Your car has taken good care of you. It got you where you needed to go when you went to that concert you wanted to see or that date that you had, and now it's time for you to take care of it. Cleaning the fuel injectors on an annual basis is important if you want to keep horsepower, performance of the car and even can extend its life.
So you've decided to clean the fuel injectors. First off you have to open up your car engine and locate the fuel injectors. Before you remove them, make sure that no fuel is going into the engine! This is very important! The best way to do this is to remove the fuel pump and stop the fuel return, which will make sure you won't get solvent into the fuel tank. You can also install tubing that connects the fuel inlet to the fuel outlet called a U-tube.
Remember: fuel lines are pressurized! You wouldn't shoot an LPG tank and you want to exercise severe caution when you work with fuel lines.
Next, you need to hook up a pressurized solvent to the fuel injectors, followed by starting the engine. BE CAREFUL! fuel cleaning solvents are very corrosive and it's best to wear eye and hand protection when you put these on. In addition, cleaning solvent is more flammable than gasoline, so do not smoke or put the solvent near an open flame!
After that, run the solvent through the engine for a few minutes -- then shut off the engine. The solvent may tell you on the bottle exactly how long to run it through for, but around five minutes will be plenty of time to circulate the cleaning solution.
Now reconnect the fuel lines and fuel pump and start the engine. If you notice improvement, then you did it! If you didn't, shut the engine off and try cleaning it again, following all the instructions given. If two attempts fail, then you need to take the car to a mechanic. This is called an off-car cleaning and will cost you about $50.00 and take about one hour for the mechanic to do.
There are still a few things you should do after all this is done. You may need an emission test, so you can find out if the CO and HC levels are okay, also a power balance test will check for weak cylinders (the variations between the cylinders should be less than 10%), and an injector pressure drop test will let you know if the injectors are flowing right or not. Above all, test drive it and make sure that the symptoms are gone.
That's all there is to it! You replaced the fuel injectors and your car is good as new again! Go out there and get that hot date!