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Thread: MAP Sensor.. Is this normal?

  1. #1

    MAP Sensor.. Is this normal?

    Car is 2005 C6 with a built 402 and a Twin Turbo. I got the 12615136 2 bar map and I set the MAP Sensor Linear to 200 kpa, Offset to 8.33 and the Linear B to 66.67.

    When I log with the car Key on and car off, the MAP reads 101 kpa.

    Is that normal? I thought that it should go to 200 kpa or a little bit more than that.

  2. #2
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    Quote Originally Posted by fe9_fe9 View Post
    Car is 2005 C6 with a built 402 and a Twin Turbo. I got the 12615136 2 bar map and I set the MAP Sensor Linear to 200 kpa, Offset to 8.33 and the Linear B to 66.67.

    When I log with the car Key on and car off, the MAP reads 101 kpa.

    Is that normal? I thought that it should go to 200 kpa or a little bit more than that.
    101 kpa is exactly atmosphere pressure, so it is ok.

    http://en.wikipedia.org/wiki/Atmosphere

  3. #3
    Thanks for your reply !

    It should read more than atmosphere because it's a two bar map.

  4. #4
    with key on and car off it can't read more then atmosphere pressure

  5. #5
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    Quote Originally Posted by fe9_fe9 View Post
    It should read more than atmosphere because it's a two bar map.
    Atmosphere is atmosphere with the key on engine off regardless of what bar sensor you are using. The 2 bar allows you to sense MAP above 1 bar, boosted.

  6. #6
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    Quote Originally Posted by fe9_fe9 View Post
    Thanks for your reply !

    It should read more than atmosphere because it's a two bar map.
    It's working fine, as long as you're at sea level. With KOEO, the sensor is reading the pressure in the manifold, which is atmospheric.

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    Quote Originally Posted by fe9_fe9 View Post
    Thanks for your reply !

    It should read more than atmosphere because it's a two bar map.
    Yep, but only when in boost.

    0...100 kPa is vacuum area. This is where the "first" bar comes from.

    Exactly 100 kPa is atmosperic pressure.

    100...200 kPa is a boost area. This is where the "second" bar comes from.

    So 2 bar sensor sees vacuum (from zero to 100 kPa) as well as boost (from 100 kPa up to 200 kPa).

    Similarly, 3 bar sensor sees max one bar vacuum and up to 2 bar boost.

    Boost is typically referred in addition to atmoshperic pressure. So 1 bar boost = 14.7 psi = (100 kPa athmosperic pressure + 100 kPa boost =) 200 kPA from PCM perspective.

    Huh, difficult to say in words; single diagram would show everything much more easily..

  8. #8
    I was confused by thinking that if KOEO, then the MAP will read its max value.

    Thanks a lot for the info