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Thread: 5.3 Swap....SOMEONE PLEASE HELP

  1. #21
    Tuner in Training
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    I noticed the timing seemed a bit odd as well. Any other ideas of things that would cause this

  2. #22
    Advanced Tuner IARLLC's Avatar
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    Well here is another guess. I am not an idle expert... but the drastic - timing numbers you get early on combined with the sharp increases and decreases...maybe under Spark>Idle Adaptive Spark Control>Overspeed the numbers on the far right are a lot more extreme than my 03 5.3. Yours is the same as mine up through 100rpm then at 150 your retards 2 more than mine, at 200 yours retards 10.5 more than mine, at 250 yours retards 18.5 more than mine, and at 300 yours retards 20 more than mine. It might be interesting to reduce those numbers by these amounts and see what happens. I could be wrong on that. Again the reduced rotating mass allows much quicker reactions from the internals than expected by the computer....so the every input would get a more drastic reaction...including rpm and thus spark...maybe. This is my basic line of reasoning with the lighter rotating assembly...and if correct this too will settle down once bolted to a converter....maybe

  3. #23
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    Anyone else?

  4. #24
    Tuning Addict 5FDP's Avatar
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    Random question, how many grounds do you have setup on this engine stand??

    Each cylinder head should be grounded and atleast 1 or 2 grounds on the block. I thought I remember reading somewhere that loose grounds on the back of the cylinder heads can lead to random electrical issues.
    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.

  5. #25
    Advanced Tuner IARLLC's Avatar
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    I second that. I have seen loose grounds on the back of LS1 heads cause all kinds of crazy issues. Totally worth checking...twice.

  6. #26
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    I am going through my grounds now. I have one from ground to battery. Another from battery to stand and the 3 harness grounds to the back of the block? Sound ok

  7. #27
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    I had a heck of a time getting my 5.3 runnin right. wound up being 5 stuck injectors.. pull fuel rails up so u can see injectors. unplug coil power wires so u don't have a fire. turn fuel pump on and spin the motor over. check that all injectors are spraying. I had an extra set laying around and 6 of those injectors were stuck. I built a plug and soaked them in carb cleaner beat them and sprayed carb cleaner through them and chattered them with the wires I rigged up and got 8 to work. If the motors sit for any length of time the injectors can stick. I am very new to hp tuners (last week) but I like to make sure the motor is right before the tuning starts. good luck

  8. #28
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    Update....... I am still having the same issue. I have built another harness to make sure i did not have a short somewhere giving me a problem, and it does the exact same thing. This thing only acts up at idle. It bounces idle 450-650 but when you idle it up the TPS sensor holds a steady %. When it sits at idle the TPS bounces all over the place. Jumping on the gas it revs up like you would expect. Random question.... will not having the VSS hooked up to anything give me these problems, since the motor is on a run stand. I have left the VSS sensor in the harness but obviously it is not hooked up to a trans. Is there a way to bypass this or am I thinking incorrectly