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Air fuel ratio

Discussion in 'A3/S3 Forum (8L Chassis)' started by and32, Nov 19, 2009.

  1. and32
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    and32 Member

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    [Nov 19, 2009]
    Hello just a quick question does anyone know if you can use vagcom share version to check if my car is running lean. I ask because i had the car, a 1.8 t 1999 audi a3 remapped recently, its a k03s with all usual bits and a custom code phase 2. I have been having problems with low boost since its been done, i have now sorted the problem (split vac pipe) but it is hitting 20 psi on occasion and i dont want it running lean. My thoughts are that when it was mapped if the pipe was split and i have now put a new one on its getting more air. Jbs has told me not to wory and the ecu will compensate for the bit of extra air, what do u think.
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  3. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User

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    [Nov 19, 2009]
    To a point they are right. As you have the early type ECU you will probably only be able to chack the Lambda voltage to see if it's in spec at .8v iirc. The older ECUs don't have accessable info for fuel trims etc iirc
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  4. and32
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    and32 Member

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    [Nov 19, 2009]
    so do you think i should just believe them and it will be ok
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  5. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User

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    [Nov 19, 2009]
    Have you vagcom?

    Thats what you need to check it, then check lambda voltage as stated, that will tell you.

    Tho TBH you won't have been sucking that much air from a simple split Vac pipe, it will probably just have been altering the way the wastegate opened/closed, or the DV worked, depending which hose it was.

    I would however make sure the FPR vac pipe is in a good state of repair. That can have a drastic effect on fueling
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  6. m444ty p
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    m444ty p Member

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    [Nov 19, 2009]
    what is the FPR vac pipe ?
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  7. Mpathe
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    Mpathe 1st gear

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    [Nov 20, 2009]
    Fuel Pressure Regulator vac pipe connects to the fpr valve and when on boost, it lifts the fuel pressure and gives more fuel so you dont run lean
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