2002 WRX rough idle
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This is a discussion on 2002 WRX rough idle within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; 2002 WRX Wagon, stock everything, 94,000 miles, all engine & drive train parts are original. For the past year or ...

  1. #1
    cbf
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    2002 WRX rough idle

    2002 WRX Wagon, stock everything, 94,000 miles, all engine & drive train parts are original.

    For the past year or two, when at a full stop, I can feel the car vibrate while the engine is idling. It happens more when the engine is still cold (not surprising), and it happens more when it's humid out. But even after the engine warms up (reaches about 190F according to my ODB II readout), it still does this a little bit. Enginre RPMs are fairly stable - about 720 RPM warm, a little over 800 while the engine is still warming up.

    Everything else about the car is fine. There's no hesitation when driving, and I feel like I had as much power as the day I bought the car. But I don't remember experiencing these vibrations when the car was younger -- even when the engine was still cold.

    1. Is it anything to be concerned about?

    2. Anyone have any guesses as to likely cause?

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    He simply abides. SD_GR's Avatar
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    If RPMs are stable my initial guess, idle air control valve cleaning, isn't valid I don't think. Suspect MAF dirty, vacuum leak, faulty ground, motor mount, gearbox mount, or nothing.
    WRX Info Links, Courtesy TheJ
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    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
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    Registered User wreckingball man's Avatar
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    Could be your motor mounts like SD said. With bad motor mounts you will experience sloppy shifting, power delivery will be like slightly delayed, and the car can vibrate while you accelerate too.

    A longshot, you said all driveline was original, but I've experienced aftermarket axles vibrate even at idle because most fit so poorly. But you would feel the car shake/vibrate at highway speeds as well if that were the case.


    Is it absolutely *only when you're sitting still?

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    cbf
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    Is it absolutely *only when you're sitting still?

    Interesting question The answer is for the most part, yes, only when standing still. There are no issue at highway speed.

    But .., there is also an issue I've had occasionally when I first start the car in cold weather, I sometimes get bucking and shimmying the first couple of times I go put it in gear (i.e. first gear) from a full stop. When the engine gets warm, that problem goes away. I could often ameliorate/avoid the problem by slowing down my shift into first (i.e. extra smooth clutch release, slower application of power). I had assumed that this was just cold engine stuff, not ready to provide power -- the usual stuff. But perhaps --

    My first car (that was all mine) was a 1978 Honda Accord (yeah, I'm a little older than your average WRX owner). That car had a bucking problem (whole car would shake) sometimes if I applied power too quickly -- in 2nd gear I think. I asked a Honda dealer about it and they essentially said that the motor mounts were under-spec'ed and what I felt was the engine twisting. You see Honda hadn't been making cars for too long and they were still learning (which they did pretty quickly back then).

    Well, I need to find a decent independent mechanic to take a look at this I think.

  6. #5
    He simply abides. SD_GR's Avatar
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    Clutch shudder when cold was not uncommon. Subaru replaced my clutch for that reason. In and of itself it's harmless but annoying.
    WRX Info Links, Courtesy TheJ
    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

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