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A4 B5 AFN Boost problems

Discussion in 'Diesel forum' started by BILKO1, May 4, 2009.

  1. BILKO1
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    BILKO1 Member

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    [May 4, 2009]
    Hi been reading these forums for hours trying to find a cure for a lack of power in my A4. The symptoms point to a vane problem in the turbo but these are moving freely along with the actuator. Over the last year i have had a new N75 valve and new MAF sensor both genuine Audi parts. All the vacuum pipes have been replaced including the one in the ecu. I have borrowed a snap on scanner and got the following codes
    00519 MAP Sensor - Out of Range -G71
    00553 Mass Air Flow Sensor -G70
    00575 Manifold Absolute Pressure Sensor

    I'm i right in thinking the MAP sensor in the ecu is faulty or could another componant cause these codes?

    What happens is if i floor the throttle in 1st and 2nd on so on the engine pulls/boosts fine but if i try to accelerate from say 2000rpm in 3rd the engine get to 3200 rpm hesitates slightly then goes limp home, if i flick the ignition on/off quickly the power comes back until i labour the engine again. HELP PLEASE i'm pulling my hair out (whats left)
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  3. evomaster3000
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    evomaster3000 Member

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    [May 4, 2009]
    Definatly an overboost issue, i have same issue at the moment, tho i'm pretty sure mine is the N75, i have a boost guage tho so i know whats going on.

    Ur MAP sensor may be faulty, as u've changed everything else and i've heard they can go, a boost guage would help verify this.
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  4. BILKO1
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    BILKO1 Member

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    [May 4, 2009]
    Thanks for the reply:) i can use the scanner in live reading mode to read the boost pressure, what am i looking for in psi?
    #3
  5. evomaster3000
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    evomaster3000 Member

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    [May 5, 2009]
    around 18psi maximum. usually 12-15 i'd say, been a while since mine was boosting normally, but 20+psi is too much for stock turbo and MAP

    Tho if ur MAP sensor is out it will send a higher reading than actual, which will give a false reading.
    #4
  6. BILKO1
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    BILKO1 Member

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    [May 5, 2009]
    I'm getting 24psi under load in 3rd gear up a hill:( need to get a standalone boost gauge now to see if the map sensor is telling the truth.
    #5

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