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Thread: General Tuning Order

  1. #1
    Carb and Points!
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    General Tuning Order

    I see FAQs and instructions on how to hook up Connectors, use BINs, XDF & ADX files but, I do not see any intro to tuning so, I thought I would ask here.

    What would be a recommended pattern to tune on a 1995 LT1 or any vehicle for that matter?

    This is a manual 383 with LE2 heads and CC503 cam.

    Based on data logging I have moved the BLM boundary to 40, 57, 85 MPa and 100, 1400, 2400 RPM.
    Also disabled EGR & air pump. (physically intact.)

    Based on some other websites I am considering to temporarily disable the MAF and do a first stage tune in Speed Density. The same poster also suggested disabling DFCO. I do see in my logging data that the 1, 2, 3 BLM Cells are almost empty. I assume that is because the ECU goes into cell 16 when letting off the gas. They then suggest going back and fine tuning MAF VE tables. ( I assume we are talking about the MAF Sensor Calibration Tables followed by a revisit of the VE vs RPM vs MAP. Correct?)

    I am thinking
    1) Main Spark advance ( Idle seems to draw 40 to 45 MPa vs the expected stock 35 MPa. Should I run peak advance along the 45 MPA column?)
    2) VE vs RPM vs MAP
    3) Crank VE vs %TPS vs RPM
    4) MAF Sensor Calibration Tables (Still using stock MAF and injectors now.)

    I understand that changing any area may have an effect on other areas. I am looking for a method that provides the most efficient tuning.

    I am open to suggestions of other areas I should be looking at as well as a recommended pattern even if it is in generalities.

  2. #2
    LT1 specialist steveo's Avatar
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    there's no pattern except that fuel is a bit of a stack, like injector constant, then VE or maf table, then adders (power enrichment) so you should tune in that order

    spark and fuel are related a bit but you might not even notice. i would tune fuel in cruising range then spark in cruising range then do another pass over fuel. you can slide spark up and down in real time in cruising range with eehack which is helpful because spark there is a 'by feel' thing.

    idle spark and idle speed is usually something people tackle early on just so it doesn't run like crap while they're playing with it

    VE is something that you don't have to do. so either don't do it or do it later when you're bored, it's definitely not where you do your 'first stage tune' unless you are planning on chucking the maf as it's more of a backup for when the maf dies.

    do you want to make decent power? power enrichment fuel and spark in the high KPA columns are where that happens, need a wideband to dial the fuel in there

    i have a lot of tools for that ECM, and some notes on my site especially about cleaning up closed loop with longer headers and stuff, might want to read over that

  3. #3
    Carb and Points!
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    Thanks for the reply Steveo,

    This powertrain was just installed in my 96 TA WS6. It has about 3000 miles on it now. I am using a 95' Fbody ECU & harness
    This engine (383 + T56) is eventually going in my 75' Vette. Based on historical data it seems that once the C2 & C3 Vettes get over 450 - 500 FWP other weak spots seem to show up, transmissions, axles, rear gears, etc. I just want the car to honor its heritage and am not looking to go 'All In' to fruitlessly try to keep up with C6,7,8s. LLoyd Elliot says this combo is good for around 490 FWHP. My engine builder said this combo would be about 525 FWHP. So, I am hoping to eventually see something in that range.

    I do have some goodies to add if needed such as larger injectors, 52mm throttle body, twin Walbro pumps, hotwire for the pumps, MSD Box. But, I only want to add such things IF the engine tells me it needs it. I have not purchased a WBO2 yet but plan to do so before getting over 5800 RPM.(Yeah, I know I'm leaving a lot on the table right now. I'm stopping there for now as my calculations show the stock injectors should keep up.) I also have access to a chassis dyno. I am going to do data logging/tuning to be reasonably close before getting on though.

    I also plan to change 1 thing at a time to avoid causing confusion.
    Re Idle: Currently set at 800. I did soften the idle overspeed/underspeed spark retard & advance vs RPM error. Seems to idle fine. I cannot hear any lope. It sounds stock to me. I have read that a bigger displacement motor will tend to swallow up some "lopiness" vs a smaller displacement for the same cam.

    I borrowed the Spark advance vs RPM VS MAP from a "95 Corvette LT1 6 Speed 4745.bin" file posted here for KPA above 60. I also moved the main spark advance ridge from 35 KPA to 45 KPA and smoothed. The car does seem to have a bit of knock around 2000 RPM if my daughter stomps the pedal and doesn't knock if I 'roll into" the pedal.

    I disabled the EGR based on the idea that an LT4 with Hotcam didn't come with them and the CC503 has more overlap than the Hotcam.
    Last edited by el Jefe; 1 Week Ago at 03:11 AM.

  4. #4

  5. #5
    Carb and Points!
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    Ok,
    Do you think Ford 32# ( maybe with a little higher pressure) will be enough or should I skip up to the 42#? Motor was built for NA, tighter ring gap. Never will see Nitrous or FI.

    I wanted to use the smallest that will get the job done with the idea to keep as good a control at lower RPMs as possible.

  6. #6
    LT1 specialist steveo's Avatar
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    if you are truly shooting for over 450hp you should just throw the 42lb injectors at it. a good quality properly configured injector will idle fine on an engine like that. i wouldn't use 32lb injectors on engines in excess of 400hp.

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