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Does the MAF control fuel trim for each bank?

Discussion in 'A3/S3 Forum (8L Chassis)' started by finesse, Mar 22, 2010.

  1. finesse
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    finesse Active Member

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    Vagcom says fuel trim at bank 1 is rich, would a MAF change sort this or is this a possible injector problem?

    2001 AMK

    P.S
    If the oxygen sensor was faulty, would it come up in a scan?
    Where the feck is the Fuel Pressure Regulator?

    :)


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  2. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Vacuum leak could be the cause of that... check Block 032 of the Engine group when the engine is warm and idling

    <tuffty/>
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  3. finesse
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    finesse Active Member

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    ok thanks will do, what range of figures would you expect?
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  4. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Should be as close to 0% (+/- 5%) as poss... first value is idle trim and is the one I think this relates too... if its adding fuel (positive number) I would suspect a substantial vacuum leak... probably a split pipe (or pipes normally) under the inlet manifold. Check any pipe from the inlet manifold following them back as far as they go for splits etc... they may not be obvious so make sure you look all around the pipes...

    FYI, the fuel pressure regulator is the round bit on the end of the fuel injector rail. This too has a vacuum pipe and is prone to splitting... this could be the cause of this issue by creating a vac leak as well has not being able to control fuel pressure due to the vac pipe controlling it having a vac leak...

    <tuffty/>
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  5. badger5
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    badger5 RIP S3dave Site Sponsor

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    also look at block 001 on idle and cruising throttle, full throttle etc..
    block 031 is lanbda spec and request, and you will see ecu's compensation to achivee this via block 001, so if leaks are present then you would expect to see 001 have largish numbers.
    also log maf output on 003 incase its shagged.. and under reading. (usually pops a lean code not rich tho)

    It could also of course be a mis-readin lambda

    log some stuff as suggested and report back
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  6. finesse
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    finesse Active Member

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    Excellent! Thank you, will report back.
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  7. basil brush
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    basil brush Member

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    sorry to resurect an old thread but thought it better than starting a new one ?
    did you sort this ?
    i only ask as i have a 1.8t flooding on cold start up and i have just found 2 massive splits in the breather system (under intake manifold) and wonder if this could be related ?
    also finesse are you a vcds owner in southminster ? if you are i would like to cross your palm with silver to use you and you vcds
    regards marc
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