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Cold start - blue smoke

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by Macdoon, Jun 5, 2013.

  1. Macdoon
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    Macdoon Well-Known Member

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    Hi all

    After hours of thread reading, still confused

    On cold start and up to temp, car is a wee bit lumpy, but puts out blue smoke and smells slightly, this only happens until up to temp.

    No fault codes. Injectors changed (on recall) 20k ago. EGR valve cleaned <10k ago. Oil & filter <5k ago and again yesterday with balancer shaft/hex drive upgrade. Full service (incl fuel filter) & cambelt change <20k ago. New turbo at 45k ish.

    Any ideas

    Cheers gang

    Mac
    #1
  2. unitzero
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    unitzero Active Member

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    I have a very similar issue and have also read thread upon thread with no definitive answer. in for any info
    #2
  3. NickB
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    NickB New Member

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    Are you burning oil?
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  4. matthew999
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    matthew999 Member

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    Macdoon, i think someone here changed the actuator on the inlet manafold, i tihnk it adjusts some flaps inside and this solved their lumpy idol issues, it might be worth a pop as apart from getting your hands dirty it is a cheep part

    cheers

    matt
    #4
  5. Macdoon
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    Macdoon Well-Known Member

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    No more than the usual fella, why what you thinking Nick
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  6. Macdoon
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    Macdoon Well-Known Member

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    Cheers Matt, might as well start there lol
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  7. tr3m5
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    tr3m5 Audi Newbie

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    Blue smoke is burning oil, if it's only from cold then somehow while the engine sits cold some oil is getting into the combustion system, could be a number of things but if it was someting serious like head gasket or turbo oil seals you'd see other symptoms including high oil consumption.

    However if the valve guides and/or valve stem oil seals are are worn then when the engine is cold oil can seep down from the head and collect either in the chamber or back of the valve, when you crank you get a puff of blue smoke as the oil burns off.

    I'd get a compression test done anyway and check there is no emulsion in the oil to be sure if you're worried. General rule is on a high mileage car if you're not using too much oil then don't worry about it.

    Changing the actuator won't stop the blue smoke mind.
    #7
  8. NickB
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    NickB New Member

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    The same as tr3m5 or shagged piston rings
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  9. sidibear
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    sidibear Looking for Zombies !! Staff Member Moderator

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    Nick, shagged pistons rings generally shows up under engine load rather than a cold start. Valve guide oil seals are a favourite. Miller Oils do an oil treatment that can sometime help with leaky seals.
    #9
  10. Macdoon
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    Macdoon Well-Known Member

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    Had a quick chat with a mate, he thinks there is a possibility that maybe an injector seal may be the issue. Anyway asthe injectors had been changed under recall and a 2 year warranty I phoned Audi and it's booked in tomorrow morning to check the seals :ermm:
    #10
  11. Avnt
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    Avnt Active Member

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    What was the outcome of the blue smoke& rough idle? Mine does it as well and it had injectors done last september
    #11
  12. ajax1976
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    ajax1976 Active Member

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    Sure it's blue smoke?

    Possibly coolant temp sensor giving false readings and over fueling the car on start up causing the smoke and lumpy running?

    Cheap and easy one to try first, unplug wiring from it night before then try starting next day from cold just to prove it first before replacing. Car will just revert back to generic values and should run fine with it unplugged.

    Alan
    #12
  13. Steve220
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    Steve220 Member

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    Overfuelling is black smoke. I'd go for your inlets are gunked up or valve stem seals.
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  14. ajax1976
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    ajax1976 Active Member

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    On start up engine is obviously cold so if its overfueling the engine will struggle to burn the excess fuel, white smoke is vaporised(unburnt) diesel, hence the smell.
    Only a suggestion as I had exact same issue myself, only when starting from cold and lumpy, goes away once warm.
    #14

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