I have a 2005 Ford Taurus. I got my car checked out at Auto Zone and the code said that the number three cylinder was misfiring. I have changed the oil, had a tune up,( new sparks plugs, fuel and air filter) and changed the ignition coil. Now the car makes a whistling noise when you press on the gas. Now the computer said to check for a vaccum leak, injection fault, and high or low fuel pressure. Also where are the vaccum hoses and how would you begin to find a leak? PLEASE HELP TIRED OF WASTING MONEY.

Test the pressure of the engine of the cylinder 3 if its ok u have to test if there's 12 volt in injector 3 if its ok test if the injector is defected

First off I think it's time for a new mechanic. Doing an oil change and replacing the fuel filter and air filter have nothing to do with a misfire. Spark plugs and ignition coils can cause a misfire, but a good mechanic will test the coil and inspect the plugs instead of just guessing. Your mechanic is guessing and just throwing new parts at the car. A misfire can be caused by (aside from a bad coil or plug) a faulty or clogged fuel injector, spark plug wire, wiring to the injector or a vacuum leak. Since you only have a misfire in one cylinder, and you hear a whistle on acceleration, I would suspect a leak in the intake manifold. Go to a reputable repair shop and have them check the manifold for leaks. You can also check yourself by buying an automotive stethoscope, and moving it around the perimeter of the intake manifold listening for a hissing sound. Or have someone press on the gas while listening for a hiss under the hood.

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