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Thread: Post startup STIT

  1. #1
    Potential Tuner
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    Post startup STIT

    I've got a 2004 C5 with a P59 ECU running in with a I/H/C setup. Camshaft is a 224/228-113+4 w/ .603/.595". Car is pretty well dialed in and has no issues in startup or driveability. However, I'm interested to learn more about the STIT activity in the 30 sec or so post startup. Is this activity "normal" or expected? or is it indicative of something I can work on within the tune?

    2004Z06Enh_11272023.hpt 112720123 Idle As Found.hpl

    11272023 Idle.png

  2. #2
    Tuning Addict edcmat-l1's Avatar
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    Looks normal. It's a cold start at 37 degrees. It needs to add airflow. The "spike" is gone in a matter of seconds and it settles into a slightly negative trim. That's pretty much what you want.

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  3. #3
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    No fuel trims on a cold start until it reaches the Closed Loop Enable temp, which in your file is 93*F, which is probably a bit before it's warm enough to be ready. 130* or so usually works better.
    Quote Originally Posted by SiriusC1024 View Post
    I think they're junkyard rebuilds.

  4. #4
    Tuning Addict edcmat-l1's Avatar
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    Quote Originally Posted by blindsquirrel View Post
    No fuel trims on a cold start until it reaches the Closed Loop Enable temp, which in your file is 93*F, which is probably a bit before it's warm enough to be ready. 130* or so usually works better.
    Think he's talking about idle trims.

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