run engine hot..Remove the inlet manifold and slacken the bolts that hold the injector in place (only 1 or 2 turns)run the engine and all 4 injectors will hopefully either smoke round the sides of them or bounce up and down a little..The engine may misfire as well(this makes the injectors loose making it easier to remove them)..stop engine once all 4 are moveable remove all injectors and refit new ones but dont forget new sealing rings..oh and torque the injector bolts up when done..