Vacuum hose to ignition module? | FerrariChat

Vacuum hose to ignition module?

Discussion in 'Boxers/TR/M' started by JohnMH, Jun 30, 2021.

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  1. JohnMH

    JohnMH Formula 3

    Jan 28, 2004
    1,632
    Dubai / Bologna
    #1 JohnMH, Jun 30, 2021
    Can I ask, what would be the effect of disconnecting the vacuum hose from the ignition module on the left side of the engine bay? Does the level of vacuum determine the ignition advance?

    I have my engine out and seem to have forgotten what the hose from the module connects to.
     
  2. carguy

    carguy F1 Rookie

    Oct 30, 2002
    3,402
    Alabama (was Mich.)
    Full Name:
    Jeff
    #2 carguy, Jun 30, 2021
    Hi John....if my memory is right...yes....vacuum does influence the ignition advance. I think the hose goes from the front-left intake plenum to the ignition module.
     
    Steve Magnusson and turbo-joe like this.
  3. JohnMH

    JohnMH Formula 3

    Jan 28, 2004
    1,632
    Dubai / Bologna
    #3 JohnMH, Jun 30, 2021
    Thanks. You would have thought I could have taken a photo.
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,123
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #4 Steve Magnusson, Jun 30, 2021
    See the engine advance curve on page D63 in the TR WSM. With the vacuum line disconnected from the Microplex ECU, A=0, so only ignition curve 1 would always be used.

    They left it out of the graph, but A = the vacuum level in the intake plenum in units of millibar.

    Also, the graph is with the idle thottle micoswitch open. Having the idle microswitch closed retards the whole graph by 4~5 deg IIRC.
     
  5. JohnMH

    JohnMH Formula 3

    Jan 28, 2004
    1,632
    Dubai / Bologna
    #5 JohnMH, Jul 1, 2021
    Thanks. So… where does the other end of the vacuum line plug into?
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,123
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #6 Steve Magnusson, Jul 1, 2021

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