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Thread: 2014 Corvette Stingray Stock Tune VS ProCharger's Tune (comparison)

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    Default 2014 Corvette Stingray Stock Tune VS ProCharger's Tune (comparison)

    Hi all,

    I had the fortunate opportunity to install a ProCharger kit on a new 2014 Corvette Stingray. Having experience working on all model Corvettes, I am happy to say the C7 is by far the easiest model to work with yet. Everything is simple yet sophisticated, it was a very straightforward process. I have attached both the stock tune file and ProCharger's tune file for anyone who is interested in dissecting the E92 controller/tune. I have some questions based on what I am seeing in comparing the files:

    2014 Stingray Stock.ctz
    2014 Stingray ProCharger Tune.ctz

    1.) It appears as if the VVE tables have remained unchanged and the supercharger option has not been selected. What is this engine controller looking at to determine it's fueling?

    2.) The MAF table was scaled back, a lot... Wouldn't the added air being forced into the engine mean the MAF should be scaled higher?

    3.) The AFR was leaned out to 12.7, being forced induction, isn't this too lean? Maybe the direct injection system calls for a leaner AFR.

    4.) What exactly is "commanded power mode, A, B, and C"?


    That's all, feel free to discuss!

    Thanks
    2002 Z06
    Vengeance Racing Stage 5, H/C/I/3.90 diff, 575 hp
    2016 Chevy SS M6 (daily driver)
    Roto-fab Intake

  2. #2
    Lifetime Member swingtan's Avatar
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    1: If it's using the MAF, it won't use the VVE under boost conditions.
    2: and 3: It all depends on what the exhaust AFR is. Commanding specific ratios does not actually mean that's what the engine is using. Stick a wideband in the exhaust and see what the engine is really using.
    3: Command torque is the way of the future. The ECM maps the pedal position to a "desired torque" value. Then it uses the torque estimation tables to work out how much throttle is needed to proved the desired torque and opens the throttle to the required amount. This is good as it allows for changes in fuel types (spark blending moving from high to low tables), barometric pressure, air temps etc. So it makes the car feel more "constant" over a wide range of operating conditions. It's bad in that it messes badly with modifications as the torque model changes with each mod.

    Without seeing any log data, I'd suggest that the ProCharger tune is a "base" tune and is meant to be a starting point for more work.

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    Quote Originally Posted by swingtan View Post
    1: If it's using the MAF, it won't use the VVE under boost conditions.
    2: and 3: It all depends on what the exhaust AFR is. Commanding specific ratios does not actually mean that's what the engine is using. Stick a wideband in the exhaust and see what the engine is really using.
    3: Command torque is the way of the future. The ECM maps the pedal position to a "desired torque" value. Then it uses the torque estimation tables to work out how much throttle is needed to proved the desired torque and opens the throttle to the required amount. This is good as it allows for changes in fuel types (spark blending moving from high to low tables), barometric pressure, air temps etc. So it makes the car feel more "constant" over a wide range of operating conditions. It's bad in that it messes badly with modifications as the torque model changes with each mod.

    Without seeing any log data, I'd suggest that the ProCharger tune is a "base" tune and is meant to be a starting point for more work.
    What does the ECM look at to determine its fueling?

    That's interesting about the commanded torque. So the throttle/gas pedal is no longer a direct tie to the throttle blade, but more of a power commander.
    2002 Z06
    Vengeance Racing Stage 5, H/C/I/3.90 diff, 575 hp
    2016 Chevy SS M6 (daily driver)
    Roto-fab Intake

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    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by n8dogg View Post
    What does the ECM look at to determine its fueling?
    ...
    Other than Closed Loop, see Fuel->Open Loop and Fuel->Power Enrichment.

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    Quote Originally Posted by joecar View Post
    Other than Closed Loop, see Fuel->Open Loop and Fuel->Power Enrichment.
    So the E92 is fast enough to accurately fuel the engine without any airflow model?
    2002 Z06
    Vengeance Racing Stage 5, H/C/I/3.90 diff, 575 hp
    2016 Chevy SS M6 (daily driver)
    Roto-fab Intake

  6. #6
    Lifetime Member swingtan's Avatar
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    Fast enough?

    It's fast enough to calculate the VVE on the fly as well as the torque model and control the throttle..... It's not too much work to read the MAF and calculate the injector timing.

    Personally, I think the main use of the VVE in the factory tune is to provide a secondary fuelling model in the event of the MAF failing.

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    Wow, OK, you learn something every day!
    2002 Z06
    Vengeance Racing Stage 5, H/C/I/3.90 diff, 575 hp
    2016 Chevy SS M6 (daily driver)
    Roto-fab Intake

  8. #8
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by n8dogg View Post
    So the E92 is fast enough to accurately fuel the engine without any airflow model?
    It always calculates cylinder air first, even when CL/trimming.

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    Most Gen IV custom tunes / dyno tunes / etc. are setup in MAF only mode. EFILive is the only tuning software with native VVE tuning ability. That said, properly tuning the VVE is a labour intensive exercise - worth the effort to the enthusiast, but difficult to make commercially viable sometimes.

    Dyno tunes generally range from $600 to $1000 - and will be setup in MAF only mode. These work OK, but in my opinion they are not as "crisp" as a well tuned blended VVE and MAF (OEM style) setup.

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    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by swingtan View Post
    ...

    Personally, I think the main use of the VVE in the factory tune is to provide a secondary fuelling model in the event of the MAF failing.
    Hi Simon,

    Yes, I agree, the MAF is used as the primary airmass model, and the VE/VVE is used when the MAF fails, and VE/VVE is used during throttle/airmass transients

    ( notice that I'm calling it airmass model rather than fueling model )

    and it also seems to me that the VE/VVE is used to sanity check the MAF: if the MAF is causing the airmass model to significantly differ compared to VE/VVE, then it runs from VE/VVE until the MAF can be trusted again.

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