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  1. #1
    Active Member One Ring
    Join Date
    Dec 27 2024
    AZ Member #
    999466
    Location
    Bostoin, MA, USA

    Question Misfire with no codes?

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    Hi all. I have a 14 SQ5 that I am having some trouble with

    I posted the following in another forum

    "The what,
    I recently(today) did a spark plug , oil filter, and supercharger oil service on my 14 SQ5 and now my car struggles on idle. It feels like its missing, there is a rough idle, shuddering, and i hear popping coming out of the exhaust. Measuring the misfire since start on VCDS gave me multiple misfires on cyl 3-6, with 1 and 2 being fine and 3 being the worst. I checked gap at .7mm(.28") and also torqued down to 25ft lb(33nm). Coils are seated properly. Plugs are NGK Rs that i got off of FCP. The car did not have any of these issues before I did this stuff. From reading some of the forums, the intake manifold runner valves could be in the wrong position? Could this be the case for me? I just took the supercharger off to change its oil(it was completely dry), would just the removal of the supercharger alone affect the valve location? Is there a way to test the valve? I am also certain that when I reinstalled the supercharger I installec all the vac tubes correctly and that i did not kink any of them.

    The wierd,
    Despite these issues, The car does not throw a single code. It baffles me how bad this car is running and its not throwing a single code.

    The stupid.
    When I was redoing the plugs and supercharger. I put some litthium grease on the boots in place of dielectric grease. Could this be the cause of my misfire?. I also added some on the o-rings for the supercharger and the PCV o-ring as I was taught at work to use lithium grease on o-rings to prevent them from binding as things are installed. Was this the correct move?

    Any help or feedback is appreciated

    Thank you, MP

    Update

    I started my car up with VCDS connected. My short term fuel trim when the car entered close loop was in the -10 to -7 range indicating it was running rich. Before the closed loop it would run very rough, but close loop it pretty much stabilised. What could be the cause of this?

    I also took the supercharger off and found that the breather pipe was in the front of the engine valley. I dont know if it fell of when i installed the supercharger or if it fell off when i removed the supercharger this time. I will reinstall and find out.

    What do you guys think is going on?"

    What do you guys in AZ think is going on with my car?

    Currently my supercharger is off right now. I suspect my misfire is causing the rich running, but i cannot for the life of me figure out why it is missing. I have cleaned out the grease coils and the plugs. I can try cleaning the plug wells too if that might do something. Cyl 1 and 6 are misfiring, less than yesterdays 3-6. I figure a simple removal of the supercharger and reinstall might fix some issues. Is there anything specific I should make note of when reinstalling the supercharger?

  2. #2
    Veteran Member Four Rings TexasDfwS4's Avatar
    Join Date
    Sep 10 2012
    AZ Member #
    100226
    Location
    DFW

    If you accidentally hit the tip of the plug on the grease that would do it.
    2018 S6 Glaser white Black/Optics, Sport, ACC, HUD, CF, etc. NO bang/O
    2017 Q5 3.0 Ibis W/ BO with S-line
    Gone 2018 SQ5
    Gone 2013 B8.5 S4
    Gone 2012 S4
    Gone 2012 Q5
    Gone 2009 Q5

  3. #3
    Active Member One Ring
    Join Date
    Dec 27 2024
    AZ Member #
    999466
    Location
    Bostoin, MA, USA

    I cleaned all the seals, relubed them and put the supercharger back on. It seems to be holding. Perfect startup. No more misfires. Thanks guys

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