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My 355 has a dead spot down low

Discussion in 'Technical Q&A' started by JOW02, Apr 3, 2008.

  1. JOW02

    JOW02 Karting

    Apr 3, 2008
    91
    Brisbane
    Can anyone out there help me with this problem? My 355 has a dead spot down low. When cruising the exhaust note makes a resinating noise and you just push the pedal a fraction and it jerks and takes starts to excellerate. So I have 3 stages through the rev range. Take your foot off the pedal and it makes a nice note. Push the pedal down a fraction and this resination noise starts with no power increase. Push the pedal fraction more the car responds, the exhaust note goes quieter and off you go. Its not that much of a problem but it makes driving slow in traffic jerky, as you go on and off the throttle, and cruising on the highway noisy, as you always have this resinating noise unless your excellerating.

    Has anyone else had this problem?????
     
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  3. PAP 348

    PAP 348 Moderator
    Moderator Owner

    Dec 10, 2005
    86,844
    Mount Isa, Australia
    Full Name:
    Pap
    Welcome to Ferrarichat mate. :):)

    Sounds like your car has a mis-fire I reckon. :):)

    Could be a dead sparkplug lead or sparkplug. ;);)

    Check it out, if you are competent enough? If not, find a good Fcar mechanic in your area and let them have a look.
    If you fill out your profile, it wil make it easy for other Fchatters to help you out in regards to finding a good Fcar mechanic.
     
  4. JOW02

    JOW02 Karting

    Apr 3, 2008
    91
    Brisbane
    Hi PAP, The car has just been serviced so all new plugs etc. It feels like the butterfly values arent in sink with fuel injectors so the butterflies are opening before the ECU is telling the injectors to give it some fuel. Once you push the pedal a little further the fuel is released and all is sweet and she takes off like your normal 355 rocket. Thanks JOW02. P.S. Im located in Brisbane
     
  5. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
    10,244
    U.S.A.
    Full Name:
    goth
    That is what I was thinking. Put some vacuum gauges or manometer on those TBs and sync them up.

    BTW welcome to the forum... :)
     
  6. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    17,269
    USA
    Full Name:
    Hugh G. Rection
    Throttle cable? What year is your car?
     
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  8. Testa

    Testa Rookie

    Mar 28, 2004
    47
    Did you already check the vakuum lines to the fuel pressure regulators ? I had the same problem last year (also after a major service) and found that the vakuum line to the driver side fuel pressure regulator had a leak.
     
  9. ProCoach

    ProCoach F1 Veteran
    Owner

    Sep 15, 2004
    5,439
    VIR Raceway
    Full Name:
    Peter
    Still think PAP's right. Misfire of some sort. That's the most common cause for this drivability problem.
     
  10. JOW02

    JOW02 Karting

    Apr 3, 2008
    91
    Brisbane
    Hi 355SPIDER, Its a late 1995. Its has had the factory throttle linkage cam upgrade already. I think its probally what some of the other guys think. Leaky vacumm line or unbalanced butterflies. That was the direction I was thinking. Thanks JOW02.
     
  11. PAP 348

    PAP 348 Moderator
    Moderator Owner

    Dec 10, 2005
    86,844
    Mount Isa, Australia
    Full Name:
    Pap


    I am still thinking its a mis-fire mate. :):)

    They replaced the spark plugs you said. But did they replace the spark plug leads?? :):)

    Perhaps take it back to the guys that serviced it for some advice? :):)
     
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  13. JOW02

    JOW02 Karting

    Apr 3, 2008
    91
    Brisbane
    Hi PAP 348, How do you check these leads?. Can the service guy I use do this. Can they be tested though out the rev range and under load etc to simulate normal driving condition or will you have to replace them to see if it is the problem. Dont know much about this area. Thanks JOW02
     
  14. UConn Husky

    UConn Husky F1 Rookie

    Nov 11, 2006
    4,416
    CT
    Full Name:
    Jay
    Maybe just sticking butterfly valves? Mine had a nice layer of sticky residue in the throttle bodies before cleaning
     
  15. PAP 348

    PAP 348 Moderator
    Moderator Owner

    Dec 10, 2005
    86,844
    Mount Isa, Australia
    Full Name:
    Pap

    Yes mate, your service guy can check these for you. :):)

    As long as he has an ohm meter. He will have to remove both ends of the spark plug leads and probe the ends with the ohm meter. :):)

    There is also another tool, that looks like a spark plug that has a little aligator clamp on it. You remove the lead and plug in this spark plug and connect it to an earth in the engine bay. Start the car and you can actually see the spark as its firing. If there is no spark, then that paticular lead is ****ed. :):)

    Anywho, it wont take long to check them out. Take it back to your service guy and let him have a look at it mate. :):)
    If I were down there, id sort it out for you myself. :):)
     
  16. PAP 348

    PAP 348 Moderator
    Moderator Owner

    Dec 10, 2005
    86,844
    Mount Isa, Australia
    Full Name:
    Pap

    That sounds fair enough too Jay. :):)

    Did your 355 have this similar sort of issue before you cleaned them? :):)
     

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