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  1. #1
    Eurodavid
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    Yes | No

    UPDATE on sticky accelerator pedal: need more help

    Ok, Roadfly gurus, I need your brainpower.

    I haven't did a thing to that sticky pedal problem I described last week (it's a slight sticking only initially upon pushing the pedal from its resting starting position---and, no, as I mentioned before, there is no carbon on the inside butterfly plate, and yes, the cable moves freely when detached from the throttle body, also the throttle body plates also move effortlessly with no hitching).

    Anyhow, I don't know why I didn't do this before, but this evening, when I turned the car off, I went ahead and depressed the accelerator pedal a few times, and unbelievably, that momentary hitch/sticking was gone. With the engine off, the pedal, cable and throttle body moves freely and effortlessly, with no hesitating and/or hitching. I then removed the accelerator cable at the throttle body, started the car, and the throttle plate moves freely (when I use my hand), and the pedal and cable (when it is disconnected) moves like it is new, no sticking. but if i put everyhting together, I get the maddening slight sticking when I depress the acclerator pedal from its resting position.

    My question is thus this: what am i facing here? The throttle body plate has zero carbon buildup in it, and when I remove the accelerator cable at the throttle plate, that actual plate it is attached to moves freely (even when the car is running). So what in heck is causing this pedal hitching and/or hesitation if all the components move freely when the car is off, and if all the components move freely when the car is running (the throttle plate and throttle body itself, and also when the cable is detached from the throttle plate, the pedal moves like silk).

    Is my 6 cylinder slowly morphing into an my long-dreamed of 8 cyl and it is creating more, massive suction in the process?? Please, please tell me this is so. If not, where should I look? (Also note: I have tried manually adjusting the accelerator cable in both directions, slack to firm, and the pedal still does it when everything is put together and the car is running.)

    Thanks for any hints and/or tips.

    Eurodavid

    P.S. Here's my accelerator pedal and throttle plate REALOEM diagrams:



    Eurodavid
    1996 e39 528i Throttle Housing Assembly

    1969 e39 528i Accelerator Pedal/Bowden Cable


  2. #2
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    Member No: 4328 jimlev will become famous soon enough jimlev will become famous soon enough jimlev's Avatar
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    I'd disconnect the cable from where it attaches 2(

    linkage under the dash, then pull on it to see if it sticks or if it is smooth. Lube all the bushings on the pedal and linkage to see if it goes away.

  3. #3
    ExAlfa
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    Ditto. I'm thinking pedal wear/bushing sticktion.

    Happy New Year, David.
    I'll be in Grasbrunn for Valentine's Day. I may have travel to Belgium later that week, then skiing either in Innsbruck or with friends in Lausanne. If Belgium works out then maybe we can find a nice pub.

  4. #4
    BigRickMc50
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    Re: UPDATE on sticky accelerator pedal: need more help

    Here's a link to my reply to your beginning post,

  5. #5
    Craig in Canada
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    cable sheath intact?

    I know that mine are breaking down, both the plastic and the metal.

    I just wonder if, under tension, the cable isn't getting hung up in a split in the sheath. In any different configuration it doesn't happen.

    Just a thought. Until you mentioned it as a possible cause, I hadn't heard anyone complaining of worn out accelerator bushings before. If it was a 3 series we'd be able to get polyurethane to put in there as an upgrade :)


  6. #6
    Eurodavid
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    Re: Ditto. I'm thinking pedal wear/bushing sticktion.

    Let me know, before you come, if you make it to Belgium. We'll definitely do something, as there's not much going on (knock on wood) in Jan or Feb. Your gonna die when you see how much snow Europe received in that massive 3 week storm, deep chill. The stuff is still stacked 3 or 4 meters high on the sides of roads, even in Belgium. And Innsbruck or Lausanne, the stacking is reported to be 9, 10 or 11 meters high, otherworldly amounts that they haven't received in over 60 yrs; you are going to be in skiing heaven.

    Eurodavid

  7. #7
    Eurodavid
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    Rick, Craig, Jim, ExAlfa

    Well, I sure wish a simple test would tell me if it was the interior of the cabin or if it was the engine bay, but unfortunately if you read my post, that isn't possible. Nothing matters, it doesn't matter if the car is hot and/or cold or if I detach the cable or not, move it around, which I did and it didn't show me a thing other than the dang cable is smooth as silk (whether car is running and/or not), as is the accelerator pedal (when the car is off, hot and/or cold), and also as is the throttle body plate (hot and/or cold, car off and/or on). The only exhibition of this accelerator pedal stickiness is when the car is running, and everything is together. Nothing, nada, happens otherwise.

    Only thing that seems possible now is what Craig just mentioned, which I hadn't thought of as I slid the cable by hand for testing, doing it with no tension essentially. Also, the only other thing I can think of is along those same lines of the cable being under "tension". I guess it is possible, once the cable is under tension and the car is running (thus the butterfly plate is being sucked closed by the idling of the car), that the tension created is causing any problem and/or wear in the pedal bushings to manifest itself (that is, if it is not a cable sheathing, as he notes, deteriorating, which I hope it isn't). But this seems a long shot, as defective pedal bushings should manifest themselves whether the car is off and/or on, as should the cable, which neither did.

    I'm going to try and get at it all again this weekend, this time completely remove the pedal, the bushings, the spring, maybe even the whole accelerator cable (on the cable, why I do it again I don't know, as it was removed last year, cleaned, and lubed with cable lubricant when the throttle assembly cable bowden oem rubber bushing stops-supports were replaced with aluminum machined bushing stops-supports). I'll clean it all and lube the heck out of everything, and see what happens. Will report back to all of guys what I find after I do all this.


    Thanks for the help/tips! Sure wish I had one of your guy's heated garages, as working outside in the cold is no fun when you are an old man. Those damn HDLs have robbed me of my man cave.................!

    Eurodavid

  8. #8
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    One more joint to check (m)

    Are you sure this joint isn't the problem?

    I'm not sure about the vacuum from the engine being the problem. The vacuum should be trying to pull on 1/2 of the butterfly plate to open the throttle and the other 1/2 of the plate should be trying to keep it closed. So the net effect is the vacuum shouldn't have any influence on it.

  9. #9
    ExAlfa
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    Soft aluminum bushings, maybe?

    I was thinking the spring may have some corrosion that binds a bit when the pedal is first depressed, or maybe the bushings flatted in the rest position. Then you mentioned replacement aluminum bushings so now I wonder whether one of those developed an out of round bore?

  10. #10
    BigRickMc50
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    Re: One more joint to check (m)

    The opening versus closing torques applied to the shaft by the two halves of the butterfly will cancel each other out, but the vacuum will cause the downstream face of the bushings to bear the brunt of the load (and wear).

    I think that maybe the problem lies in a worn achilles tendon due to Euro's extra force applied to the pedal in an effort to make up for a shortage of two cylinders.

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