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328 Stereo Trouble

Discussion in 'Technical Q&A' started by PMDDMD, Mar 20, 2005.

  1. PMDDMD

    PMDDMD Formula Junior

    Apr 1, 2004
    362
    I have recenly been hearing a lot of engine noise when operating the stereo in FM mode. The CD player works normally, but when switched back to FM, it plays normally for a few seconds, then the engine noise kicks in. I've had the entire unit out to check connections, grounding, and even checked the wiring to the antenna for connection issues. Anyone have any experience with this or do I just need a new stereo system?
     
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  3. DGS

    DGS Four Time F1 World Champ
    Rossa Subscribed

    May 27, 2003
    41,988
    MidTN
    Full Name:
    DGS
    Argh. Check the archives. Some 3x8s use resistor plugs, others use resistor extenders. Some red extenders are resistor types, some aren't. I don't recall the matrix of which years had what, but it should be in the archives. The resistor in the ignition helps cut down on radio interference. (I think I remember that the 328 uses non-resistor extenders and resistor plugs -- but don't go by my memory, it's not what it usta was.)
     
  4. shifty308

    shifty308 Karting

    Aug 7, 2004
    75
    coulterville ca
    Full Name:
    steven schiffler
    you could try plugging a different antenna in just to be sure your current one is good, i used to do stereo install and have seen antennas which look good be bad, just remember to ground it. if it is not that or plugs,wires. it is probably internal in radio.
     
  5. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    17,177
    USA
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    Hugh G. Rection
    Agree with Steven, that was the problem with my 328 radio interference problems, bad antenna! Not sure what was going on with the original one, but a new one fixed it.
     
  6. gdbsti

    gdbsti Formula Junior

    Oct 10, 2004
    283
    Nor Cal
    Full Name:
    Bruce
    Another antenna as Steven noted grounding it at the antenna base sounds like a good starting point to me too.

    Failing that, does it sound like a whirr/whine/turbo noise or a ticking? Turbo like noise indicates alternator whine (Rectifier or stator may have a problem) and ticking indicates more of an igniton/HV symptom.

    You can discount the alternator by disconnecting it and running the car. (the car won't charge briefly)

    How long ago did the noise start? Was it a gradual increase or happen all of a sudden?
     
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  8. PMDDMD

    PMDDMD Formula Junior

    Apr 1, 2004
    362
    The sound is a revving sound definitely in sync with the sparks...hit the gas and the revving speeds up. I noticed it in the late fall just before putting the car in storage. It just started one day. It's interesting, though, that when the stereo is first turned on, it works fine. After about 30 seconds, the revving kicks in. When I had the sysem apart last fall I did notice that it would go away when the antenna touched the body metal, but the ground was never disconnected. This, combined with your feedback is pointing me in the direction of a bad antenna...I'm going to give your suggestions a try. I'll post the results.

    Thanks!
     
  9. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
    Rossa Subscribed Owner

    May 4, 2001
    31,328
    Birmingham, AL
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    Tommy
    How does an antenna go bad?
     
  10. gdbsti

    gdbsti Formula Junior

    Oct 10, 2004
    283
    Nor Cal
    Full Name:
    Bruce
    Broken core wire (it's very small gauge) and hi resistance in the caoxial lead where it connects to the stainless antenna generally cause antennas to go bad. The connections are crimped as they can't be soldered, and with the water getting into the aeriel body, they corrrode internally a lot. (Ever noticed electric aeriels have drain holes in the bottom of the body.)
    The stainless sections of an antenna don't go bad but can build up resistance between them if they are dirty or have too much oil on them.
     
  11. PMDDMD

    PMDDMD Formula Junior

    Apr 1, 2004
    362
    I nearly forgot, but around the time I noticed the engine noise in the radio, the switch in the console which extends and retracts the antenna began to work intermittantly..I have a new one already but have not installed it yet. Any possible connection to the engine noise or merely coincidence?
     
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  13. gdbsti

    gdbsti Formula Junior

    Oct 10, 2004
    283
    Nor Cal
    Full Name:
    Bruce
    Did you electrically diagnose a faulty switch or just get one because it appeared mechanically broken?
    Sounds like a possible ground issue.
     
  14. Bob5013

    Bob5013 Rookie

    Mar 26, 2005
    42
    Syracuse, NY
    Full Name:
    Bob Pakan
    Yep, first thing to do is check all your grounds, especially the ground to the stereo unit itself. Antenna and antenna cable and the next things to check. Make sure all the grounds are good. Usually plug noise does not bleed through to the FM band (frequency modulation verses AM (amplitude modulation - which is effected by plug noise)). Wouldn't hurt to check the plugs and the wires to make sure all meet spec. The only other thing that comes to mind might be that the FM receive citcuit components have finally aged to a point that after a few seconds of "warm-up", they drift slightly and allow some of the interference to pass through.

    Check the easy stuff first and as a last resort try temporarily swapping in another unit. Good luck!
     

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