Question on Starting on MAG then switch over to 8973

Discussion in 'PSI Superchargers Tech Questions' started by pentastarrail, Mar 20, 2012.

  1. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    If you read Frank's posts he is NOT using a crank trigger. These "switch over" units are made to take the crank trigger out of the circuit for slow turning motors so they can start. The question I have is if you don't have a crank trigger then what are these "switch over" devices going to switch?
     
    #21
  2. TWD

    TWD Blown alky

    Joined:
    Jan 4, 2008
    Messages:
    99
    Likes Received:
    0
    Switches

    We wired our own switch once. It should be possible to make one to bypass the 8973 for starting purposes, but that's probably not available off the shelf. I'm guessing tach voltage will go up to 60V or so and amp's close to zero, so it's not too spectacular.


     
    #22
  3. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    It seems to me that it would just be easier to fix the problem that is in the wiring of the car. My guess is that the power to the 8973 is probably coming from the same wire or close source as the starter and the voltage is dropping too much for the 8973 so it shuts down or there is just a bad power or ground connection. We know it is NOT the 8973 because it has been swapped out.
     
    #23
    Last edited: Mar 26, 2012
  4. aj481x

    aj481x Member

    Joined:
    Jan 27, 2004
    Messages:
    976
    Likes Received:
    18
    And be sure the 8973 is wired to a capacitor. :)
     
    #24
  5. pentastarrail

    pentastarrail Top Dragster

    Joined:
    Aug 23, 2007
    Messages:
    111
    Likes Received:
    0
    Starting

    That was going to be my next question (capacitor).

    I do NOT have the 8973 (or anything else) connected to an MSD capacitor.

    Since I'm re-wiring the car, should I add one and if so, what MSD components should be connected to it? (just the 8973 ??)

    All my components are wired through my K&R switch panel (or wired direct to switched power if needed).
    (I asked the MSD tech in Chicago if I should have a capacitor, he looked my car over, tested voltages on everything then said no)

    BUT since I'm still fighting this issue I'll pee in a spark plug if it fixes the darn thing.

    I should ADD, this issue JUST started happening the end of last year, before that everything was GREAT.

    Thanks for the input guys.

    Frank
     
    #25
  6. aj481x

    aj481x Member

    Joined:
    Jan 27, 2004
    Messages:
    976
    Likes Received:
    18
    8973 only to capacitor
     
    #26
  7. aj481x

    aj481x Member

    Joined:
    Jan 27, 2004
    Messages:
    976
    Likes Received:
    18
    I may have missed it, does this have a clutch switch to start 8973? trans brake? or?
     
    #27
  8. pentastarrail

    pentastarrail Top Dragster

    Joined:
    Aug 23, 2007
    Messages:
    111
    Likes Received:
    0
    Starting

    Initial 8973 power is from the ignition switch.
    To activate the 8973 (timers, etc) is done by the transbrake.
     
    #28
  9. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    It is a good idea to have a capacitor on the main power wire because they filter out noise spikes and will power the 8973 for a few seconds if power is lost or interrupted but it is not going to fix this problem unless you are having a quick power interruption.
     
    #29

Share This Page