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  1. #1
    Established Member Two Rings
    Join Date
    Sep 21 2015
    AZ Member #
    357021
    Location
    Indiana

    B8.5 Misfire Issues

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    I'm having issues with my 2014 A4. I was due to change the PCV for some time due to O2 Sensor Codes (O2 Sensor Bank 1 Sensor 2 Delayed Response Lean to Rich, O2 Sensor Bank 1 Sensor 2 Delayed Response Rich to Lean, Catalyst System, Bank 1 Efficiency Below Threshold). The car seemed to run ok up until last Wednesday.

    The temperature outside warmed up (30 to 70 in 3 days) and when I got home on Wednesday, the car started misfiring at idle when I pulled into my driveway.

    I let the car sit for a few days thinking maybe it was just the PCV issue, and I really needed to get off my ass and change it. I replaced the PCV, and the car is definitely running better. I'm not getting anymore O2 Sensor Codes, but I still have a misfire on Cylinder 1 and a Random Misfire CEL.

    I replaced the spark plugs this morning and swapped the coil packs around.

    Now I'm getting an additional P125000 (Fuel Level too Low) code. I have a full tank of gas.

    I had a carbon cleaning about 10,000 miles ago along with new fuel injectors.

    I haven't run a compression test yet on cylinder 1, but I'm working on that.

    Any ideas?

  2. #2
    Active Member Two Rings
    Join Date
    Mar 25 2018
    AZ Member #
    416102
    Location
    Toronto

    Could be the high pressure fuel pump. How many miles on the car?

  3. #3
    Senior Member Three Rings audrobotic's Avatar
    Join Date
    Jun 30 2014
    AZ Member #
    260490
    Location
    SoCal

    I assume that after you swapped plugs and coils around you still got the same cylinder #1 misfire. (plus the new fuel level low code).

    The compression test is a good idea. Sounds like its a fuel delivery issue. But youll have to take a fine tooth comb to everything air to track down the culprit. Maybe one of new injectors is bad or clogged.
    Current: 2013 A4 | Past: 2010 A4

  4. #4
    Established Member Two Rings
    Join Date
    Sep 21 2015
    AZ Member #
    357021
    Location
    Indiana

    Quote Originally Posted by adamleaf8601 View Post
    Could be the high pressure fuel pump. How many miles on the car?
    70,000 miles.

  5. #5
    Established Member Two Rings
    Join Date
    Sep 21 2015
    AZ Member #
    357021
    Location
    Indiana

    Quote Originally Posted by audrobotic View Post
    I assume that after you swapped plugs and coils around you still got the same cylinder #1 misfire. (plus the new fuel level low code).

    The compression test is a good idea. Sounds like its a fuel delivery issue. But youll have to take a fine tooth comb to everything air to track down the culprit. Maybe one of new injectors is bad or clogged.
    Yes - it's still cylinder 1 after plugs / swapping coil packs.

  6. #6
    Established Member Two Rings
    Join Date
    Sep 21 2015
    AZ Member #
    357021
    Location
    Indiana

    Just tested the compression. Cylinder 1 is about 10% lower than the rest.

  7. #7
    Established Member Two Rings DannyFB8's Avatar
    Join Date
    Jan 23 2017
    AZ Member #
    391423
    Location
    Jersey city, NJ

    Sad to say, this sounds a little all to familiar. Your next test should be a leakdown test. Had similar symptoms on my b8.5 throwing excessive misfire codes even after changing, injectors, pvc, new plugs. Did the leakdown test and cyl 1 kept failing and came to find out I had a scorn cylinder 1.


    Sent from my iPhone using Audizine

  8. #8
    Established Member Two Rings
    Join Date
    Sep 21 2015
    AZ Member #
    357021
    Location
    Indiana

    Quote Originally Posted by DannyFB8 View Post
    Sad to say, this sounds a little all to familiar. Your next test should be a leakdown test. Had similar symptoms on my b8.5 throwing excessive misfire codes even after changing, injectors, pvc, new plugs. Did the leakdown test and cyl 1 kept failing and came to find out I had a scorn cylinder 1.


    Sent from my iPhone using Audizine
    I drove it today while watching the misfire counter. It only seems to do it at idle. It doesn't do it when I step on the gas. Did you have those symptoms?

  9. #9
    Established Member Two Rings DannyFB8's Avatar
    Join Date
    Jan 23 2017
    AZ Member #
    391423
    Location
    Jersey city, NJ

    I had misfires at both idle and while pressing on the gas. Car was reluctant to start but after a couple of crank it did but I had also multiples other symptoms that supported the scorn cylinder such as oil leakage between timing chain cover and head block, 0 compression from cyl 1, oil deposits. Are you getting any of those?


    Sent from my iPhone using Audizine

  10. #10
    Established Member Two Rings
    Join Date
    Sep 21 2015
    AZ Member #
    357021
    Location
    Indiana

    Quote Originally Posted by DannyFB8 View Post
    I had misfires at both idle and while pressing on the gas. Car was reluctant to start but after a couple of crank it did but I had also multiples other symptoms that supported the scorn cylinder such as oil leakage between timing chain cover and head block, 0 compression from cyl 1, oil deposits. Are you getting any of those?


    Sent from my iPhone using Audizine
    Not yet, thankfully. Compression seems ok on Cylinder 1 and no oil leaking or excess burning. Seems like it's either fuel related or a vacuum leak.

  11. #11
    Established Member Two Rings
    Join Date
    Sep 21 2015
    AZ Member #
    357021
    Location
    Indiana

    Update - Replaced the breather tube, removed the O2 spacers I was using before I was tuned, and tightened down the PCV a bit more.

    The seems to be idling normally now and the ticking sound is gone. Cylinder 1 seems to misfire still when I let off the gas. Might be another vacuum leak somewhere...



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