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  1. #1
    Registered Member One Ring
    Join Date
    Dec 05 2016
    AZ Member #
    387596
    Location
    Michigan

    Question 4.2L cylinders 5, 6, 7, and 8 misfiring help please

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    So I have a 2007 Audi Q7 with the 4.2L V8 that is not idling smoothly and has the following codes.

    Random/Multiple Cylinder Misfire Detected P0300 Upper Limit Reached - Intermittent.

    Cylinder 8: Misfire Detected P0308 Upper Limit Reached - Intermittent.

    Cylinder 6: Misfire Detected P0306 Upper Limit Reached - Intermittent.

    Cylinder 5: Misfire Detected P0305 Upper Limit Reached - Intermittent.

    Cylinder 7: Misfire Detected P0307 Not A Plausible Signal - Intermittent.

    I unplugged be Oxygen Sensors to see if it would smooth out but it did not. I changed the coils from 5, 6, 7, 8 to 1, 2, 3, 4 to see if the codes changed but they did not. I also replaced the plugs with new ones and that didn't help. Hoping someone here might be able to help.

  2. #2
    Established Member Two Rings Corners4kids's Avatar
    Join Date
    May 11 2016
    AZ Member #
    373128
    My Garage
    2014 A6 3.0T
    Location
    Littelton, CO

    4.2L cylinders 5, 6, 7, and 8 misfiring help please

    Possibly MAF sensor. I got some of those codes a few thousand miles after I changed plugs and coil packs on my S5 4.2. Cleaned the MAF sensor (CRC makes a great spray cleaner) and it solved it for me. Might need a new part, but the cleaner is a cheap thing to consider trying.

    Just a thought. Might not be it, but it's an inexpensive option to test.


    Sent from my iPhone using Audizine mobile app

  3. #3
    Established Member Two Rings sfouRS's Avatar
    Join Date
    Jan 27 2013
    AZ Member #
    108336
    My Garage
    Bikes!
    Location
    Lehigh Valley, PA

    Check plugs & coil packs for those cylinders.

    Had this with mine, new plugs and coil packs and runs super smooth now.

  4. #4
    Established Member Two Rings
    Join Date
    May 18 2016
    AZ Member #
    373523
    Location
    Orlando

    Carbon clean it. If it still persist then replace all injectors.

  5. #5
    Active Member One Ring
    Join Date
    Jun 19 2018
    AZ Member #
    420914
    Location
    Idaho

    What was out come?

  6. #6
    Active Member One Ring
    Join Date
    Jun 19 2018
    AZ Member #
    420914
    Location
    Idaho

    So what was out come, Iíve got a 2008 Q7 4.2 doing same thing

  7. #7
    Active Member One Ring
    Join Date
    May 10 2017
    AZ Member #
    399233
    Location
    DMV

    Same thing happening to my Q7. Any word ?

  8. #8
    Established Member Two Rings 3g_bishi's Avatar
    Join Date
    Mar 03 2016
    AZ Member #
    369705
    Location
    DFW

    Itís gonna be an upstream o2 sensor on that side, or a vacuum leak on that side.


    Sent from my iPhone using Audizine

  9. #9
    Active Member One Ring
    Join Date
    May 10 2017
    AZ Member #
    399233
    Location
    DMV

    What about the mass airflow sensor?

  10. #10
    Established Member Two Rings 3g_bishi's Avatar
    Join Date
    Mar 03 2016
    AZ Member #
    369705
    Location
    DFW

    Buy some mass air flow sensor cleaner and try it but if it was maf it would miss on both sides.


    Sent from my iPhone using Audizine

  11. #11
    Active Member Two Rings
    Join Date
    Feb 02 2018
    AZ Member #
    413409
    Location
    Placerville

    Possible bad bank 2 cam tensioner. Should also see a p0321 code I believe if itís that

  12. #12
    Senior Member Two Rings volvofan's Avatar
    Join Date
    Sep 10 2016
    AZ Member #
    380607
    My Garage
    1998 Volvo S90 w/ 6.8L LS3
    Location
    MA

    Quote Originally Posted by 3g_bishi View Post
    Itís gonna be an upstream o2 sensor on that side, or a vacuum leak on that side.


    Sent from my iPhone using Audizine
    Having same issue on my s5 but on bank 1. Anything you can check in VCDS to nail it down to the O2 sensor?

    https://www.audizine.com/forum/showt...on-Bank-1-only
    Last edited by volvofan; 10-07-2018 at 06:34 AM.
    2011 S5 Coupe APRIII 90k

    Still slower than an Apache... but not by much.



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