Frequency Valve question | FerrariChat

Frequency Valve question

Discussion in 'Mondial' started by bigeasy, Nov 23, 2016.

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  1. bigeasy

    bigeasy Formula Junior

    Dec 31, 2012
    368
    Is the Freq. valve "supposed" to be buzzing only when the engine is running? or should it buzz when the key is in the on position as well. Replaced the relay a couple years back, but getting the popping / sight backfire back again on startup. My exhaust is louder then stock and really can't determine if it buzzing and I don't really feel and vibration. Didn't see any posts that helped answer my question.

    Thanks,

    Happy Thanksgiving to all.
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,038
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    It buzzes only when the fuel pump is running (so, on a stock system, it will buzz either during starter motor cranking or when the engine is running, but not with just the key "on" when the engine isn't running). Easiest to unplug the safety switch then turn the key "on" = should run the fuel pump without the engine running.
     
  3. bigeasy

    bigeasy Formula Junior

    Dec 31, 2012
    368
    Thanks Steve, forgot about the safety switch. Unplugged the switch on the fuel distributor and turned the Key to the first position and it indeed Buzzed. Thanks, Found that the two wire connector was very loose, to the point it came off with little to no effort. Installed a new connector.

    To check the freq. valve relay, do you simply check for voltage on the two wires going from the relay to the valve? I have one of the newer fused protection relays, just wanting to make sure that end of the fuel process was in check.

    Thanks Again.
     
  4. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    3,859
    If you have an aftermarket exhaust, you may need to richen the mixture in order to compensate for the reduced back pressure. A lean condition can cause a backfire. Also check for vacuum leaks.
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,038
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #5 Steve Magnusson, Nov 23, 2016
    Last edited: Nov 23, 2016
    No, the protection relay sends +12V power to run the injection ECU which then sends a ~50% duty cycle signal to the FV. If the FV is buzzing that confirms the injection ECU is trying to run the FV so it's almost a certainty that the protection relay is OK and doing what it should.

    So you went from the early 5-pin, internal 10A fuse protection relay to the later 4-pin, external 10A fuse protection relay? Did you do the rewiring? Or has your car always had the later 4-pin style?
     
  6. Archer911

    Archer911 Formula Junior

    Sep 26, 2016
    907
    New England
    Full Name:
    Tim
     
  7. bigeasy

    bigeasy Formula Junior

    Dec 31, 2012
    368
    Did the rewiring to four pin for the fused P.R. with your assistance, (thank you.) maybe 2 years ago.

    Not surprised it is still working well.
     

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