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Thread: Twin turbo GTO math perimeters for double stoich trick?

  1. 03-23-2017 #1
    milesg
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    Twin turbo GTO math perameters for double stoich trick?

    I have an 05 gto with a cx racing twin turbo kit installed. I am just starting the initial tuning for it but am having issues with logging AFR error. I have done the double stoich half inj flow trick because e40 pcms are the devil. But now i am commanding 27.87 and the afr error is thinking i am way to lean. the main problem is i am using a custom math perimeter to log my WB gauge through the pressure sensor since i do not have HPT pro. Is there a way to just half the expression? As of right now this is the expression i have inputted to read correctly. 100*((([7101.10]/.5)+9.4)-[50121])/[50121].
    Last edited by milesg; 03-23-2017 at 01:53 PM.
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  2. 03-23-2017 #2
    rbooth
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    If you tuned in lambda it would simplify things. You wouldn't have to compensate for the scale as commanded and actual would be 1 or whatever your commanded pe is.
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  3. 03-23-2017 #3
    milesg
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    I might have to go that route if there is no way to log AFR. Lambda is just unformiliar to me. Can I not just at a /2 in to the formula somewhere and divide by 2? I'm not to good at the math perameters.
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  4. 03-23-2017 #4
    GHuggins
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    Just halve all of the individual commanded pids in the formula. Don't half the whole thing. There's also a formula in the scanner section that compensates for changing stoic and alcohol that will work for this too. Just requires logging a couple more parameters is all.
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  5. 03-24-2017 #5
    milesg
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    To halve the individual commands where would you put the / (2)? I'm still not 100 percent with the formulas yet.
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  6. 03-24-2017 #6
    GHuggins
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    (Parameter /2)
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  7. 03-28-2017 #7
    GNXClone
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    I'm running FIC 104# injectors (@4 bar) with an E40 and because of this scaled by 50%. But I halved the engine displacement and the injector constant and leave stoich at 14.7.
    This has the side effect of doubling the range of the spark tables, which is handy since it's boosted. Less resolution in the table but that hasn't been an issue.

    If you're interested, one of my first scaled tunes is in the repository.
    https://www.hptuners.com/customers/t...wnload&id=1475
    2006 GTO, APS TwinTurbo, Stroked LS3 416ci, LSA heads, LS9 cam, 4L80e
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  8. 03-28-2017 #8
    GNXClone
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    Oh, the only reading this messes up is how much fuel is being consumed. It's actually using twice as much as it thinks. And the dash shows I'm getting twice the MPG I really am.
    AFR parameters are the same as a normal scanner config.

    ..and you can't cut-and-paste from other non-scaled tunes. You have to eliminate or interpolate every other row.
    Last edited by GNXClone; 03-28-2017 at 08:49 PM.
    2006 GTO, APS TwinTurbo, Stroked LS3 416ci, LSA heads, LS9 cam, 4L80e
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