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Thread: Cold start and closed loop question

  1. 07-10-2014 #1
    The Shop Inc
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    Cold start and closed loop question

    02 Camaro 4L80E segment swap. 102/102 throttle body and intake. 6.0l w/LS3 heads.
    Idle concerns.....Warm Its starts great, crusing and decel in gear are great. If in Park and free revving it will not come back to a stabilized idle. It goes from having follower airflow to no follower airflow very fast. I tried different combinations with decay and delay. I have the throttle blade set so that the idle steps are around 20 in park warm trying to get enough steps for cold start.
    Cold start........I cannot get it to start on its own for anything..If I hold throttle open about 8% it starts but will not hold a stable idle until it runs some. Im not sure if my running airflow is accurate when cold as I cannot get it to stay running.
    I have tried playing with steps/vseffective area. Honestly ive tried so much stuff im kinda lost.
    The other thing this car does which has me concerned is when in closed loop there is +/-10-14% difference bank to bank on LTFT. I tried changing location of the o2 sensors but its still the same. Ive been tuning it in open loop.
    any advise would be great.
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  2. 07-10-2014 #2
    The Shop Inc
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    Just found an intake leak. Im an idiot. I dont know why I didnt check into the difference in LTFT before. I suspect I will still have idle and starting issues but we will see after I fix the intake.
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  3. 07-10-2014 #3
    blownbluez06
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    Is your IAC wide open on startup? You don't seem to have much airflow commanded considering you're having trouble starting. Is your throttle showing 0% at idle? Have you done a TPS relearn?

    Disable LTIT's, Log STIT's. increase commanded airflow, watching IAC counts also increase startup and friction airflow for the initial startup event.
    Hsquared racing engines RHS 427, Procharger F2, Moran Billet Atomizer injectors, Alky Control,Mast LS7 heads, Nitrous outlet kit,Tilton quad disc clutch, DSS shaft, RKT56 ZR1 trans, RPM Quaife diff. Built and tuned by yours truly.
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  4. 07-18-2014 #4
    The Shop Inc
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    Thats where i get STIT to be 0. I used the idle airflow config. After fixing the vacuum leaks its way better for cold starting. Im curious though.. Not matter what I do I cannot get it to have throttle follower decay. It adds follower airflow but when I let off the accelerator it drops to 0 instantly. Which in turn causes the car to die.
    See the current tune and datalog of the follower airflow.
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