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Why bother doing anything to your Bosch CIS fuel injectors? You might think they are working just fine. Think again! These are the gas fuel injectors used on many engines (but not all) for 1976 to 1993 with the CIS fuel injection system. Kent shows you to recognize if you have CIS fuel injectors and then goes on to show how easy it is to remove the fuel injectors from a 1990 M104 6 cylinder engine. You need to check for air leaks as well as how well the injectors are spraying and sealing. In most cases when you remove the injectors from you engine you will be shocked to see how bad they really are when put to a bench tester.