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Thread: Please analyze/review my current tune!!!

  1. #1
    Potential Tuner
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    Please analyze/review my current tune!!!

    Hey all,

    Brand new user here...never tuned before, and just plugged in the HPT unit a few mins before posting this! The car is new to me, but already had some mods done, and was tuned by a shop in SoCal via HPTuner. I'm wondering if there's any room for tweaking things at all as I begin to learn how this all works. I also run higher octane fuel than what it was tuned for, and opened up the exhaust slightly. I'll try to post all relevant info below. If I forget anything, let me know and I will get you the info quickly. Thank you in advance!

    Car:
    2003 Corvette Z06

    Engine:
    Gen4 LS3 (built by American Heritage Performance)

    Mods/Hardware:
    91 octane fuel (CA car)
    GMPP ported heads, 275cc
    BTR dual valve springs, Ti retainers (.660")
    Comp cam (226/238, .627"/.627", 113 LSA)
    Stock LS3 intake, ported and radius rod-modded
    Stock LS2 throttle body, ported to 92mm (Peak Speed Shop)
    AR long tubes, gutted cats (1 3/4")
    Stock C5Z axle-back
    Stock C6 LS7 MAF and air intake/bridge with K&N

    Current Tune:
    For the above mods/fuel, tune by Church Auto in Wilmington, CA
    Dyno was 493whp/463wtq
    (tune attached below)




    ...as I said, the changes since purchasing are very minor, but I want to tinker and learn how the changes affect things...
    Changes since purchasing:
    1) I run 94 octane fuel instead of the previous 91, so I am wondering if I can bump the timing advance a little?
    2) Changed the axle-back exhaust to freer-flowing, straight-through "bullet" style mufflers

    *3) Not done yet, BUT, I have purchased a full 4" air intake with a 4" MAF tube, and I am looking for info on how to adjust the MAF tables for the new tube*


    ...that's about it! Please let me know if this tune looks typical, and/or if there are any advisable changes for the new fuel octane or anything else. Thanks so much!
    Attached Files Attached Files
    Last edited by PNW_C5Z; 02-26-2020 at 05:42 PM.

  2. #2
    Advanced Tuner Lakegoat's Avatar
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    I would not be bumping up the spark tables. You need to lower the values in the low octane table by at least 4 degrees.
    2005 GTO, TrickFlow 225, Magnuson 2300, 4L80, 4 link 8.8
    2013 Silverado 5.3, 6L80

  3. #3
    Potential Tuner
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    Quote Originally Posted by Lakegoat View Post
    I would not be bumping up the spark tables. You need to lower the values in the low octane table by at least 4 degrees.
    Really? Almost everything I've read on here and elsewhere says that the common method is to make sure the high and low tables match?

  4. #4
    Tuning Addict 5FDP's Avatar
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    How would the computer pull timing if it did knock then?

    If both tables are exactly the same and there was a knock event, it could pull that amount of timing then it would go away and slam the timing right back in and it could knock again. Having less timing in the low octane tables allows the computer to use the knock learn factor to blend the timing between the high and low if there is knock retard.


    The only time timing should be the same is if you are using a stock operating system and you have to tune speed density with the MAF failed, as that will revert to the low octane table in that case. Upgraded OS's allow you to retain the high/low functions like a stock OS does.

    More timing doesn't mean more power. A dyno would tell you where peak power/torque is. Your timing is already in the upper 20's, going to 30-32 degrees could very well lose you power.

    Do your changes and get a wideband in the exhaust as well as that into your logs so you can watch real time air fuel ratio's. Create a wideband error for the commanded against the actual AFR/Lambda and you can start fixing the MAF curve because of your changes. That error graph will tell you exactly how much you need to change it.

    Wideband tuning is done in open loop with closed loop and fuel trims disabled too.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  5. #5
    Advanced Tuner mbray01's Avatar
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    My concern is that the knock sensor tables havent been lowered. Everytime ive ever done a gen 4 engine in a gen 3 setup, it has required the knock sensor sensativity to be increased by about 25%.
    Every one i have ever done had the engine rattling like marbles in a coffee can long before it detected knock. The high table looks good for 93, i would lower the low table about 4-6 degrees. Increase knock sensor sensativity till you see it pull timing at the current timing level, then back it down just a touch. Other than that i dont see much to really complain about with a quick glance
    Michael Bray
    Rusty Knuckle Garage
    Slidell, Louisiana
    15yr Master Tech.
    Custom Car Fabrication, Customization, High Performance.
    GM World Class Technician
    Shop Owner

  6. #6
    Potential Tuner
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    I've done a little bit of logging since posting, and there's been 0 timing pulled at any point from knock. It also seems to be running a bit on the rich side. That led me to believe I might be leaving something on the table there, but I'm going to take it to a well-recommended tuner and have them dyno tune it for the current conditions and see what changes they makes based on what they're seeing. Turns out a PO had wired in the WBO2 to pin 55 of the PCM which is a pretty common thing, so now I've got EGR voltage turned on in the scanner. Really hope I can break that mythical 500whp threshold I'm rubbing up against!

  7. #7
    Advanced Tuner mbray01's Avatar
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    THE FACT THAT THERE IS ZERO TIMING PULLED LEADS ME TO BELIEVE THE KNOCK SENSOR CALIBRATION NEEDS TO BE ADJUSTED. IT COULD BE THAT THE TIMING IS JUST RIGHT, BUT I ALWAYS LIKE TO SEE KNOCK SOMEWHERE, TIP IN, WOT, DURING SHIFTS, ETC. WHEN I SEE KR, IT TELLS ME THE SYSTEM IS WORKING, I WOULD RATHER IT BE A LITTLE AGGRESSIVE, THAN NOT AT ALL. I JUSUALLY LIKE TO FIND MBT ON THE DYNO, AND JUST HAVE IT TOUCHING THE KNOCK SENSORS AT THAT POINT.

    JUST THIS PAST WEEK, I DID AN LS3 IN A 2002 CAMARO, HAD TO INCREASE SENSATIVITY 45% to get it to register kr at 31 degrees, which is high for an ls3
    Michael Bray
    Rusty Knuckle Garage
    Slidell, Louisiana
    15yr Master Tech.
    Custom Car Fabrication, Customization, High Performance.
    GM World Class Technician
    Shop Owner

  8. #8
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    Being a bit rich won't lose much power and is on the safe side. LS engines don't need nearly as much ignition advance as old school engines but they do like what you can give them. I'm no help on Gen 3 -> 4 knock sensor calibration so if it was my motor, I would hesitate adding ignition advance until I was *sure* I could trust the knock sensors to detect knock.
    '66 Chevelle w/ 6.2L LSA block, crank, and heads; Carrillo rods; 9.5:1 CP pistons; LPE GT9 cam, E-Force, E67 ECU; LT headers, T56 Magnum