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Thread: Flex Fuel Sensor Issue

  1. 02-07-2020 #1
    Skooba
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    Flex Fuel Sensor Issue

    I have a 2015 Camaro SS that has a flex fuel sensor installed. While doing my most recent data log I noticed I was suddenly pulling a lot of fuel on my STFT and LTFT. I log my alcohol % all the time and I noticed when I started the log I had 9.4% alcohol at one point I had 100% alcohol and my alcohol % reading anywhere in between. I?ve only had pump 93 in the tank for the last several fill ups and haven?t gotten gas from anywhere I haven?t gotten gas from before. I stopped and turned the sensor off in HPT. After that it read 0% as expected and the fuel trims returned to normal range vs pulling almost 40% between STFT and LTFT. Could my sensor be failing or is there something I?m missing that could cause my flex fuel sensor to go ape shit all of a sudden?
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  2. 02-07-2020 #2
    ABADZL1
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    I have seen failed sensors behave exactly how you describe. I have also seen aftermarket coils cause this issue for the sensors that are powered by a coil pack.

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  3. 02-07-2020 #3
    Skooba
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    Quote Originally Posted by ABADZL1 View Post
    I have seen failed sensors behave exactly how you describe. I have also seen aftermarket coils cause this issue for the sensors that are powered by a coil pack.
    Alright. I don’t have aftermarket coils so I’m going to guess the sensor has failed.

    Does anyone know if I can shoot the sensor with a multimeter and see if it’s bad that way or should I just look at replacing it?
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  4. 02-07-2020 #4
    ABADZL1
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    You would need a multimeter that can measure the Hz signal. Not the voltage. 50hz = 0% Alc. 150hz = 100%
    Last edited by ABADZL1; 02-07-2020 at 11:48 AM.

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  5. 02-07-2020 #5
    Skooba
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    Quote Originally Posted by ABADZL1 View Post
    You would need a multimeter that can measure the Hz signal. Not the voltage. 50hz = 0% Alc. 150hz = 100%
    I’m an aircraft mechanic by trade so there is no issue there. Do I check the Hz at the wire going to the ECM or do I check a different wire?
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  6. 02-07-2020 #6
    ABADZL1
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    I'm an Aircraft mechanic also. Lol The wire going to the ecm would be correct

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  7. 02-07-2020 #7
    07GTS
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    check what the default percentage is as thats where it goes when sensor fails, personally i have that at a safe richer side like 80% so even if im on petrol and it fails is fails rich if im on ethanol is is still safe as stock can fail to a lower percentage which if ur on e85 and fail to e10 u will lean out
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