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Cold weather initial lumpiness!!!

Discussion in 'A4/S4 forum(B5 Chassis)' started by phoenixv6quattro, Nov 25, 2010.

  1. phoenixv6quattro
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    phoenixv6quattro staylowmovefast

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    Hello Gents....

    When the car is started from cold and ONLY on zero or sub-zero mornings the tickover is initially very rough and will stall when revved for the first couple of mins only. When she settles down (typically 2-3 mins) she is right as rain. I have changed the throttle body (new) along with just about every other part that isn't inside the engine over the past year or so. Any ideas gents? Rather annoying especially when in a rush to get to work (when I'm home!-lol!). This prob has been reported to me by my nephew thats borrowing it untill I return to sunny britain! Though I must say I'm looking forward to the cold weather as its redders here in Africa!...No its not a bloody holiday wish it was! Though I wouldnt come here as Africa is generally a frightfully experience (unless your the bush tucker man or that weirdo Bear G).

    Ollie

    :sos:
    Last edited: Nov 26, 2010
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  2. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Vagcom scan would be in order to see if anything pops up.

    Perhaps a faulty coolant sensor meaning the cold start enrichment is incorrect?
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  3. phoenixv6quattro
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    phoenixv6quattro staylowmovefast

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    Hello Aragorn. Yes possibly. However I installed a brand new one 6 months ago! Got me thinking now if the silly little bastard at the Audi dealership sold me the wrong one? Though the car runs like a dream after the initial 2 mins when the weathers freezing or starts like normal when its not cold. Got me scratching my head this one! I havnt got vagcom/vcds. I was going to invest in one last year but didnt get round to it!
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Theres only one that would fit anyway, so i cant see him having messed it up.

    First stage is checking if the ECU has any electronic faults, if its all clean, then i'd be looking at mechanical things.

    Ignition is much more difficult when the engine is stone cold, so for instance marginal spark plugs or slightly dodgy leads might manifest as a lumpy missfire when cold then clear once the engines got a bit of heat into it.
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  5. phoenixv6quattro
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    phoenixv6quattro staylowmovefast

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    Good points! Cheers mate!
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  6. sdk778
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    sdk778 Member

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    Initial lumpyness is usually derived from a borked G62 sensor.

    Common on the 4 cylinder cars.
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  7. phoenixv6quattro
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    phoenixv6quattro staylowmovefast

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    Hello mate. Mines a V6 not a 4 pot. The coolant sensor was changed with a new one bout 6 months back. The problem was located and it was incorrectly gapped spark plug on cylinders 2 and 6. The rough idle for the first few mins on baltic mornings has now gone (as I'm told by my nephew-the little bastard thought he had buggered my car up!-lolololol!). With a bit of luck she will not throw up anymore probs untill I get the PES kit on there when I finally get back to snowy blighty.
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  8. sdk778
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    sdk778 Member

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    I realised yours was a V6. just stating that the G62 is a retard when it comes to coolant sensors, fails with no warning. The other coolant sensor, the MFTS is also related to cold start issues. Still, a badly gapped plug is a hell of a lot cheaper than a sensor!!! Glad all is well pal.
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