98 306 idle speed wobbles / sunroof rattles
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  1. #1
    Fellow Frogger! young 4 old pug's Avatar
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    Jan 2005
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    Icon4 98 306 idle speed wobbles / sunroof rattles

    it would be fantastic if some one could tell me the origin and solution of my problem.

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    the car is a 5 door 306 xt hatch with only 63000km on the clock. Sometimes, wether it is 5 mins after starting or 30 mins after starting, the idling speed starts to wobble. Normally it idles perfectly at 1000rpm, but sometimes,(doesnt matter what gear you're in including park and neutral) it falters and goes down to 800rpm. it doesnt fix its self until it stalls (or you apply accelerator and start driving) and you are forced to restart the car. Then its fine. Any ideas appreciated as we have only had the car for about 4 months.



    The other problem is with the electric sunroof ( factory fitted ). when the sunroof is closed it rattles. The rattle is a metal sounding one (?) and does not continue to rattle when the roof is popped up or pulled back into the ceiling of the car. (its a 3way sunroof or something like that...)

    thanks again kenny.

  2. #2
    Tadpole
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    Default Idle Wobbles

    Hey Kenny,

    I've got the same model. Your problem sounds almost certainly the stepper motor. I understand very little about what it's for; I think it's used for regulating the idle speed under different conditions. Someone else can tell you more I'm sure.

    What I do know though is that you have the right symptoms, and that mine was replaced just before I bought it (at about 70,000 km's)

    All I can say about the sun roof is that mine is still perfect, so it's maybe not a common problem.

    Cheers,

    Al

  3. #3
    Fellow Frogger! pips's Avatar
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    Default

    The idle motor is exactly that, to let the car idle. This is s separate channel of air from the main line. It basically bypasses the throttle body, as this is completely closed off when your foot is not on the throttle.

    When the throttle body is completely shut off, the idle motor is pushing air into the plenum chamber to allow the engine to keep idling.

    I assume that the ECU keeps tabs on the RPM and adjusts the speed of the idle motor to keep the idle at the specified level.

    I'd take a look at it by removing it and maybe spraying some Carbi Clean (available in aerosol - can form from Supercheap or other "fine" auto parts shops) inside it, blow it out if you can, and re-fit it back into the same spot.

    If this doesn't help, then you'll probably need a new idler motor. Although, saying that, the idler motor might be fine and it might be something else altogether.

    pips
    Ever wonder why Mad Scientist talk to themselves? They know others just wouldn't understand.

    The software said "Windows 98 or better". So I installed Linux.

    1990 405 Mi16

  4. #4
    Fellow Frogger! young 4 old pug's Avatar
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    Default

    thanks, i'll give it a go and get back....

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