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Thread: tune changes overnight

  1. #1

    tune changes overnight

    so ive been tuning on my 2014 ss sedan ls3 btr stage 2 n/a for a while now dialing it in here and there and have got it to behave pretty good now to where my wife even said that she likes the way it runs now. My problem is this morning when i took my daughter to school it changed like started to dip too far down at idle coming to a stop and lunges forward. Now the night before it was running great and i was thinking to myself that it was good and im the one who parked it in the garage and was the last to drive it. The tune is the same but its running different. This is not the first time either i just thought i was trippin but now im certain. The weather would not make the car jump forward like this. It is the timing im suspecting. Any ideas? It is the same table as night before. It just seems like it changes on its own.

  2. #2
    Senior Tuner TheMechanic's Avatar
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    The tune won't change on its own. Atmospheric changes that are a modifier that you are experiencing can do this. Just as you would do with a non tuned vehicle try to look at every variable so you can re-create the concern. Then log a good run. Compare the two. Specifically gear changes, TCC lockup, fuel P/W, STFT, LTFT, and of course timing. Its there you just haven't found it yet. The key to diagnosis is re-creating a concern.

  3. #3
    Potential Tuner
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    I'm curious what you found to be the cause? I'm going to be in a similar setup soon and will be tuning an LS2 with LS3 heads and a stage 2 BTR cam.