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3.0 tdi .... Goes flat in 5th gear only ......

Discussion in 'Diesel forum' started by NotNormal, Nov 24, 2013.

  1. NotNormal
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    NotNormal Member

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    The car :


    Audi A6 3.0 TDi Auto Quattro 2009 facelift
    CDYA engine code


    The problem :


    Hold a constant 2/3 's throttle - run through the gears without deviation - 1,2,3,4 all pull strong, smoothly drops into 5th and goes flat, still accelerates, then pulls strongly again in 6th


    The fuel econ is also poor, 25mpg to the tank (long range 80L tank) - mpg measure correctly from fill up to fill up.


    The parts it's had recently :


    Complete fuel system : hpfp, lpfp, regulator, injectors x6, rails x2, link pipes, vacuum pipes, filter, filter housing, relays, entire wiring and ECU check, tank swabbed out, front to rear fuel lines flushed out, software update, adaption values reset (fully adapted again now)


    Complete auto box rebuild - new oil, new transfer box oil, new rear diff oil


    Turbo inlet seal replaced


    Swirl flap updated and new rods fitted (both banks) (full adaption since this also)


    The car has no fault codes sorted, non pending




    All the work work has been carried out at main dealer Audi




    Anyone got any ideas ..... We are stumped .....
    #1
  2. Jamie-S
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    Jamie-S Member

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    Why has it needed all that work?
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  3. desertstorm
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    desertstorm Well-Known Member

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    How many miles has the car done ??. Seems strange that the car pulls fine in all gears except 5th yet they seemed to have decided that it may be a fuelling issue as they have replaced the entire fuel system by the looks of it.
    I would be doing some data logging on the road checking boost pressures, EGT temperatures, DPF differential pressures , Pump fuel pressures etc.
    Is it the gearbox that is limiting torque on the engine for some reason.

    Karl.

    Karl.
    #3
  4. NotNormal
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    NotNormal Member

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    fuel system was down to swarf in the system, a component breaking down - it was a recall for certain engine codes and sizes
    swirl flap rods - common issue
    inlet o ring - relatively common issue again, you'd see an oily buildup around the pipe at the turbo end on the compressor housing



    They didn't attribute the fuel problem to this - the fuel system was replaced due to a component breaking down causing swarf giving a code of low fuel pressure P0087 - any when this happens it went into limp mode

    I was just clarifying what's been done ti try and be comprehensive

    my cars covered 103,000 miles

    DPF has been checked - both computer and physically - all ok


    thanks for your input so far, food for thought .... Will investigate further ....
    #4

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