456 - Suggestions for Fuel Injectors | FerrariChat

456 - Suggestions for Fuel Injectors

Discussion in '456/550/575' started by Ros456GTA, May 11, 2020.

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  1. Ros456GTA

    Ros456GTA Karting

    Dec 16, 2019
    68
    UK
    Full Name:
    Ros Tagard
    re. GTA 1997


    Looking for suggestions as to replacement fuel injectors.



    thanks
     
  2. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
    37,984
    Clarksville, Tennessee
    Full Name:
    Terry H Phillips
    Too bad to rebuild? That is rare.
     
  3. Ros456GTA

    Ros456GTA Karting

    Dec 16, 2019
    68
    UK
    Full Name:
    Ros Tagard
    I am preempting myself a bit.

    Injectors - I have done the service kit, cleaned and tested them - all seemed good.
    TB - I have calibrated the throttle bodies a-la WSM,

    I have a misfire at tick over that clears as revs pick up.
    I can see that there is a misfire on cyl 4 and 6 and a slightly lower secondary voltage of 4KV instead of the 6.25KV on the others.

    Today
    I will try 2 temp spark leads.
    So that will then leave either the coil pack or a fuel/air issue.

    I'm not familiar with how coil packs degrade/fail - is it common to see 2 outputs to have problems ?
     
  4. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
    37,984
    Clarksville, Tennessee
    Full Name:
    Terry H Phillips
    Not sure if John Cribb ever did his COP conversion for the 5.2 456s, like he has for the 550s. Would likely be cheaper and more reliable over the long run.
     
  5. Qavion

    Qavion F1 World Champ
    Silver Subscribed

    Feb 20, 2015
    11,484
    Sydney
    Full Name:
    Ian Riddell
    By 2 outputs, do you mean two of the three coil pairs in a pack? I'm not sure if the 456 is the same as the 550, but cylinders 4 and 6 are on different coils on the 550. Each coil outputs to two cylinders 1-6, 2-5, 3-4. I'd say it would be unlikely that two would fail (to take out 4&6).

    How hard is it to swap the left and right coilpacks for faultfinding?
     
  6. Ros456GTA

    Ros456GTA Karting

    Dec 16, 2019
    68
    UK
    Full Name:
    Ros Tagard
    Thanks Qavion

    456 should be very similar to a 550.
    Now you mention the cyl pairing of the coil then it seems clear it's not the coil as 1 and 3 are just fine.

    So I will look to spark leads and possibly swap packs left/right, if I run out of ideas.
     
  7. Ros456GTA

    Ros456GTA Karting

    Dec 16, 2019
    68
    UK
    Full Name:
    Ros Tagard
    Solved.

    Now we knew we had an exhaust leak located at the join of the header and cat.
    It was the donut that had crumpled into bits after refitting the exhaust.

    Now here is the funny bit...
    - this was on the header/cat for cyl 1-3.
    - yet it caused a miss fire on cyl 4-6.

    Donuts replaced and all is running fine.
     
  8. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
    37,984
    Clarksville, Tennessee
    Full Name:
    Terry H Phillips
    One reason why it is a good idea to occasionally put a rag over the exhaust pipes on one side while she is running and see if you can hear a leak. Does not work as well when there is some sort of crossover, naturally.
     

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