Ignition unit squealing! | FerrariChat

Ignition unit squealing!

Discussion in '365 GT4 2+2/400/412' started by David Roberts, Jun 28, 2019.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. David Roberts

    David Roberts Rookie

    Jun 5, 2019
    8
    Sydney Australia
    Full Name:
    David Roberts
    #1 David Roberts, Jun 28, 2019
    Hi again,
    My 1980 400i has no spark at the spark plugs but turns over freely on the starter! The Magnetti Morelli ignition control unit mounted on the underside of the engine bay hood squeals [sounds like a warning tone] when the ignition is turned on!
    There's 12V at the coil, no blown fuses and I checked the distributor and leads. It appears to have a light trigger and blades not points.
    Anyone know a fix?
    I'm going to try another coil in case that's the problem
    Cheers
    David
     
  2. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,603
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    #2 SouthJersey400i, Jun 28, 2019
    Sounds like you are in for a new MSD system, either two 6-cylinder units or more expensive 12 cylinder unit. Search threads.
     
  3. raemin

    raemin Formula 3

    Jan 16, 2007
    1,854
    Lyon (FR)
    Full Name:
    R. Emin
    #3 raemin, Jun 28, 2019
    These units do not like to be jump started, and more generally speaking voltage spikes should be avoided.

    Electronic ignition is usually serviceable, with a bit of luck you can find such specialist nearby, as a last resort have you asked Marelli Services if they could fix it? They advertise a lot their work on mechanical distributors, but on the service page they claim to be able to fix most electronic units also.
     
  4. Newman

    Newman F1 World Champ
    Consultant Owner Professional Ferrari Technician

    Dec 26, 2001
    14,151
    Canada
    Full Name:
    Newman
    #4 Newman, Jun 28, 2019
    They make a squeal when they are powered on. My BB does it too.
     
  5. David Roberts

    David Roberts Rookie

    Jun 5, 2019
    8
    Sydney Australia
    Full Name:
    David Roberts
    #5 David Roberts, Jun 29, 2019
    Cheers! Thanks to all for the feedback!
    I found a Magneti Marelli Dinoplex C Diagnosis and repair link and am working my way through it.
     
  6. Stefan Elshout

    Stefan Elshout Karting

    Dec 1, 2011
    166
    Holland
    #6 Stefan Elshout, Jun 29, 2019
    The AEC104B-660 as used on a 400i uses a magentic sensor instead of points. It is possible that your ignition box still functions but that the magnetic sensor has a problem. It would be best to measure the signal from the sensor with a scope when you crank the engine.
    The ignition boxes itself are known to fail rather often. The electronics are potted in epoxi so repair is not an option.
    I can only assume that by now most of the Marelli boxes have been replaced with an MSD or equivalent unit.
     
  7. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,603
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    #7 SouthJersey400i, Jul 2, 2019
    My Marelli still sparking away! I dread the day it stops.
    Ken
     
  8. David Roberts

    David Roberts Rookie

    Jun 5, 2019
    8
    Sydney Australia
    Full Name:
    David Roberts
    #8 David Roberts, Jul 2, 2019
    Thanks everyone
    There is a 4 pin connector which is revealed by unscrewing the 4 bolts holding the ignition unit ( with the blue Magnetti Marelli sticker on it ) to the base unit containing the potted capacitors and heat sink! This plug had minor corrosion from an over enthusiastic engine bay cleaning! Cleaned the contacts and all’s well.
     
    Schumi likes this.
  9. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,603
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    #9 SouthJersey400i, Jul 2, 2019
    WOW, what a relief! I may just check those contacts as preventative measure.
    Ken
     

Share This Page