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Thread: odd startup occasionally, rpm dip.

  1. #1
    Join Date
    Dec 2018
    Location
    Hudson Valley NY
    Posts
    14
    My Cars
    2008 328i rwd

    odd startup occasionally, rpm dip.

    Hi guys, I purchased my first BMW the other day, a 2008 328i with impeccable maintenance records for all 153,000 miles. Car drives as smooth as can be. Sport package as well, no xdrive.

    I noticed only one thing, over the past few days. Occasionally upon startup, the car will quickly dip in rpm's and then it'll jump back up and high rev for a second or two, almost correcting itself a little, then evens out and idles normally.

    Is this something common? Other than this, I don't notice it any other time, just immediately upon startup, maybe 1 out of 10 times.

    Thoughts?

    Thanks....

  2. #2
    Join Date
    Jul 2011
    Location
    Arlington, VA
    Posts
    9,933
    My Cars
    2018 BMW M240i
    The engine likely has vacuum leaks. Finding all the leaks requires the smoke testing of the intake system. Find a reputable indie shop that specializes in bimmers at www.bimrs.org.

  3. #3
    Join Date
    Sep 2006
    Location
    NW suburban Chicago
    Posts
    16,302
    My Cars
    hiss by my window
    This, in earlier models, is a classic manifestation of failing(ed) VANOS seals.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  4. #4
    Join Date
    Dec 2018
    Location
    Hudson Valley NY
    Posts
    14
    My Cars
    2008 328i rwd
    Ok, thank you. Can you tell me what VANOS is? Sorry, coming from a lifetime of VW Im not yet familiar with all the BMW Tech.

    Update on the symptoms:
    -Still getting mostly normal starts
    -Today upon cold start the dash showed an icon that appeared to be a car on a lift (service??)
    -I got one start with the dip in rpm
    -I got one start where for about 3 seconds, the car felt wobbly at idle, then normal

    Car runs very smooth otherwise, its only upon start up. Cold vs warm start doesnt seem to make a huge impact.

    Does this narrow things down at all? If its VANOS seals, does anyone have a replacement cost ballpark? The car has been serviced to a T by a local private BMW tech, and the previous owner has 4 bmw's and swears by the guy.

    Thanks.

  5. #5
    Join Date
    Jul 2011
    Location
    Arlington, VA
    Posts
    9,933
    My Cars
    2018 BMW M240i
    VANOS is BMW’s version of variable valve timing.

    The first step in diagnosing a problem is to scan the engine computer (DME in BMWspeak) for codes. The Service Engine Soon (SES) light is on only for emissions related codes. Find a reputable indie shop that specializes in bimmers at www.bimrs.org.

  6. #6
    Join Date
    Dec 2018
    Location
    Hudson Valley NY
    Posts
    14
    My Cars
    2008 328i rwd
    Today the car started fine all day long, many times. Then this evening, twice in a row, I started the car and it immediately died. Second attemp, started normal both times. Didnt run even for a second, just started and died. Next attempt was fine. Car runs normal after that. Any suggestions? Anyone experience this before? I only have 1 car so bringing it to a shop is my backup. Thoughts?

  7. #7
    Join Date
    Jul 2011
    Location
    Arlington, VA
    Posts
    9,933
    My Cars
    2018 BMW M240i
    You need to have the engine computer scanned for codes. Period!

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