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Thread: Fuel pressure reading dropping out

  1. #1
    Tuner in Training
    Join Date
    Mar 2015
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    15

    Fuel pressure reading dropping out

    I keep seeing an odd issue in VCM scanner with reading the low pressure fuel sensor (SAE) on C7 corvette. This has occurred in the last couple versions of the scanner, including 4.4.4 and the current beta. MPVI2 using USB cable.

    When reading the sensor, sometimes I will get a flatline response at 57.9psi with zero variations in pressure. If i disconnect and reconnect several times, then suddenly I will get a valid reading again and it will fluctuate as expected. Also, if I do a longer data record, you can actually watch the sensor readings work, then flatline for a bit, then work again.

    Ive delete a bunch of channels thinking there was congestion on the lines and changed polling rate, both without resolve. Deleted the PID and re added. Didnt help either. Graph attached. Ideas? Thank you!

    Capture.JPG
    Last edited by atljar; 07-28-2019 at 11:09 AM.

  2. #2
    Tuner in Training
    Join Date
    Mar 2015
    Posts
    15
    Update: Same issue with gds2 so it's not a scanner issue


    Unplugged the fuel pressure sensor, reading stays the same. Jumper the 5v reference at the sensor to the signal wire, reading stays the same.

    Planning on getting to the ecu tomorrow and unplugging the signal wire and seeing what it shows. If it stays at 57.9, that will eliminate a wiring issue as I've already eliminated the sensor as an issue. Then it Looks Like the ECU is garbage.

    Any idea if GM power train checks PCM checksums before authorizing warranty replacement? This would be an obvious hardware failure, not software.