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no boost no fault codes???

Discussion in 'A4/S4 forum(B5 Chassis)' started by jbh, Jan 4, 2014.

  1. jbh
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    jbh TDi lover

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    [Jan 4, 2014]
    right ive not really been driving the car the wife has been running it. so today I nipped up the road with it and it was flat.. its not boosting and theres no fault codes..
    ive checked the turbo boost pipes theres no splits and everything looks fine.
    the turbo actuator appears to be stuck solid.. so is this a case of stuck vanes?
    so im going to strip the turbo off tomorrow whats my best way of checking it
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  3. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    [Jan 4, 2014]
    Your best and only friend now would be mr muscle oven cleaner :) !!

    Take the egr pipe off and spray down some vac hose into the turbine housing leave it half hour the start it up get it up to temp then give it a good thrashing !!!
    #2
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  4. TeKnodriver
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    TeKnodriver Biodiesel Purrrr

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    [Jan 5, 2014]
    if you have the original 'braided fabric over rubber' vac lines to/from N75 they can be split or porous under the fabric.
    I had 1 split and 1 about to split - causing reduced vacuum at N75...

    just replaced them with 4mmID silicone tubing - £2 or so per meter and one less thing that could be wrong
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  5. adamss24
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    adamss24 Well-Known Member

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    [Jan 5, 2014]
    If you have vag com/VCDS then you can cycle the N75 on and off in basic settings in engine, then you could see if the actuator is moving the arm. I had all sorts of faults before, broken vacuum actuators, stuck VNT, dead N75 and they not throwing codes all the time !
    #4
  6. jbh
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    jbh TDi lover

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    [Jan 5, 2014]
    Hi Chris ive tried a known good vacuum actuator on the turbo and its still not moving the rod. ive also used a hand vacuum pump on to the actuator and it wouldn't move the vnt lever so pretty sure its stuck.
    Im waiting to hear back about another car so I might end up breaking the N reg and making one good car out of 2 will update on this as soon as I know its going ahead. tomorrows job is to strip the turbo off and take it over to my mates work and get it stripped, cleaned and checked.
    #5
  7. PAULF
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    PAULF Active Member

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    [Jan 5, 2014]
    It sounds as if your vanes are carbonised.

    As Bradderz said, Mr Muscle it
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  8. mojocvh
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    mojocvh Member

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    [Jan 5, 2014]
    Is there a slightly more detailed DIY for this available, please.

    :sm4:
    #7
  9. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    [Jan 5, 2014]
    #8
  10. desertstorm
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    desertstorm Well-Known Member

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    [Jan 5, 2014]
    Why did you let the wife drive it ??. The turbo needs some heat to keep the carbon at bay. It doesn't do them any good babying them around.

    Karl.
    #9

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