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Thread: New to ista question.

  1. #1
    Join Date
    Sep 2016
    Location
    NH
    Posts
    119
    My Cars
    98 m3, 00 525i

    New to ista question.

    Been getting a random pop noise that sounds like a cylinder misfire. I decided to check ista to see if it had a misfire live data stream.

    I found the rough idle data stream.

    Appears that cylinder 5 is way different from the other cylinders.

    I swapped spark plugs, and coils to seee if the difference in numbers move from cylinder to cylinder. After doing so, I ran the stream. And nothing changed.

    What is the tough idle actually giving us?

    This has to be an injector issue/ bad compression on cylinder 5?

    Hereís a pic

    upload images

  2. #2
    Join Date
    Jul 2011
    Location
    Arlington, VA
    Posts
    6,718
    My Cars
    2018 BMW M240i
    A misfire can be caused by a myriad of things:
    - bad spark plug
    - bad coil
    - bad connection at the coil
    - bad MOSFET (an electronic part that fires that coil)
    - low compression
    - bad fuel injector
    - leaking fuel injector

    My first step would be to perform a compression check on all cylinders. Any value that is off by 10% or more is a concern.

  3. #3
    Join Date
    Sep 2016
    Location
    NH
    Posts
    119
    My Cars
    98 m3, 00 525i
    Quote Originally Posted by MarcoZandrini View Post
    A misfire can be caused by a myriad of things:
    - bad spark plug
    - bad coil
    - bad connection at the coil
    - bad MOSFET (an electronic part that fires that coil)
    - low compression
    - bad fuel injector
    - leaking fuel injector

    My first step would be to perform a compression check on all cylinders. Any value that is off by 10% or more is a concern.
    Are the numbers normal in the picture ? I have already swapped the plugs and coils. (I highly doubt compression is an issue) But I guess that is the first step.

    Iím not getting any codes for misfires. And I havenít checked misfire counters yet.

    Just to confirm:

    Compression test

    It can be done multiple ways?

    1. Adjusting valvetronic motor at proper angle to open the throttle I assume?
    2. Unplugging injector rail connector.
    3. Turn over the engine a few times to get the gas out.
    4. Remove spark plug + proceed with installing compression tool. And carry out a compression test.
    -moving on to the next cylinder.
    5. Continue on ista menu. Re adjust the valvetronic motor again? And test the cylinder.

    Is this the proper way of doing it?
    Last edited by Bmwpower603; 03-29-2019 at 11:50 AM.

  4. #4
    Join Date
    Mar 2019
    Location
    San Francisco CA
    Posts
    1
    My Cars
    97í Z3 M44, 74í 2002 M10
    Before investing in a comp tester, unless youíve already got one, Iíd suggest remove coil and spark plug from cylinder five and exchanging them with other cylinders.

    ex. take coil out of five and put it in four, remove spark plug from five and put it in three. check again to see if the misfire jumps with either one..

    if it jumps with spark plug then replace spark plugs. If it jumps with coil replace coils. If it doesnít proceed with comp test.

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