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S4 Lump idle

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by GeoffDunk, Apr 21, 2014.

  1. GeoffDunk
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    GeoffDunk Member

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    Has anyone suffered from lumpy idle on their S4?

    It seems lately that my idle is feeling a little uneven and lumpy, its due a service as is being done next week but wondered what would cause this so I can get it dealt with at the time of he service?

    Also, is it true that there are two sensor for the oil level on the V8, I still get my min oil level warning come on when oil level is good and I have already replaced the oil pressure switch.
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  2. BRILLO
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    BRILLO Member

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    There's another sensor in the sump so change that when you change the oil.
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  3. dualmono21
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    dualmono21 Well-Known Member

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    lumpy idle could be one of a few things
    i would advise you have the car scanned and see if anything is not running correctly
    the main other thing to check is vac lines around the top of the inlet manifold

    if your having car serviced then thats an ideal time to swap the sensor in the sump
    unfortunately to swap it you have to remove the sump

    when you have replaced the sensor DO NOT turn on the ignition until you have replaced the oil in the sump as it can burn out the new sensor
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  4. rjm180
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    rjm180 Member

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    +1 You need to have it scanned.
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  5. GeoffDunk
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    GeoffDunk Member

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    Thanks for the info.

    Car has been scanned with no faults so I'll have the vac hoses checked.

    I think the idle has always been a little lumpy but seems a little worse lately.

    With regards to the sump sensor, I had been told a while ago about it but wasn't sure the person telling me really knew what they were talking about so thanks for confirming that and also the ignition detail.

    service will now include:
    full service
    Replace all engine mounts including snub mount
    B5 perches
    sump oil sensor
    vac hose check/replacement
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  6. dualmono21
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    dualmono21 Well-Known Member

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    geoff this is where vcds would come in really handy

    the car is showing no faults but problem persists , with vcds it would allow you to go into things like the maf sensor and check that
    it is within specification
    there are literally 100,s of measurement blocks which vcds allows you to go into and it will tell you if they are within spec or out of it
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  7. GeoffDunk
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    GeoffDunk Member

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    As stated, it has been checked (with VCDS) and shows no faults or issues, that's why I posted the question.

    my guy wants to replace the MAF sensor as a way of eliminating the issue and fault finding.
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  8. dualmono21
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    dualmono21 Well-Known Member

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    if you have access to vcds
    go into the engine measuring blocks and access the one for the maf
    there will be a range usually something like 150 - 300 if its reading above or below the stated range then yes by all means swap the maf but i wouldn't swap it just on a whim

    scanning the car for faults is one thing ... diagnosing faults using vcds is another
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  9. Mike.M
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    Mike.M Well-Known Member

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    as above..........use VCDS and check all cylinders are firing evenly etc via the engine measuring blocks.

    Wifes Mk5 Golf was lumpy and down on power.......the above discovered random misfires on cylinder 3 but with no faults logged.
    #9

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