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Thread: tuning LS4

  1. #1

    Question tuning LS4

    I'm currently helping a local tune his 06 impala ss ls4. I have dabbed in mainly fbodies and looking at the ls4 setup theres tons of more data and tables than I anticipated. in searching on here as well as other forums (ls1tech for example), a couple members mentioned "reduce the burst knock air delta table 10%". which table is that? I noticed a section call burst knock retard but I also see 3-4 fill in data followed by the one labeled something like aircyldelta and within that table has values that are whole numbers, meaning you cant enter anything with decimals.

    also regarding the spark advance. I noticed that when I was logging a WOT run, it was 28* with 2 degrees of KR at 0.68g, so in theory the car's trying to command about 30-31*. in the high octane table I noticed in the cyl airmass 0.68g it was set at about 34 degrees while in the low octane at about 23 degrees. IIRC the pcm would take the averages of the 2 tables which if correct is about right in the pcm trying to command 30-31 degrees. in the LS1 world, long as premium fuel is used, ppl have copied the high octane table into the low octane table. is this advisable for the LS4 as well?

    also the current stock PE enrichment is set at 1.21 or 12.15. aside from the 2* of KR which I imagine GM set the KR on the aggressive side, is it alright if I set the PE EQ to something like 1.18 or 12.5 after possibly lower the KR sensitivity a bit?

  2. #2
    Senior Tuner
    Join Date
    Mar 2011
    Location
    Ripley, MS
    Posts
    1,865
    30 degrees of ignition timing is just too much. Typically, a 93 octane tune will end up between 26-28 degrees at peak hp.
    I'd recommend adjusting the high octane table accordingly.
    For a street tune, Leave the low octane table at least 3-4 degrees lower than the high octane table.

    I'd start with a PE setting of 1.18 and then check it with a wideband.
    I'd leave the knock sensitivity alone on a mostly stock engine.

  3. #3
    that's what it shows as stock in his pcm.
    I gotta invest in getting a portable wideband with the attachment that clings to the tail pipe.
    regarding the HO table, I lowered the timing by 2 degrees from 3900-6400RPMS in the 0.62g to 0.80g since his only peaks at 0.68