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Thread: 99 Trans am Fuel trim problem

  1. #1

    99 Trans am Fuel trim problem

    Im trying to tune my VE table but am unable to get any fuel trim data through the scanner. I realize it is not going into closed loop mode, but I am unable to figure out why. I have posted a scan file of a start up and idle.Pauls TA idle.hpl

  2. #2
    Tuning Addict 5FDP's Avatar
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    450mv on the o2 sensors is a dead give away that you have a wiring issue for both sensors. They are either unplugged or something in the wiring/fuse is wrong with them.

    Nothing in the tune can fix that, so don't look there.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  3. #3
    Did notice that, they are plugged in and fuse is good. The car has been previously tuned, is it possible that something has been changed to try and disable/ignore them? Just a thought, because the car runs surprisingly well for both 02 sensors to not be working.

    Thanks, Here is the tune file. Pauls ta made to match repository.hpt
    Last edited by nolan.kort@gmail.com; 5 Days Ago at 12:13 PM.

  4. #4
    Tuning Addict 5FDP's Avatar
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    No, closed loop is still active in the calibration and the sensors are not disabled.

    If you think it's a scanner fluke, remove the channels. Re-poll for supported parameters and add them back in while connected to the vehicle.

    Past that it would be looking for possible DTC codes and checking the wiring.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.