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Need help identifying a noise (engine)

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    #1

    Need help identifying a noise (engine)

    I realize that this is an e30 board, but I'm looking for some expert advice, and I was referred here. This is an e46 with 55k miles (2003 325i).

    If you would be so kind as to listen to the following .wav file, I will tell you about it.
    http://home.comcast.net/~ne240sx/325.wav

    This is an underhood sound from 1k rpm to 2k rpm with no load (Park). At ~1600rpm there is a distinct rattle/vibration that continues for about 300rpm then disappears after 2k. This is very recent, we don't have any CEL or power loss in the rev range, however we are very worried. I've heard comments such as "Vanos", "Camshaft angle sensor" and the like. The sound quality is not the best, however, and I'm sorry about that. Any thoughts or suggestions would be excellent.

    TIA
    Tags: None
    #2
    Your shit sounds like it's fucked or in the process of getting that way..

    Honestly, that sound could be alot of things.. and an E46 is alot different from an E30. Take it to the dealership or someone who knows BMWs.

    BTW.. whoever told you to post questions about an E46 in this forum must not read many posts here. I'm surprised a lynch mob has yet to flood this thread.

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      #3
      I can't really determine anything by the sound file, but I would take a quick look at the heat shields near the headers and see if they are loose.

      As said before, take the car to a mechanic familiar with E46's, preferably a dealer IMO.

      One more thing- has the car been in to the dealer for the Bremi coil recall yet? It wouldn't explain the noise, but the bad coils often cause multiple misfires that will cause lots of engine vibration.
      You can check the coils yourself very easily if you want- take the oil cap off, pop off the two round plastic covers on the valve cover, and remove the two 10mm nuts. Pull a coil out and if its all black, you have the defective bremi coils.
      '91 318is
      sigpic

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        #4
        Check that little flapper valve on the intake manifold. It's that reguangular box with a round valve on it right above the rubber air intake boot. Couple of allen or torx screws to pull it out and check. The pin on the plastic door inside likes to pop off and make all kinds of noise.

        Here's a pic of what I'm talking about. That box hanging off the side of the manifold there right behind the dipstick...



        It's not a cam sensor, those just make them misfire a little and stall occasionally, with a CEL.

        Vanos units make a similar noise, but it would be through all the RPMs and get louder in the top end. It would also be more rhythmic/consistant. This is a more random plasticy sound than that.
        Last edited by AdamF 88iS; 01-15-2006, 12:05 AM.
        Adam Fogg- '88 M3

        Common sense- It's the new 'gifted'

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          #5
          Brew, the car has been in for the coils, and thank you for your suggestion.

          Adam, that is fantastic. I will check on that today and let you know. Thank you for your replies, very helpful!

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            #6
            I attempted to remove box, but there is a connector in front of one of the torx bolts, and I didn't want to break anything. I tightened the other bolt back up and voila, the noise is now gone. I wonder if that bolt had wiggled loose, and the whole container was rattling on the mainfold.

            Excellent. Thank you all for your replies!

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              #7
              Originally posted by guidot
              I attempted to remove box, but there is a connector in front of one of the torx bolts, and I didn't want to break anything. I tightened the other bolt back up and voila, the noise is now gone. I wonder if that bolt had wiggled loose, and the whole container was rattling on the mainfold.

              Excellent. Thank you all for your replies!
              I think you'd better check that thing for sure, it could potentially send little bit s of plastic into the motor.
              Adam Fogg- '88 M3

              Common sense- It's the new 'gifted'

              Comment

                #8
                Ya, it came back. I'm going to take a better look at it.

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