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Thread: Cooling fan stumble

  1. #1
    Tuner in Training
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    Aug 2017
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    Cooling fan stumble

    Been playing around with this tune for a while. Spend more time reading all the stuff available on this forum and trying to learn to apply it then tuning. Been able to work through most things but this particular issue is giving me fits and can't seem to find much detail to help. My idle is steady at 900 rpm until the cooling fan turns on. Then AFR goes to 20 and IAC steps go up. Once the fan shuts down all is happy again.
    I am working on a 4.005" bore 4" stroke lq4 with a comp cams 54-454-11 cam (59* overlap).
    .614 intake 277 degrees
    .624 exhaust 293 degrees
    102mm throttle body
    No cats
    Long tube headers
    Three inch full exhaust
    48lb injectors at 58psi
    On the attached scan the area with high afr is with the fan running. Once it shuts down the idle and afr return to normal.
    I have attached my current tune.
    Any help on this is much appreciated.
    Attached Files Attached Files

  2. #2
    Tuner in Training
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    Aug 2017
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    No one has an answer for this or experienced the same issue. I am sure I have a setting off somewhere just need some assistance finding and correcting. And if someone wants to look through my tune and give me some feed back it would be appreciated.

  3. #3
    Advanced Tuner IARLLC's Avatar
    Join Date
    Aug 2016
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    942
    Under Idle>Airflow on the bottom/left you will find Cooling Fan Airflow. Factory e-fan trucks use 2.0 lb/h for fan 1 and 4.4 lb/h for fan 1/2. That is what I put in my e-fan conversions and it helps stabilize the idle when the fans come on.

    There is some minor chance that your fans are taking up electricity needed for the coils/injectors/O2 sensors etc. I would check that you still have adequate voltage everywhere when the fans come on. You might need to fix a ground or upgrade an alternator or something like that if the fans are actually affecting how the system mixes fuel.

  4. #4
    Tuner in Training
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    Aug 2017
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    Thank you for the input IARLLC. I will give the settings a try. Voltage does appear to be holding steady. I was thinking along the same lines on a voltage issue but holding steady at 14V or so.