Engine problem?
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This is a discussion on Engine problem? within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Hi, I just bought a MY07 WRX and live on the equator, i.e. never cold weather (daily ~30C average). In ...

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    Engine problem?

    Hi,

    I just bought a MY07 WRX and live on the equator, i.e. never cold weather (daily ~30C average).

    In the morning, when I start my engine, its idling rpm is around 1500~1600 in neutral gear. However, after a few minutes of driving, the idling rpm drops to around 700 in neutral. Is the high rpm at start normal? I try to let the engine warm up without stepping on the throttle till it drops to around 1250 rpm (takes a couple of minute) before I start driving. Is this pointless?

    Also, there are times when driving and I want to accelerate, I floor the throttle and the engine then "chokes", i.e. it stops firing for a fraction of a second a few times, till I instinctively ease off on the throttle and it fires smoothly then. Can happen from gear 2 up to 5. Am I doing something wrong, e.g. pumping in too much air till ignition does not take place, or is it just my spark plugs need replacement, just too foot heavy or something like that?

    Note I use 97~98 octane gas and I also try to remember to let the engine warm down for a minute in neutral after I park before I switch off the engine. I don't have a turbo timer, just using the countdown timer on my Android cell phone Gives me a chance to check for any messages that came in while I was driving, or look busy doing that, rather than staring into empty space like a nut ;P Is there something I need to check or just some bad driving habit I need to change?

    Any suggestions are welcome.

    Peng

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  3. #2
    Registered User scarmack's Avatar
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    Stock? Mods?
    2012 Limited Black Pearl WRX
    My Build to Destruction
    52 Week Project

  4. #3
    He simply abides. SD_GR's Avatar
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    The idle does not sound abnormal. As for the "choking" I wonder if you are simply describing turbo lag, that is unavoidable. Otherwise I'd suspect a vacuum or boost leak, but so far from what you've said I'd not be too alarmed.

    Unless the car has been driven very hard you can simply park it, turn it off, and get out, no need to cool it down in everyday use.
    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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    Mods, yes!

    Quote Originally Posted by scarmack View Post
    Stock? Mods?
    Hi scarmack

    Sorry it took me a while to get back on this. Yes, there were mods though I don't know what were done. There is an APEXi AVC-R installed too, but more to my story in my reply below to another post.

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    Hi SD_GR,

    Here's the low down on what was the diagnosis when I brought it into the workshop. The head mechanic took a drive in it and turned back after having gone less than half a block. See photo below.



    I had cracks in one of my piston head!! See the circles in red.

    Here's what he told me were the clues to him that something was not right:

    1) Engine block vibrating while idling, kind of like rolling like a boat, with the left and right sides going up and down.
    2) Choking/misfiring as he tried to accelerate, same as I had experienced.
    3) Using a test kit, found loss of compression in one cylinder (#4). 3 had readings of around 120~125 (units?) while the last one had ~70 only.
    4) White smoke coming out of the exhaust at high rev. I probably never noticed that while driving cause I was watching where I was heading up front rather that what's behind me (does anybody who drives a WRX cares what's/who's behind LOL)

    So I had all 4 pistons replaced as a set, plus some other bits. Now it's smooth but am told to run-in the car for a while. Also one of the previous owner did a bit of mod so the chip needs to be reprogrammed to set things right again. Will be getting that done this weekend back at the workshop. As it is, the engine no longer vibrates, is smoother to drive, though I am not driving it hard till I get the engine tuning done this weekend.

    Thought I share my ignorance so that others is aware of such a thing as a cracked piston!

    Cheers
    Peng

  7. #6
    He simply abides. SD_GR's Avatar
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    Argh, sorry to hear!
    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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