How to test your fuel injectors
Check The Injector Tips
See if the fuel is leaking from the tip or it is clogged with dirt or carbon by simply rubbing your finger over it. It is one of the most effective methods to find the bad injectors.
You may use a flow meter to check the rate of flow of fuel to your engine. If the injectors are clogged than it will have lower flow rate. You must cleaning it to improve the flow rate and performance of the engine.
Check Engine Idle
Try to start the car engine and let it run about two minutes so that the idle stabilizes. Then open the hood and unplug the connector from one of the injectors. And see if the engine idle is worse or the same. Repeat the same process with all the injectors inside your car. If it is worse than this injector is dead.
Check Coil Resistance
Set your multimeter to ohm settings. Now remove the electrical connector from one of the injectors. Attach the leads of multimeter to the metal prongs of the injector. Take the reading. Repeat the same for all the injectors. If the reading of one of the injectors is too high or too low compared to the reading of the rest of the injectors, than it is faulty.
See the Spray pattern
Open the hood and place a bright LED light over the spray pattern. Make sure that the spray pattern is regular. A poor spray pattern will indicate that your injectors are dirty and less fuel is entering your engine.