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Thread: AC Pressure KPA to Voltage Range

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  1. #1
    Lifetime Member Tre-Cool's Avatar
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    Default AC Pressure KPA to Voltage Range

    Would I be correct to assume that the AC Pressure voltage sent to the ecu is 0v = 0kpa to 5v = 3447kpa?

    I'm re-using the ac pressure input for my ethanol sensor and just wondering if this could be the cause of my fans always running when the car is running.

    Cheers

  2. #2
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    Does your ethanol sensor output a voltage or a frequency/pulsewidth?

    Most of the ethanol sensors out there output a variable frequency from 50-150hz for content percentage, and a variable pulsewidth for fuel temperature.

  3. #3
    Lifetime Member Tre-Cool's Avatar
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    it's a factory sensor connected to a Zeitronix ECA, so i get 2 x 0-5v wires.

    I've wired them up to my EGR & AC sensor pins and using a calculated pid works well, but as the ls1 ecu can turn on/off fan's based on AC pressure I want to prevent anything from messing with my fan control.

    I've already done a drag season with it wired up, but i only realized on the weekend after looking at the tune again that perhaps this is why i was always running very cold ect.

    I will be playing around with the settings in the tune, but figured the efilive guys could give me a straight answer as to what the factory is expecting. Otherwise I'll just start logging the 0-5v signal and play around.

  4. #4
    Lifetime Member Tre-Cool's Avatar
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    looks like i was on the right track by maxing out the values for pressure enable and setting 1 for disable i now have proper control over the fans.

  5. #5
    Joe (Moderator) joecar's Avatar
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    Thanks for posting your results.

    Which table id...?

  6. #6
    Lifetime Member Tre-Cool's Avatar
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    G0911-G0912 for fan 1. In commodore this isnt used as fan1 is normally controlled by bcm

    G0918-G0919 for Fan 2.

    I still setup fan1 & fan2 turn on/off temps to the same though.

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