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Thread: Newbie, new 5.3 swap, high idle, running rich

  1. #1
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    Newbie, new 5.3 swap, high idle, running rich

    rons baseline white truck.hpt
    Rons truck baselline first run opertating temp.hpl
    ron.jpg


    5.3 swap into 1990 chev truck
    Background info, neighbor had a shop install an LS in his 1990 chevy truck. He gets deployed, truck sits, he returns from deployment shop says they went out of business. Fast forward 5 years. I say let?s look at it. Wiring is a mess, but it is an aftermarket harness, nicely labeled. I install a fuel system, run some power, get it to crank, and after adding a few grounds here and there it runs.
    It will crank and sputter a few times, and then fire up, super high idle, popping out the exhaust, and finally after about 30 seconds or so it?ll settle down into a 700-900 rpm fluttering idle.
    If I press the accelerator it?ll jump up to 6k with no effort, and then again settle down to the erratic idle.
    I?m a newbie to hptuners, so still learning the lingo and whatnot. I am not a newbie to tech stuff.
    I have found no vacuum leaks, looks like all the sensors are working correctly, o2s seem to be doing their job, I can?t get this to idle.
    The previous place did a ?mail-order? tune and ive looked through it and don?t see anything out of the ordinary.
    Fuel pressures are correct.
    Wiring/grounds all seem to be correct.

    Please any suggestions greatly appreciated.

    Thank you,
    -james

  2. #2
    Tuning Addict 5FDP's Avatar
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    The tune is still technically setup for a 4.8 engine, the cylinder volume matches that of a 4.8. Not a huge deal but should be changed.

    Is the vehicle still using the DBW throttle body and pedal from the donor truck??

    Stock engine, stock intake, stock injectors still???
    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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    Quote Originally Posted by 5FDP View Post
    The tune is still technically setup for a 4.8 engine, the cylinder volume matches that of a 4.8. Not a huge deal but should be changed.
    --original computer/engine/trans/DBW pedal?I wrote 5.3 but it?s a 4.8

    Quote Originally Posted by 5FDP View Post
    Is the vehicle still using the DBW throttle body and pedal from the donor truck??
    --yes all parts are from donor

    Quote Originally Posted by 5FDP View Post
    Stock engine, stock intake, stock injectors still???
    --LS1 style intake and injectors, headers, 3? exhaust

    engine.jpg

  4. #4
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    :bump:

  5. #5
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    Was a cam done or anything else changed?
    Last edited by race4beer; 10-20-2016 at 04:27 PM.

  6. #6
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    Quote Originally Posted by race4beer View Post
    Was a cam done or anything else changed?
    stock long block. stock heads/cam/springs/ etc

    headers, LS1 intake, stock LS1 injectors.

  7. #7
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    Get a tune from the repository your certain is actually stock unaltered. Then Compare your airflow tables base running airflow, throttle follower and throttle cracker. See what the mail order tune changed. This If your certain it's not a mechanical issue or vacuum leak.

  8. #8
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    Quote Originally Posted by Oleblu View Post
    Get a tune from the repository your certain is actually stock unaltered. Then Compare your airflow tables base running airflow, throttle follower and throttle cracker. See what the mail order tune changed. This If your certain it's not a mechanical issue or vacuum leak.
    thank you for the reply