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Thread: Fast 102/102 TB help 99 c5 corvette stock ecu

  1. #1

    Fast 102/102 TB help 99 c5 corvette stock ecu

    Ok guys i need some help. I have a 99 c5 corvette its a 383 stroker stock ecu car. I had been running the fast 92 with the ls2 throttle body and the car has been running perfectly fine, i just put a fast 102 with the new Texas speed and Performance 102 throttle body, which looks exactly the same as the NW 102, and now the car is throwing a few codes. Accelerator pedal position sensor code, throttle body position sensor code and a correlation code.
    I really just need help on where to change some parameters around to get it to work.

  2. #2
    Scalar and re-tune. Goodluck

  3. #3
    Thank you, gonna rescalar and see if that helps out in the morning. Would you happen to know the calculation to convert the scalar for the 102 from the 92

  4. #4
    Senior Tuner cobaltssoverbooster's Avatar
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    i want to say its something like 82% = max bore area so max rotation / max area = new scalar.
    82%/7147mm^2=.01147

    i might be wrong. if you have a Area Scalar that asks you directly for the bore mm^2 then you would just input 7147 for a 102mm tb.
    can i get a second users verification on this?
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  5. #5
    Senior Tuner cobaltssoverbooster's Avatar
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    stock c5 bore is 78 mm so convert to area i get 4778.36mm^2. times this by .0255 and i get 121.848
    if you want to duplicate this result with a new area then you divide 121.848 by the new bore area of 8171.28 (102mm) and i get a value of 0.0149.
    this is also very close to my original value estimation so i would assume here the etc area scalar conversion constant would be between 0.0115 and 0.0149 split difference and call it 0.0132.
    the error in this conversion factor would technically be absorbed into the raf and other idle adjustment tables.
    rdrfabrication@gmail.com
    2016 GMC 3500 Denali Diesel
    2000 Ford Mustang - Top Sportsman

    Ecotec help can be found here:
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    LSJ-http://www.hptuners.com/forum/showth...965-LSJ-Guides

  6. #6
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    If it helps I'm at .0140 using a formula that will subtract the shaft size from the area. That being [(TBDiameter/2)^2 * pi] - [TBShaft * TBDiameter]

    I have searched this myself and it seems though that scalar number is all over the board for others that work well for them.

  7. #7
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    So, yes I agree with cobalt on this one. You will need to tune afterwards.

  8. #8
    so i changed the scalar numbers and it still has a reduced engine power code and all those other codes

  9. #9
    Senior Tuner cobaltssoverbooster's Avatar
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    What are the code numbers?

  10. #10
    Advanced Tuner mbray01's Avatar
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    on some vehicles using a 102, i have had to limit the throttle opening to 82% to keep it happy
    Michael Bray
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  11. #11
    Senior Tuner cobaltssoverbooster's Avatar
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    ive been sitting on this for a day or so now and came to a conclusion on personal opinion for the scalar value. the second calculation i made uses the area of the throttle body multiplied by the scalar to calculate an endpoint number. the computer would use this end point number for determining tb rotation.
    if i want that relationship to remain the same, then the new tb volume time some constant conversion number would still need to equal the same constant as the oem. so what is considered proper? well in personal opinion proper would be taking overall bore area and subtracting shaft area as mentioned. my personal conclusion tells me to use these formulas.

    [(pi/4)*factory tb bore diameter - (factory tb bore diameter * factory tb shaft diameter)] * Factory Scalar = Constant (x)

    New Scalar = Constant (x) / [(pi/4)* New tb bore diameter - (New tb bore diameter * New tb shaft diameter)]

    i choose this since as stated it compares true tb areas and also maintains the oem area to desired rotation output.

    As mentioned the tb bore is effectively at its maximum opening when the angle is equivalent to 82% of its rotation. This is due to the fact that the tb shaft diameter is larger than the blade thickness which allows it some rotation error before the blade starts to protrude and block more area than the shaft does. That is why you can reduce the max angle and still have same performance.

    I am sure this assumption has been made but i thought it would help people see what i was thinking about. the real number is likely closer to the .014 value but without shaft diameters then its hard to say exactly. the other tables in the ecu will still have some washout effect in masking any error in this value but at least you can sleep easy knowing the value is very close to what the dynamic model would require.
    rdrfabrication@gmail.com
    2016 GMC 3500 Denali Diesel
    2000 Ford Mustang - Top Sportsman

    Ecotec help can be found here:
    LNF-http://www.hptuners.com/forum/showth...357-LNF-Guides
    LSJ-http://www.hptuners.com/forum/showth...965-LSJ-Guides

  12. #12
    Quote Originally Posted by cobaltssoverbooster View Post
    ive been sitting on this for a day or so now and came to a conclusion on personal opinion for the scalar value. the second calculation i made uses the area of the throttle body multiplied by the scalar to calculate an endpoint number. the computer would use this end point number for determining tb rotation.
    if i want that relationship to remain the same, then the new tb volume time some constant conversion number would still need to equal the same constant as the oem. so what is considered proper? well in personal opinion proper would be taking overall bore area and subtracting shaft area as mentioned. my personal conclusion tells me to use these formulas.

    [(pi/4)*factory tb bore diameter - (factory tb bore diameter * factory tb shaft diameter)] * Factory Scalar = Constant (x)

    New Scalar = Constant (x) / [(pi/4)* New tb bore diameter - (New tb bore diameter * New tb shaft diameter)]

    i choose this since as stated it compares true tb areas and also maintains the oem area to desired rotation output.

    As mentioned the tb bore is effectively at its maximum opening when the angle is equivalent to 82% of its rotation. This is due to the fact that the tb shaft diameter is larger than the blade thickness which allows it some rotation error before the blade starts to protrude and block more area than the shaft does. That is why you can reduce the max angle and still have same performance.

    I am sure this assumption has been made but i thought it would help people see what i was thinking about. the real number is likely closer to the .014 value but without shaft diameters then its hard to say exactly. the other tables in the ecu will still have some washout effect in masking any error in this value but at least you can sleep easy knowing the value is very close to what the dynamic model would require.

    Maybe we can continue this thread with more answers? Have this 97 C5 with 6.0 donor motor with LS3 top end and 102 TB Intake combo. Have changed it to 82% which has made the REP go away but now has weird issues like transient lean off idle/stop from 1st-2nd......Then while cruising steady state and let throttle off it feels like wants to stop(Throttle shutting??) WOT seems very slow reacting now. I have alot more fueling to do but look at the BRA is now through the roof now and STITs. Its on a OL/MAF tune for now till O2s come in. Final tune will be OL from 0-1600rpm via PE enrichment and then CL on up/MAF. Commanded TPS and Actual not even close nor Accel pedal at floor says like 30-40

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  13. #13
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    I found this thread, but yeah i got lotsa questions and no answers LOL https://forum.hptuners.com/showthrea...-Scalar-tuning