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Thread: idle/starting help

  1. #1
    Tuner in Training
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    idle/starting help

    the problem is the motor will not crank and run unless I hold the throttle while cranking. once it starts it will run fine with a good stable idle, now surging or idle hang. it will pretty much start and run when cold but once it is warm at all I have to push the skinny pedal. it fires up and dies right away without the throttle pedal. I have just about wore the starter out trying to tune it out. I have read and read but cant get it figured out. I have disconnected the iac and reset tps several times. if I use the screw on the tb enough to get it to crank on its own it idles at 1100. if I set the idle with iac unplugged it will not crank on its own. iac steps are around 40-50 warm and tps is within range. help please..

    the combo.. 68 Camaro drag car
    lq4, po1, 102mm holley tb, 210 bosch injectors, pretty big cam, 88mm turbo, e85, a2w, power glide. it was all tuned last week and made almost 900 to the wheels but I was told they all require a little throttle to start...
    it is a pain to climb over the roll cage to hit the throttle just to crank it. any help will be appreciated.thx
    Attached Files Attached Files
    04 5.3 with a built 4l60 3:73 9" in a 1935 chevy 2 door sedan.

  2. #2
    Tuning Addict 5FDP's Avatar
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    How much have you done with the base running airflow, idle timing and start up airflow or IAC settings?

    I'd also only allow the computer to do so much with the underspeed and overspeed spark corrections. The less you let it do the less it will idle hunt and spike the timing up and down making it much smoother.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
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    I have worked on all of the above until I am sick of it... anything stand out in the tune that could cause this issue?
    04 5.3 with a built 4l60 3:73 9" in a 1935 chevy 2 door sedan.

  4. #4
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    Man, none of you guys care to help a brother out?

  5. #5
    Advanced Tuner
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    Try adding 2 more grams of air to the hot temps that are giving you problems

  6. #6
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    Well, i have tried that among a ton of other things. I would love for someone to take the time to look at the tune file. I have gone up on air down on air, up on fuel and down on fuel. Timing etc etc... i feel like it is something simple i am missing because it runs perfect if i hold the throttle while cranking.

  7. #7
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    How much overlap on your cam @.050? And is this a 408c.i.?

  8. #8
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    Sbe 6.0
    Cam is 7.5

  9. #9
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    Your cylinder volume per liter is @ .83627= 408c.i. if it's a stock bore and stroke 6.0 it should be @ .74819. and that will screw up all your air calcs.
    Last edited by MarcusMilner; 10-16-2018 at 10:27 AM.

  10. #10
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    And sent you a pm

  11. #11
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    If i change that will it mess up the ve table? It is set up to 22lbs of boost and really dont wat to mess that up. Thanks

  12. #12
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    Yes it will, the tune thinks you have a 408, but you actually have a 366, right?

  13. #13
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    Yep 366. Well i will either have to live with it or somehow tune the idle around it. It idles like a champ now just have to give her throttle to start. Annoying

  14. #14
    Tuner in Training
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    So with the cylinder volume in the tune being set for a 408 what could I do to get her to crank on her own?

  15. #15
    you have to get it tuned correctly. You need a wide band and manifold size and engines size and start over from scratch. I hate to say it but if it was tuned wrong with e85 is absolutely notorious for cold start problems if not tuned right. I would take it to a local professional, Its stating you have 111 ftlbs of torque just to idle you seriously need it tuned right. Im sorry but its clearly not anywhere near correct

  16. #16
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    I am not buying that it cant be made to crank and idle as is. The tuner that worked on it made close to 900 whp and has perfect afr from idle all the way to 20psi of boost. Just the fact that i have to mash the pedal to get it to start is annoying me.