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Throttle sticking at WOT

Discussion in '456/550/575' started by Toddrab13, Sep 12, 2018.

  1. Must see the interview we did with Piero Ferrari in Maranello! https://www.ferrarichat.com/forum/news/297
  1. Toddrab13

    Toddrab13 Karting

    Jul 10, 2011
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    Michigan
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    Todd
    After having the intake manifold off, I am experiencing intermittent throttle sticking at WOT. There is nothing obstructing either side though I realize I must have caused the issue as it didn't happen before it was a part. Any ideas what could be causing it?

    On a side note, everything is back together and I have zero error codes or idiot lights for the first time since I bought the car! It has been one thing after another this summer, hopefully I can finally enjoy driving it! Many thanks to everyone who helped me, I couldn't have done it alone.

    I did notice as I was changing the thermo coupler today that I still have the original 550 engine mounts... Not sure that is something I want to get into but I imagine it should be changed sooner than later. Can't win them all.

    -Todd
     
  2. Cribbj

    Cribbj Formula 3
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    Todd, luckily the 550 has mechanical throttle actuation. Just follow the system from the pedal up to the bellcrank on the left side, then on to the left to right side cabling and find where it's binding...... Considering it's sticking at WOT, it's probably best to do this with the engine off :)
     
  3. Korr

    Korr F1 World Champ
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    Stew D Baker
    I don't have a solution, but I cannot think of a more excitement inducing malfunction, either.
     
  4. Toddrab13

    Toddrab13 Karting

    Jul 10, 2011
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    Thanks John, will do. Didn't find anything obvious so I just sprayed a little wd-40. Hopefully that will solve the problem. Test drive still to follow.

    Hopefully my test drive doesn't have too much excitement... Lol
     
  5. fatbillybob

    fatbillybob F1 World Champ
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    Aug 10, 2002
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    How about some very clear pics of your throttle cable system? You have something wrong. There should be zero sticking throttles. That's just plain dangerous and unsafe
     
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  6. AVIMAX

    AVIMAX Formula Junior

    Aug 5, 2014
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    Ryan
    Something else to consider while you are sorting this problem out, it might be time for a new throttle cable between the two sides. When my car was in at an independent mechanic for a new windshield, he commented to me that my accelerator pedal is a bit stiff. I didn't find it all that bad, and always figured that was just how it was. I decided to change the cable anyways since the plastic covering was starting to crack. What a difference! I compared the old and new cables off the car, and the sliding action felt the same to in my hands, but on the car it is night and day. The accelerator pedal is so much lighter now. Funny how the smallest things can make a car feel so different. The lighter pedal makes it the engine much more responsive. Had to reprogram my brain to be able to drive smoothly again.
     
  7. Toddrab13

    Toddrab13 Karting

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    Todd
  8. fatbillybob

    fatbillybob F1 World Champ
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    When I get back home I will look at my car for comparison.
     
  9. AVIMAX

    AVIMAX Formula Junior

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    Looks normal to me. Double check (I'm sure you did already) that there isn't a cable or hose running under the throttle bodies that the butterfly lever may be catching on sometimes.
     
  10. fatbillybob

    fatbillybob F1 World Champ
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    OK i looked at my car and what I can see of yours looks the same. I would look very carefully at the bell crank area that you can't see in the pics for any area that can be binding. The throttle cable is kind of sprung. It is a weird thing with cable in a tube which is made of other longitudinal wires wrapped in plastic cladding. I don't think that is a good design from a stichion standpoint but it is ferrari. You possibly bind the cable if you tooth the throttles off the car during your major as one piece connected. Then you put the drivers side on then the passenger and if it is twisted you will see the bind at the passenger side terminal throttle cable socket onto the throttle ball cocked hard like 90 degrees and you can feel it when you twist it in your hand. Ideally that would be passive so the socket can swivel easily over the ball. Then it is possible that a lack of lube can foul the cable inside. Your pic shows that kind of dry surface corrosion that is a high friction surface...but I have seen worse. You want to make sure the return spring in on the throttle right and working well because that's all you got to push the cable back in the housing and to push the pedal back. Then I would check the throttle to the pedal part individually disconnecting at the driver's socket to the throttle ball. There is plenty to foul there dirt etc. If something isn't obvious...If it was me I would remove the throttles so I could 100% evaluate the return springs. I would remove the cable from throttles and check for free motion maybe clean and lube it. Then I would go after the throttle to pedal cable part cleaning and lubing it.
     
  11. Cribbj

    Cribbj Formula 3
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    If you remove the cable assembly to check for stichion (t/m by FBB) be careful not to make any adjustments to its length, otherwise when you put it back on, the left and right side T/B's will no longer be in sync, and they're a bear to resync unless you have an SD2 or similar. It'll throw codes such as misfire, etc. and will generally run like cr*p.
     
  12. Motob

    Motob Formula 3
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    Nov 11, 2003
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    Brian Brown
    The clamp for the right side throttle body boot looks like it is loose and could be fouling the throttle mechanism. Don't drive the car until you figure out the cause of the sticking throttle, Very dangerous!!!
     
  13. Toddrab13

    Toddrab13 Karting

    Jul 10, 2011
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    Todd
    Thanks for all the help guys! Here is where I am at, and unfortunately a test drive seems to be the only way to check if things are sorted...

    -I took the cable off of both throttle bodies and actuated both linkages by hand and there is no hang up and no interference

    -Both the 360 cable and the throttle cable move freely

    -Niether cable is twisted, that would definitely cause an issue and seemed rather difficult to accomplish

    -The cable to the pedal has no interference and moves freely

    -There are no mats or carpet interface inside the car

    -I cleaned and lubricanted the ball joint on the pass side and did the same on the driver

    -Everything moves freely and never binds in anyway when I move the system by hand.

    I want to point out that this is a very intermittent problem that only appears to happen at high rpm and under heavy throttle but only sometimes. After cleaning and lubricating the joints, I went for a test drive and nothing hung up. I thought I had it fixed yesterday too but after 30 miles or so I had it stick. I wish I was more convinced I have fixed this for good...

    Great catch Brian! The clamp was loose. Nothing was interfering but that was an amazing catch from a photo!
     
  14. Motob

    Motob Formula 3
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    Did it stick after you tightened the clamp up in the proper position?
     
  15. Toddrab13

    Toddrab13 Karting

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    No it has not. Maybe it's good... I don't think the clamp was causing interference but I guess I don't know exactly what is taking place under hard acceleration.
     
  16. Motob

    Motob Formula 3
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    #16 Motob, Sep 14, 2018
    Last edited: Sep 14, 2018
    Your car is not the first that I have seen with this problem. When that clamp is loose the head drops down and catches the mechanism of the right throttle body, jamming it at wide open throttle.
    It also why the throttle sticks intermittently, as the clamp has to be in just the right position to jam the throttle open. Anything else, like a binding cable would happen every time you went to wide open throttle and not be so infrequent.
    Try loosening the clamp up and rotating the head down to the bottom and see how it can get caught in the mechanism.
    I am 100% certain that this was your issue.
     
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  17. fatbillybob

    fatbillybob F1 World Champ
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    Thanks for your posts Brian...you may be saving lives!
     
  18. Toddrab13

    Toddrab13 Karting

    Jul 10, 2011
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    Yes Brian, thank you! I will check that when I get back in the garage Sunday and confirm that the clamp is not only tight but in the proper position.
     
  19. milessl500

    milessl500 Rookie

    Jun 2, 2011
    13
    Confolens France
    Could it be that the the plate within the throttle e body is sticking on the side wall of the throttle body on WOT . ie the varnish from the rather poor gas used today, needs cleaning. easy to check and clean
     
  20. Toddrab13

    Toddrab13 Karting

    Jul 10, 2011
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    Brian, you were 100% correct. The clamp in the position in the photos was a potential interference and when I tightened it, I raised it with out thinking. I think the problem is fixed. Thanks Brian!

    I will definitely clean the throttle bodies just in case.
     
  21. Motob

    Motob Formula 3
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    Good to hear. It can't hurt to clean the throttle bodies. I always to it when I have the boots off, but I can't imagine the amount of varnish/carbon in a throttle body that would cause it to stick.
    I could see varnish causing the plate to stick just off of idle when the plate is barely cracked open, but at full throttle the plate is 90 degrees to the bore, nowhere near any varnish deposits. Spring return pressure is at its highest in this position, so no amount of varnish is going to cause it to jam at full throttle.
    I think that you have your problem fixed.
     
  22. F456M

    F456M Formula 3

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    I experienced the same during testing of a 550 for sale. Quite interesting!
     

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