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  1. #1
    Active Member One Ring
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    Feb 28 2017
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    394379
    Location
    Edmonton

    B7 S4 Misfiring Please Help!

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    Hello all,

    Thank you in advance for the help and advice.

    I have a B7 S4 and when I was driving down the highway my CEL came one. Pulled over to see if there was anything visibly wrong under the hood, and to my inexperienced eye, I didn't notice anything or any noise that seemed odd. Topped it up with some oil just to be sure it wasn't low. Once I got back into the city, I briefly smelt the rotten eggs smell (I have heard this can result from a bad/clogged cat). I also had a massive loss in power above around 3,800rpm. Exhaust node seems to be inconsistent(muffled) out of the left muffler and seems to have less fumes being emitted and the right side seems normal and consistent (symptoms of bad cat once again?)

    Car isn't making any strange noices and seems completely normal at idle with no shaking or rattling but as previously stated a huge loss in power.

    Took it into my local and trusted Audi/VW shop and they did 2 hours of diagnosing with no answer. Said they swapped around the plugs and coils and although the plugs looked like garbage (and recommeded replacing) said both of those weren't the issue.

    Hooked the car up and showed the following codes:

    Warm Up Catalyst; Bank 1
    P0421 - Efficiency Below Threshold - Intermittent

    Fuel Trim; Bank 2 (Multi)
    P1130 - System too Lean- Intermittent

    Cylinder 1
    Random/Multiple Cylinder Misfire Detected
    P0300 - Mil On

    P0301 - Misfire Detected - Intermittent

    Cylinder 2
    P0302 - Misfire Detected - Mil On

    As step 1, I am replacing the spark plugs tonight. Will do the coils if no change.

    If you have any suggestions, I appreciate any help I can get. Thank you!!
    Last edited by B7_S4; 02-28-2017 at 05:38 PM.

  2. #2
    Active Member One Ring
    Join Date
    Feb 15 2017
    AZ Member #
    393354
    Location
    Layton Utah

    Check injectors too. That's what my problem ended up being when something similar to this happened to me.


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  3. #3
    Active Member One Ring
    Join Date
    Feb 28 2017
    AZ Member #
    394379
    Location
    Edmonton

    I changed the plugs and coils and there is no change.

    When I step on it, it seems as though the car has a muffled/fluttered sound and power is being held back or restricted.

  4. #4
    Active Member One Ring
    Join Date
    Feb 15 2017
    AZ Member #
    393354
    Location
    Layton Utah

    Did you check your fuel injectors? When those clog it causes the motor to have a clunky, slow, restricted feeling. Just pull them out and check them and also check the o-ring seals for the injectors.


    Sent from my iPhone using Tapatalk

  5. #5
    Active Member One Ring
    Join Date
    Feb 15 2017
    AZ Member #
    393354
    Location
    Layton Utah

    And "bank 2 system to lean" code could possibly be a cam adjuster


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  6. #6
    Active Member One Ring
    Join Date
    Feb 28 2017
    AZ Member #
    394379
    Location
    Edmonton

    Had some time to look at the car again today and it seems to be making a fluttering type noise while revving the motor in neutral. Not sure if it's a timing chain related issue (tensioner/adjuster) noise or something else but sounds the same way the car acts when hitting 3,800 rpm.

    Here is a video revving the motor while parked.
    https://www.youtube.com/watch?v=61v4QnNCXk4
    Last edited by B7_S4; 03-04-2017 at 04:15 PM.

  7. #7
    Active Member One Ring
    Join Date
    Feb 28 2017
    AZ Member #
    394379
    Location
    Edmonton

    Any ideas on what that spuddering sound could be?

  8. #8
    Active Member One Ring
    Join Date
    Feb 28 2017
    AZ Member #
    394379
    Location
    Edmonton

    Update*

    After replacing the spark plugs and coils, there was no change in symptoms. I brought it to a nearby shop and they recommended changing the Crankcase Ventilation Valve. I replaced the valve myself and there seemed to be improvement as the car doesn't seem to shutter but there is still a huge lack of power.

    I also unplugged the MAF to see if that was a possible issue. The car idled the same but had no power when driving unplugged. That means the MAF is still good right?

    Does anyone have any other suggestions on why this could be? I am tired of taking taking it to the shop and spending money with no results...

  9. #9
    Established Member Two Rings icanfly's Avatar
    Join Date
    Jan 12 2012
    AZ Member #
    86544
    My Garage
    06 B7 S4 | STI Powered HandBuilt TarmacRallyCar | Skydiving Rig
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    Looking for a canyon to carve.

    If you've done plugs and coils and still have the issue, it's possible that it's a timing / chains issue. The sound is interesting, it sounds mechanical in nature. Can you get a little more footage, perhaps under power - driving?
    slow is fast...

  10. #10
    Active Member One Ring
    Join Date
    Mar 07 2016
    AZ Member #
    369887
    Location
    Portsmouth, NH

    Did you ever figure out what the issue was? I recently has a coil pack fail, I replaced the one pack and all 8 spark plugs. The CEL went away and the car accelerates, but it feels bogged down and doesn't have the power it normally does. Every now and then it will feel back to normal. Is it possible that the other 7 packs are just weak or would it misfire?

  11. #11
    Active Member One Ring Jesse Sheridan's Avatar
    Join Date
    Oct 17 2016
    AZ Member #
    383333
    Location
    70454

    Did you ever find out what was going on? I'm having the same problem..

    Sent from my Alcatel_5056O using Audizine mobile app

  12. #12
    Registered Member One Ring
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    Jul 29 2017
    AZ Member #
    403865
    Location
    East Bay/California

    Possibly a clogged precat

  13. #13
    Senior Member Three Rings badger.'s Avatar
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    Mar 31 2014
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    168335
    My Garage
    '05 S4 Sedan | '05 S4 Avant | '01 Lexus IS300
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    KY
    Items for Sale

    is your intake flapper still functioning correctly?
    '05 S4 Sedan Arctic White: JHM Intake Spacers | JHM ATF Cooler | JHM Auto-tensioner | 034 Motor Mounts | Apikol Snub | Slotted & Dimpled Rotors | AQ1200D w/Dual 10" CVRs | 35% Tint | Piggies | Fast Intentions Catback
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