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Thread: Afterstart stalling issue

  1. #1
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    Afterstart stalling issue

    Could someone look at my tune and see if they can give me any suggestions. I had the afterstart stalling issue initially when I started dialing in the idle IAC tune. I fixed it by removing fuel from the 45-40kPa/800-1200rpm cells in the VE table since the motor passes through these cells after starting going to targeted idle rpm. My motor idles in the 50-55kPa/800rpm cells. Now that we are getting some cooler temps, the problem is coming back when it is cool out. Seems to be fine when temps are warm. My desired air numbers are in the low 50's to low 40's. After it makes it past startup when the temps are cool it is fine with no stalling issues.
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  2. #2
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    Doesn't anyone have some input on my issue? I did look at friction airflow but I would like some thoughts from you guys first. This is my first ground up tune and it has been a challenge but also very rewarding at the same time.

  3. #3
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    Idle airflow probably. How many times have you run the RussK idle config? Hopefully more than once, once isn't enough...

    If you have an issue in the first few seconds (up to maybe 7s) of running, then maybe the friction airflow as well.

    BTW your MAF curve will need smoothing also, although it's nothing to do with idle...

    kr D.
    99 TA, Texas Speed LS376, PRC heads, 233/239 cam, Fast 92mm, 95mm TB, card style MAF, Tick TR6060, Strange 4.11 12 bolt axle & clutchpack diff, Strano springs/dampers, Vette 18" wheels, Vette disks, CTS-V calipers, 16lb flywheel, long tube headers, no cats.

  4. #4
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    Thanks dermotw I have ran the RussK routine several times. Those numbers are very constant now and after the idle settles it is very stable. The stalling is in the first 7-10 seconds of run time when the intake air temp is in the 70's, so I will look at the friction airflow. Any thoughts on which way I should go with the numbers? Thanks for the help.
    Last edited by gnnova; 08-26-2016 at 10:10 AM.

  5. #5
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    Also thanks for looking at the rest of the tune. I smoothed VE table and since it is running so good in the rest of the tune I have not worked on the MAF smoothing yet. Thanks

  6. #6
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    Re friction:

    The wisdom is usually to increase the camshaft based delay to 25, (friction airflow delay), and reduce the decay vs. ECT (friction airflow delay) - mine is .050 or so and also varies across temp range for example, yours is set at .150.

    If it doesn't start so easily when hot then the startup airflow initial usually gets bumped up..


    kr d.
    Last edited by dermotw; 08-26-2016 at 02:34 PM.
    99 TA, Texas Speed LS376, PRC heads, 233/239 cam, Fast 92mm, 95mm TB, card style MAF, Tick TR6060, Strange 4.11 12 bolt axle & clutchpack diff, Strano springs/dampers, Vette 18" wheels, Vette disks, CTS-V calipers, 16lb flywheel, long tube headers, no cats.

  7. #7
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    Thanks dermotv Did you mean to say (friction airflow delay ) twice because it seems like you are taking about two different things and I did not see the setting you said that mine was set to .150. Sorry for asking about the clarification. I think I understand what your telling me but I want to make sure I understand before I make changes.