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355 throttle break away issue

Discussion in 'Technical Q&A' started by davehelms, Feb 20, 2004.

  1. davehelms

    davehelms F1 Rookie

    Jan 3, 2004
    4,629
    Full Name:
    Dave Helms
    Who was it that was asking for the procedure to repair? I have lost your email.
    Sorry,
    Dave
     
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  3. AZLambo

    AZLambo Formula Junior

    Nov 4, 2003
    506
    Phoenix, AZ
    Full Name:
    Jeff
    Dave,

    I have talked about this issue before and have replaced the circular throttle
    cable pully on top of the engine with the "updated" version. Not much help, though. At low speeds, in first or second gear, I still get that "lurch", no matter how hard I try to "feather on" the throttle.

    I would like to know your "solution".
     
  4. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,055
    Do you have your heal firmly on the black box surrounding the throttle pedal? I found simply having my foot there as a reference point made throttle self modulation less of an issue.
     
  5. BigHead

    BigHead Formula Junior

    Oct 31, 2003
    992
    Outside of Boston
    Full Name:
    Dennis
    I've posted a solution to this problem quite a few times, both here and on Flist. :) I had been incredibly frustrated by this problem. Replaced the throttle pulley thingie on top, cleaned everything, tried everything. Finally replaced the throttle cable itself. The casing was hardened by the way it's routed, to the point it was causing the cable to bind. My mechanic found the same problem in other 355 throttle cables. Each car that had this problem has had it resolved with a new cable, in his experience. For what it's worth.

    vty,

    --Dennis
     
  6. tim355

    tim355 Karting

    Nov 7, 2003
    57
    I have this same issue on my 1995 355 spider. The throttle sticks when completely closed (power off) and when I re-apply power its like I'm trying to overcome some sort of vacum pressure. I took the car into Ferrari of Seattle and they changed the throttle body thingy with a new updated version and re-syncronized the banks ($2000) when I went to pick up the car, the sticky throttle was better but not fixed. FOS wanted another $1200 to clean the throttle bodies and buterfly valves, I declined. I talked to Carlos from Alfa of Tacoma and he has apparently tried to fix this thing on other cars as well with no success. He suggested that I learn to live with it. Carlos says that this issue seems to affect the 1995 only (OBDI computer? 2.7?) and the throttle is smooth in later models. I took the air intakes off myself (3 hours) and cleaned the throttle bodies and buterfly plates of built-up carbon and the throttle seems better but it has not gone away. It is dangerous up here in the Northwest on our winding roads as when you power off prior to hitting the apex of a corner then power on again the car lurches forward and I know someday the rear end is going to come out. A previous thread indicated that the problem is with the idle bypass valve creating too much suction on the butterfly valves and that it takes extra throttle pressure to overcome this pressure. The sensation is that the throttle sticks or is binding. I believe this is the problem as there is no binding at all with the engine off. The thread suggested that by adjusting the idle screws to a more open position it would allow more air into the throttle body at idle. I have been hesitant to do this without a computer. I think I will change the cable as suggested above (although I'm sceptical this will help as the sticking in that case should be noticable with the engine on or off and in my case the throttle is very smooth when the engine is off) and maybe drill a very small hole in each of the butterfly valves to allow more bypass air to enter when power is off. Any suggestions to solve this problem would be very much appreciated.
     
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  8. AZLambo

    AZLambo Formula Junior

    Nov 4, 2003
    506
    Phoenix, AZ
    Full Name:
    Jeff
    I agree with Tim. I have NO "cable-binding" issue with the engine off. I believe this is an "overcoming the vacuum" issue. My car is a '95. Any cure would be appreciated.
     
  9. BigHead

    BigHead Formula Junior

    Oct 31, 2003
    992
    Outside of Boston
    Full Name:
    Dennis
    FWIW, my car (1995) did not exhibit the binding at the throttle with the engine off either. But replacing the cable fixed the problem. It's a CHEAP fix - the cable can be had for less than a hundred bucks, IIRC (~$40?), and it can be changed in about 10 minutes (my mechanic did it in the garage at Watkins Glen with a couple of wrenches).

    And two other cars he fixed that had this problem were later model years.

    Try it. What have you got to lose? You've already spent thousands; this should cost less than a hundred bucks. I have my old cable in hand, and I can *feel* the kink in the sheath where it sticks (and you can see the place where it started to melt).

    Let us know how it works out!

    vty,

    --Dennis
     
  10. Diablo

    Diablo Formula Junior

    Just a reminder, when taking off the Air Intakes...
    Make sure you have properly routed the 4 clamps on each side of the throttle linkage. If you have clearance problems, you might either have no full throttle or in a worst case senario, no throttle return (pedal stuck down!!!)

    Just put them back to the way the factory had set them up.

    Also, I recommend to all to have the two bearings changed on the linkage that the cable attaches to or if that still doesn't help....
    Get the Michelloto linkage assembly..

    Good Luck guys.
     

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