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Thread: The Micro switch next to the throttle ,has a filter capacitor.

  1. #1
    Member norcimo's Avatar
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    The Micro switch next to the throttle ,has a filter capacitor.

    The Micro switch next to the throttle ,has a filter cap across.

    can someone tell me whats the purposes of this filter?

    when removed, the idle is great...but when its connected... get I the idle hunt...sometimes..

    and cold start issues too..

  2. #2
    Senior Member Bitsyncmaster's Avatar
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    Location:  Leonardtown, MD

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    It should have no effect on idle unless it's a shorted capacitor. It's to reduce the noise caused by turning the power off to the advance solenoid. Without the cap, I got a glitch of the RPM relay priming just by hitting the throttle with the engine off.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  3. #3
    Member norcimo's Avatar
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    Quote Originally Posted by Bitsyncmaster View Post
    It should have no effect on idle unless it's a shorted capacitor. It's to reduce the noise caused by turning the power off to the advance solenoid. Without the cap, I got a glitch of the RPM relay priming just by hitting the throttle with the engine off.
    Well that explains it.

    It was shorted out... I have to find a replacement....what's the value? Cant read it off it...

  4. #4
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by norcimo View Post
    Well that explains it.

    It was shorted out... I have to find a replacement....what's the value? Cant read it off it...
    It's probably a 1 uf or less. Lots of cars never got the cap so it's not critical you even have it.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  5. #5
    Member norcimo's Avatar
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    Quote Originally Posted by Bitsyncmaster View Post
    It's probably a 1 uf or less. Lots of cars never got the cap so it's not critical you even have it.
    I have to replace it, my electrical is going crazy.
    everytime I hit the brakes, the TAC jumps and sometimes the internal lights come up... or if I flash the lights.. same thing.
    though its shorted, the it still filters out... so head to the auto shop and getting an inline DC noise filter.

    Thanks.

  6. #6
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by norcimo View Post
    I have to replace it, my electrical is going crazy.
    everytime I hit the brakes, the TAC jumps and sometimes the internal lights come up... or if I flash the lights.. same thing.
    though its shorted, the it still filters out... so head to the auto shop and getting an inline DC noise filter.

    Thanks.
    I had noise problems when the AC compressor switched off. I put a scope on it and saw >200 volt negative spike. A zener diode attached near the compressor clutch fixed that problem.

    FYI:
    When an inductor (anything with a coil of wire) is depowered, the magnetic field collapses and induces a voltage usually negative. So that induced voltage drives noise in the ground and can upset electronics.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  7. #7
    DMC Midwest - 815.459.6439 DMCMW Dave's Avatar
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    Quote Originally Posted by norcimo View Post
    I have to replace it, my electrical is going crazy.
    everytime I hit the brakes, the TAC jumps and sometimes the internal lights come up... or if I flash the lights.. same thing.
    though its shorted, the it still filters out... so head to the auto shop and getting an inline DC noise filter.

    Thanks.
    That's not from a simple suppression cap. You have another problem, most likely a corroded ground connection or a bad connection at one of the bulkhead colored plugs. Or both.
    Dave S
    DMC Midwest - retired but helping
    dswingle@DeLorean.com

  8. #8
    Member norcimo's Avatar
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    Quote Originally Posted by DMCMW Dave View Post
    That's not from a simple suppression cap. You have another problem, most likely a corroded ground connection or a bad connection at one of the bulkhead colored plugs. Or both.
    Well, I put it back and the problem went away..its been like that for weeks now...works.

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