You can always connect a 9v battery to each injector independently or have them sent off for sonically cleaning which is a smart thing to do regardless. Mr. Injector does a fine service. Iridium plugs are good to have as well. Spray aerosol injector cleaner through them backwards from a fresh can. Then compressed air. Simple. Frankly sending them off is the proper method so they can be tested and visualized with a graph. Its all apart of the process, no worries. Step by step.