Whistling noise during engine operation?

This is common when the injector seals go bad here is how to replacement them in the diagrams below. #4 in the diagram below.

REMOVE OR DISCONNECT

NOTE: Use care in removing the fuel injectors to prevent damage to the fuel injector electrical connector pins or the fuel injector nozzles. The fuel injector is an electrical component and should not be immersed in any type of cleaner as damage to the fuel injector may result.

CAUTION: The fuel injector is serviced as a complete assembly only. If the fuel injectors are found to be leaking, the engine oil may be contaminated with fuel.

1. Remove the fuel rail.
2. Remove the fuel injector retaining clips (2).
3. Remove the fuel injectors (3).
4. Remove the fuel injector upper O-Ring (1).
5. Remove the fuel injector lower O-Ring (5).
6. Remove the O-Ring backup (4).

INSTALL OR CONNECT

NOTES:
Fuel injector O-Rings should always be replaced whenever fuel injectors are serviced.
When ordering new fuel injectors, be sure to order the correct injector for the application being serviced. Refer to Application and ID.
The upper and lower fuel injector O-Rings use different part numbers. To identify the correct O-Ring, the upper O-Ring is black and the lower O-Ring is brown. Both O-Rings are the same size but consist of different materials.
The fuel injector lower O-Ring (5) uses a nylon collar, called the O-Ring backup (4), to properly position the O-Ring on the fuel injector. Be sure to reinstall the O-Ring backup, or the sealing O-Ring may move on the fuel injector when installing the fuel rail. If the sealing O-Ring is not seated properly, a vacuum leak is possible and drivability complaints may occur.

1. Coat all new O-Rings with engine oil before installing.
2. Install the fuel injector back up O-Ring (4).
3. Install the fuel injector lower O-Ring (5).
4. Install the fuel injector upper O-Ring (1).
5. Install the fuel injector to the fuel rail (3).
6. Install the fuel injector retaining clips (2).
7. Install the fuel rail.

Check out the diagrams (below). Please let us know if you need anything else to get the problem fixed.