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Thread: MAP Voltages

  1. #1
    Hybrid booster
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    MAP Voltages

    Having issues finding a suitable replacement MAP sensor. Since I have the GM style connector for my 3 bar, I figured I'd look into a GM 2 bar instead. Below is the pressure to voltage conversion for the GM sensor, I'd assume it's the same with our cars, but figured I'd post it here for anyone to tell me it's wrong.

    Manifold Pressure
    (relative sea level / absolute)
    2 Bar
    MAP Output
    14.31psi / 29.01psi
    4.90V
    14.00psi / 28.70psi
    4.84V
    13.00psi / 27.70psi
    4.67V
    12.00psi / 26.70psi
    4.50V
    11.00psi / 25.70psi
    4.33V
    10.00psi / 24.70psi
    4.16V
    9.00psi / 23.70psi
    3.99V
    8.00psi / 22.70psi
    3.82V
    6.00psi / 20.70psi
    3.47V
    4.00psi / 18.70psi
    3.13V
    2.00psi / 16.70psi
    2.79V
    0.00psi / 14.70psi
    2.45V
    5.00inHg / 12.24psi
    2.03V
    10.00inHg / 9.78psi
    1.61V
    15.00inHg / 7.33psi
    1.19V
    20.00inHg / 4.87psi
    0.77V
    25.00inHg / 2.41psi
    0.35V
    29.10inHg / 0.40psi
    0.02V

  2. #2
    Slugmobile & MeanMini Caretaker Turbo Mopar Contributor wheming's Avatar
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    Re: MAP Voltages

    If you need a new MAP sensor, the 3 & 4 bar Omnipower products came recommended by others.
    I think i had purchased my 4 bar from Amazon.
    Wayne H.

    '91 Dodge Spirit ES 2.5L turbo 5spd
    '05 PT GT 2.4T HO autostick (RIP)
    '89 Plymouth Acclaim 2.5L turbo auto, "Slugmobile" yes, THE Slugmobile!
    '89 Dodge Caravan SE 2.5L turbo auto, "Mean Mini" yes, Gus' Mean Mini! (Current best 11.699 @ 114.43 mph! - Oct 15th, 2022 Cecil County Dragway, MD)
    MeanMini dragracing videos: https://www.youtube.com/playlist?lis...URZLB1RxGYF6vw
    and other cars, trucks and motorcycles
    https://www.youtube.com/user/SlugmobileMeanMini

  3. #3
    Hybrid booster
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    Re: MAP Voltages

    I have a good working 3 bar MAP, what I lack is a good working 3 bar calibration. Waiting for Rob to start selling flashable computers again. Looking for a 2 bar to hold me over.

  4. #4
    Slugmobile & MeanMini Caretaker Turbo Mopar Contributor wheming's Avatar
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    Re: MAP Voltages

    2bar map or 2bar cal? I may have a spare 2bar map sensor
    Wayne H.

    '91 Dodge Spirit ES 2.5L turbo 5spd
    '05 PT GT 2.4T HO autostick (RIP)
    '89 Plymouth Acclaim 2.5L turbo auto, "Slugmobile" yes, THE Slugmobile!
    '89 Dodge Caravan SE 2.5L turbo auto, "Mean Mini" yes, Gus' Mean Mini! (Current best 11.699 @ 114.43 mph! - Oct 15th, 2022 Cecil County Dragway, MD)
    MeanMini dragracing videos: https://www.youtube.com/playlist?lis...URZLB1RxGYF6vw
    and other cars, trucks and motorcycles
    https://www.youtube.com/user/SlugmobileMeanMini

  5. #5
    Hybrid booster
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    Re: MAP Voltages

    2 bar map sensor. TIII shows the same map as TI in the efisch, but none of the replacements I purchased worked.

  6. #6
    turbo addict
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    Re: MAP Voltages

    Quote Originally Posted by EaZyE426 View Post
    but none of the replacements I purchased worked.
    Maybe the issue isn't the MAP sensor?

  7. #7
    Hybrid booster
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    Re: MAP Voltages

    The 3 bar does not generate a code 14 like the others I've tried. I followed the diagnostic flowchart. If the map voltage is high, replace map sensor. If the map voltage is low, replace ECU. But since the 3 bar worka fine, I'm confident it's not a wiring or ECU issue.

    - - - Updated - - -

    I can't check the map voltage directly since when I put the volt meter on, the ECU immediately sees 5volts, thinks it at 15 psi, and stalls the car.

  8. #8
    Supporting Member Turbo Mopar Contributor
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    Re: MAP Voltages

    Quote Originally Posted by EaZyE426 View Post
    The 3 bar does not generate a code 14 like the others I've tried. I followed the diagnostic flowchart. If the map voltage is high, replace map sensor. If the map voltage is low, replace ECU. But since the 3 bar worka fine, I'm confident it's not a wiring or ECU issue.

    - - - Updated - - -

    I can't check the map voltage directly since when I put the volt meter on, the ECU immediately sees 5volts, thinks it at 15 psi, and stalls the car.
    I assume you are "backprobing" the connector while it is attached to the MAP sensor. If so, I suspect there is something wrong with your meter or it is an old analog type. Modern DVM(Digital Volt Meter) have input impedance of 10 M so it will not significantly "disturb" your voltage reading when attached.
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  9. #9
    Hybrid booster
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    Re: MAP Voltages

    I was backprobing, but I was using a modern DVOM. It's a few years old and has seen better days. It rattles of you shake it, maybe something broke loose? Lol

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