you will not necessarily see the dramatic change in the running as when you pull a plug wire. How much of a change will depend which injector plug is pulled.

Having said that have you tried swapping the injector plugs from say 4 to 3.

You do not state the problem except to say not running on #4, to me that is a questionable diagnosis. Can you describe what is actually happening.
--
David Hunter