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Thread: Help confirming octane on tune

  1. #1
    Tuner in Training
    Join Date
    Jul 2024
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    Help confirming octane on tune

    Very new to HP Tuners and tuning at all, recently picked up an LFX swapped Miata that was running E85 when I got it. I'm planning some road trips to the mountains where I can't get E85 and just want to confirm the fuel/spark map is fine for 93 octane. Engine does have MACE cams, a flex fuel sensor and a larger throttle body (80mm ported vs. stock 70mm), I downloaded the current tune on the car and attached it. The sensor is showing 65% ethanol, I'm pretty sure 93 (or even 87) octane would be fine, but don't understand enough about how the tune works and really don't want to screw this engine. Any help would be appreciated!
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  2. #2
    Tuning Addict 5FDP's Avatar
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    May 2012
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    Rogers, MN
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    I don't know that V6 platform very well as far as what is good for spark values but I know one thing for sure is that it is not okay to have both the high and low octane spark tables exactly the same. The way it's setup means that if there was knock retard, it can't reference the low octane spark table to use less timing. It will knock and pull that timing away but then as soon as the knock stops, it will slam all the timing straight back in it which is not what you want.

    The idea of the high and low tables is to use them both. It always runs off the high octane table until it shows knock, then will use the knock learn factor to interpolate the timing between the two tables depending on how high the KLF gets, then it will slowly return the timing to normal when the KLF goes back to normal.

    For the sake of being safe and not knowing how well the engine runs I would do the following. Highlight the entire low octane table and reduce the entire table by 10 degrees. I'd maybe even lower the high octane table a little too but those values might be totally safe.

    Also the IAT spark correction was zero'd out, that's not a good idea either. I would start having it pull timing above 100 degree air intake temps, start with 1 degree of timing and be pulling 5+ degrees with temps over like 140 degrees.
    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
    Tuner in Training
    Join Date
    Jul 2024
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    28
    Well shoot, I don?t have any HP Tuner credits yet but looks like I?ll need a couple. No experience tuning outside of old carb?d motorcycles and four-wheelers.

    I appreciate the input!