Digital 7 Rev Limiter

Discussion in 'PSI Superchargers Tech Questions' started by Flyboy68, Sep 13, 2010.

  1. Flyboy68

    Flyboy68 Member

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    Is there anything that would cause the rev limiter not to work on a MSD Digital 7 7531 box? The max rev and launch rev limiter's aren't working. According to the monitor screen, when the brake is on, it shows the launch limit to be on, but it's not catching. We have the upper limit set at 8000, and the data logger shows we shifted at 8500. Any ideas?

    Josh
     
    #1
    Flyboy68, Sep 13, 2010
  2. Mike Canter

    Mike Canter Top Dragster
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    So what is the application of this Digital 7, is it hooked up to a ProMag? If it is to a Promag then is the yellow plug out of the Digital 7 hooked up to the rev limiter chip plug on the ProMag Electronic points Box? Have you checked those plugs and wiring to the points box? Has it ever worked and if so what did you do to the car right before it stopped working?
     
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    Mike Canter, Sep 13, 2010
  3. Flyboy68

    Flyboy68 Member

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    Mike, this is hooked up to a Promag 44, KB526 blown alky deal. The yellow wires are pluged into the promag 44 points box. I haven't checked those wires yet...I know it's plugged in. I bought the box new, and this is the first year we've ran it. With that said, I don't believe it's ever worked. Atleast we've never went over on RPM to see if it does work.
     
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    Flyboy68, Sep 13, 2010
  4. Flyboy68

    Flyboy68 Member

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    Isn't the rev limit chips just a certain resistance? I should be able to ohm the yellow wires to see if it's setting right.
     
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    Flyboy68, Sep 13, 2010
  5. Mike Canter

    Mike Canter Top Dragster
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    You need to either set the rev limiter to a low rpm such as 4000 or 5000 rpm and start the motor and rev it up and test it. The other way is with a MSD Ignition Tester. If that plug is connected up tight and the wires check out the get a 4000 or 5000 chip and plug it directly into the Electronic Points Box and see if that works. If that works and thewires from the Digital 7 are good then you probaly need to send the 7 back to MSD,
     
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    Mike Canter, Sep 13, 2010

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