off throttle flat spot... | FerrariChat

off throttle flat spot...

Discussion in '348/355' started by sirbob, Oct 18, 2006.

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  1. sirbob

    sirbob Formula Junior

    Sep 10, 2004
    343
    South Orange County
    Full Name:
    Jim
    1995, 355B:

    I have a flat spot when I lift off the throttle in any gear. When I shift, as I rev the engine up when I lift off to change gears the engine basicaly goes dead - when I then change the gear and release the clutch the engine abruptly kicks back in - it is impossible to make a smooth shift.

    If I am in the driveway and just rev the engine the first puch up comes up strong and crisp - just as you would expect. If I quickly let off and hit the thottle again it just bubbles and burps until the revs get up to a point when it kicks back in....

    The point at which it kicks back in depends on how high the revs were when I let off... the higher the revs when I let off - the higher the rev before if comes back on the second time.

    Lastly - if I rev then let it return to idle then rev again everything works perfect...

    Any ideas??????????
     
  2. F355Bob

    F355Bob Formula 3

    Throttle position sensor?
     
  3. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
    10,244
    U.S.A.
    Full Name:
    goth
    Yes clean the connections and put some contact grease in the connector. Heck do it to every connector you can :).
     
  4. Llenroc

    Llenroc F1 Veteran
    Rossa Subscribed

    Jun 9, 2004
    5,512
    Colorado
    Full Name:
    Vern
    Do a search it has been discussed earlier. Cam timing, unbalanced bypass screws and throttle plates, anyway do a seach that should answer your question. Regards, Vern
     
  5. sirbob

    sirbob Formula Junior

    Sep 10, 2004
    343
    South Orange County
    Full Name:
    Jim
    Cam timing, unbalanced bypass screws, throttle plates, thottle position sensor.

    Sounds like I have a lot to look at... I'll try to search a few of these - can anybody provide more specific info: ie - shop manual pictures of areas to chack or the right settings etc. ?
     
  6. Llenroc

    Llenroc F1 Veteran
    Rossa Subscribed

    Jun 9, 2004
    5,512
    Colorado
    Full Name:
    Vern
    The shop manual shows the procedure on balancing the air bleeds and the throttle bodies you will need a manometer. I have a 4cylinder motorcycle one that works great. Also shows how to set the TPSs. Cam timing is a little hader to check with engine in the car but the shop manual discuses it too. Reards, vern
     
  7. sirbob

    sirbob Formula Junior

    Sep 10, 2004
    343
    South Orange County
    Full Name:
    Jim
    Vern,

    Thanks for the thoughts..
     
  8. J.P.Sarti

    J.P.Sarti Guest

    May 23, 2005
    2,426
    Check the obvious first, make sure the throttle linkage is working smoothly opening the throttle plates, might remove the intake covers and clean the throttle bodys as they may have gunk in them causing a sticking issue before you get into making any adjustments.
     
  9. sirbob

    sirbob Formula Junior

    Sep 10, 2004
    343
    South Orange County
    Full Name:
    Jim
    Thanks J.P. for your insight...anybody else with ideas, i'm all ears!
     

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