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Anyone good with logs?

Discussion in 'A3/S3 Forum (8L Chassis)' started by vroomtshh, Oct 12, 2012.

  1. vroomtshh
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    vroomtshh Active Member VCDS Map User

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    [Oct 12, 2012]
    I'm having some problems with the car at high revs - 4500 and above.

    I did a few logs and have screenshots below.
    I never lifted my foot during the logs, yet it seems the throttle angle changes.
    It sounds and feels very much like a misfire, but I have new coilpacks, and plugs, so not sure what else could cause a misfire.
    No fault codes
    [​IMG]
    [​IMG]

    Further to this, I've had a mapper look at it, and he thinks the problem is with requested lambda vs actual lambda. He suggested my fuel pump or injectors might not be up to the task. Does that sound right?
    #1
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  3. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Oct 12, 2012]
    The AFR looks to be a symptom rather than the cause... looking at block 002 you can see that the injectors are maxed out... this is most likely a symptom of a tired fuel pump... fuel pressure test would confirm this..

    Knowing what model/year and the spec of the car would help...

    You don't control the throttle angle the ECU does... the position of the throttle pedal is unrelated to throttle plate angle, its all to do with load and torque request... if the ECU decides you are meeting the requested torque (even with a planted pedal) then it will close the plate accordingly to maintain it...

    There is quite a drop off on load but again that could be symptomatic of another problem...

    Get the fuel pressure checked to confirm the pump is tired first..

    <tuffty/>
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  4. vroomtshh
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    vroomtshh Active Member VCDS Map User

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    [Oct 12, 2012]
    Its a 2003 A4 quattro sport with K03s, decat and exhaust and a custom map.

    How can you tell the injectors are maxed out? Logging etc is pretty alien to me.

    Any ideas how I can do a pressure test on that car?
    #3
  5. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Oct 12, 2012]
    block 002 has the injector ms.....
    dial in the rpm and injector ms into this sheet> Stealth 316 - Injector Duty Cycle Calculation

    and duty cycle is calculated
    100% is max.. and you dont want to be at 100%

    A4 might be returnless fuel system... if you have a pressure take off measure it under boost and it should be its FPR rated pressure + boost if its healthy
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  6. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Oct 12, 2012]
    Injector duty cycle... an on time of much over 20ms is essentially flat out/open all the time...

    You use a fuel pressure tester :)
    [​IMG]

    Ideally needs to be done on a dyno so you can see the fuel pressure as boost comes in... the fuel pressure regulators (FPR) on 1.8t's are rising rate and are rated pressure of FPR plus boost... on A3/S3 8L's (this section) FPR's are 3bar but I think yours will be a 4bar FPR so on idle fuel pressure should be just under 4bar rising to just over 5bar based on your logs... 4bar FPR's are quite hard on fuel pumps...

    <tuffty/>
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  7. vroomtshh
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    vroomtshh Active Member VCDS Map User

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    [Oct 12, 2012]
    Mine is definitely a 4bar FPR and a returnless system.

    Will get checking it at the weekend.
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  8. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Oct 12, 2012]
    The injectors may be maxed out, but the fuelling is more or less following the requested? Its not perfect, but its not miles out either.

    Its dropping into limp/throttle cut though, you can see it drops back to actuator pressure and cuts throttle around 5700rpm.

    It tries to recover at the next block, then gives up again.


    When has this started?
    #7
  9. vroomtshh
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    vroomtshh Active Member VCDS Map User

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    [Oct 12, 2012]
    I think it started after it was mapped. But I'm not 100% sure, as I don;t think I ever really revved it that high before it was mapped. Probably the odd time, but not regularly.

    I've been trying to sort out a few issues and fault codes over the last month or so, and now everything else is sorted, I'm still having this problem. I didn;t want to instantly blame the map when I had a couple of fault codes.
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  10. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Oct 12, 2012]
    Who mapped it?
    #9
  11. vroomtshh
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    vroomtshh Active Member VCDS Map User

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    [Oct 12, 2012]
    Does it matter? I don;t really want to give someone a bad name on the net when I'm not sure thats the problem, and hes been as helpful as can be
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  12. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Oct 12, 2012]
    From a mapping perspective its looks ok... the data in the logs suggest hardware issues...

    <tuffty/>
    #11
  13. vroomtshh
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    vroomtshh Active Member VCDS Map User

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    [Oct 12, 2012]
    Thanks. Thats really what I needed to know. Mapping problems are easier/cheaper to sort though :lmfao:
    #12

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