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Thread: Zf8 converter tuning

  1. #1

    Zf8 converter tuning

    Anyone have info on tuning the converter on these transmissions? The converter lock up table is a bit confusing to me.
    Also I?ve seen where people have set the shift nominal slip time down to .160 but on mine if I go anything lower than .330 it sets a check engine light. Any info??

  2. #2
    The converter clutch operates in one of 4 distinct modes. Open, Slip, Lock, and Overlock.

    Open: No engagement of the clutch at all.
    Slip: The clutch is engaged with a specific controlled slip RPM. I.e. 25RPM difference between turbine speed and input shaft speed.
    Lock: The clutch is engaged in an attempt to fully lock turbine speed and input shaft speed.
    Overlock: The clutch is completely engaged, i.e. converter clutch pressure is maximized.


    So, how does it decide which table to use?
    To start, your current shift pattern is mapped into a TCC pattern. Its then put through the lookup table with your current gear to give you a mapping.

    For example: (Your shift patterns may be named and in individual boxes, though we may be migrating that to a common style soon)
    yRivAAW.png

    So if we're currently in Shift Pattern 14 (a medium aggression normal shifting pattern usually), we will use TCC Pattern 9.

    Looking at the Pattern Map:
    dNf5CwK.png

    We can see that maps 11-18 are used based on our current gear.
    owQiWSW.png

    The values you see are the OUTPUT shaft speed of the transmission where various different TCC modes are commanded.
    For example, if we're in 2nd gear, we're using Map 12 on this vehicle. If we're at 50% APP,

    The converter will go from being unlocked/open to slip at 725RPM output shaft speed, and from slip to lock at 725RPM output shaft speed. I.e. the converter SKIPS the slip region, and goes straight from open to lock.
    If you look instead at 20% APP, you see the open to slip transition happens at 400RPM output shaft speed, and slip to lock at 425RPM output shaft speed.

    Overlock is at 10000RPM output shaft speed, that is, its unreachable, so its never commanded into this mode.

    As for transitioning back down, Over Lock to Lock uses a set offset from the lock to overlock transition, and lock to slip does as well.
    Slip to unlock/open is located in that table.

    AO4Jvg9.png

    So in this example, lock to slip would be at 425 - 100: 325RPM output shaft speed. However, slip to unlock is at 370RPM in this case, so unlock will already have occurred.

    Hopefully that makes the converter clutch operation a little more clear for you.

    As to the nominal slip times, this is the desired duration of the slip/inertial phase. The value you place in that table is used to create a turbine acceleration desired for the shift during that phase, and the transmission controller attempts to meet that target via a feedback regulated system during the shift.
    There's only so fast you can make this happen. You're restricted by the possible pressure that can be placed on the oncoming clutch, as well as by the inertia of the components themselves. The transmission adaptive routine is constantly learning corrections to hit those target slip times.

    I suspect the code you receive is from the adaptive system indicating that a given clutch element is slipping more than desired and it cannot fix it with its control bounds.
    If its not broke, just give it time.

  3. #3
    I appreciate the info!! These TCM seem very sensitive to changes lol. I am currently battling an issue with check engine light when trying to get my shift rpm to 6000rpm, if i set my shift scheduling in "normal" to anything higher than 5600rpm (based off of 6th gear output speed) than i get a check engine light. First gear will shift 5400ish than 2-3,3-4 shift right at 5600. Any suggestions for that? trans.png
    Last edited by Mass Motorsports; 06-10-2018 at 11:42 AM.

  4. #4
    Quote Originally Posted by Mass Motorsports View Post
    I appreciate the info!! These TCM seem very sensitive to changes lol. I am currently battling an issue with check engine light when trying to get my shift rpm to 6000rpm, if i set my shift scheduling in "normal" to anything higher than 5600rpm (based off of 6th gear output speed) than i get a check engine light. First gear will shift 5400ish than 2-3,3-4 shift right at 5600. Any suggestions for that? trans.png
    Do you know what code it sets?
    There is a parameter in Transmission > General dealing with a limp mode RPM limit, but without knowing what code in particular it sets, it's hard to make a claim one way or the other what could be causing it.
    If its not broke, just give it time.

  5. #5
    Advanced Tuner
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    Can you change the mapping data in the tables without causing issues? IE, set them all the same for a drag car?

    Or will that cause issues?

  6. #6
    Tuner in Training
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    shift schedule wise yes you can, however you can't change which tcc it decides to use , in my GC 2016 zf8 its usually 0 to 10 and 11 to 18 tcc maps
    But you can change the tcc operation as described above
    I have mine shifting 1/2 at a bit over 6k , so as not to allow an overshoot and bump the rpm limiter which is set at 6.6
    1st is quite low ratio wise on a GC srt and it gets there very quickly so an overshoot can happen
    If its the shift schedule your doing ,just multiply the output shaft speed by the gear ratio to give you the expected rpm =/- a bit for slip etc
    zf8 1= 4.71
    2 = 3.14
    3= 2.10
    4 = 1.67
    5 = 1.29
    6 = 1.0
    7 = 0.84
    8 = 0.67
    hope its of some use

  7. #7
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    I'm going to bring this back up top. I'm logging and seeing more than just 4 distinct modes. There is an apply fill, apply comp, slip SS, and maybe another that I don't recall at the moment. What controls these? Are they adaptive?

  8. #8
    Quote Originally Posted by spoolboy View Post
    I'm going to bring this back up top. I'm logging and seeing more than just 4 distinct modes. There is an apply fill, apply comp, slip SS, and maybe another that I don't recall at the moment. What controls these? Are they adaptive?
    There are still just the 4 main states, but there are many modes that occur while targeting those 4 states.
    The TCC Mode shows the state of the actual converter clutch pressure controller itself, which may be on some in between states or be a bit more specific.

    The modes you can see here are:
    Init - I doubt you'll have a chance to see this mode, its only during startup while it first loads it.
    Open - The clutch is empty, fully open.
    Apply Ramp - Clutch Pressure is being ramped to fill pressure
    Apply Fill - Clutch Pressure is steady to fill the clutch volume
    Apply Comp - Clutch pressure compensation is occurring (adapting the clutch volume)
    Slip SS - Clutch pressure is regulated to a target slip, with no dynamics occuring
    Slip - Clutch pressure is regulated to a target slip, with dynamics occuring
    Load Free - There is no load on the converter clutch, pressure is being held to just keep the clutches together
    Locked - The converter pressure is controlled to ideally have 0 slip, but can have up to 5rpm of slip. This is actually what "locked" is for almost all transmissions. Its an ideal state of 0 slip, but the pressure is actively being controlled to be the minimum necessary, so some minor slip happens. This is usually how all transmissions work, and the reason is to minimize pumping loss inside the transmission for maximum efficiency
    Overlocked - The converter pressure is set to target EXACTLY 0 slip by using an offset/maximum pressure. Instead of using closed loop regulation like normal Locked, this uses maximum pressure. This increases pumping loss of the transmission oil pump, so its only used when necessary to maintain efficiency.
    Lock to Slip - The converter is transitioning from a lock or overlock state to a slip state.

    There are two additional modes that can happen during Unlocked/Open operation, these are both used to test/verify torque converter operation without causing the clutch plates to ever come into contact.
    Open Pressure Ramp - Verifies that pressure can be controlled by the TCM at a set rate. If this fails, a code is set for torque converter clutch pressure control.
    Open Current Ramp - Verifies that the torque converter pressure control solenoid works correctly. If this fails, a code is set for TCC solenoid failure.
    If its not broke, just give it time.

  9. #9
    Advanced Tuner
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    Quote Originally Posted by Steven@HPTuners View Post
    There are still just the 4 main states, but there are many modes that occur while targeting those 4 states.
    The TCC Mode shows the state of the actual converter clutch pressure controller itself, which may be on some in between states or be a bit more specific.

    The modes you can see here are:
    Init - I doubt you'll have a chance to see this mode, its only during startup while it first loads it.
    Open - The clutch is empty, fully open.
    Apply Ramp - Clutch Pressure is being ramped to fill pressure
    Apply Fill - Clutch Pressure is steady to fill the clutch volume
    Apply Comp - Clutch pressure compensation is occurring (adapting the clutch volume)
    Slip SS - Clutch pressure is regulated to a target slip, with no dynamics occuring
    Slip - Clutch pressure is regulated to a target slip, with dynamics occuring
    Load Free - There is no load on the converter clutch, pressure is being held to just keep the clutches together
    Locked - The converter pressure is controlled to ideally have 0 slip, but can have up to 5rpm of slip. This is actually what "locked" is for almost all transmissions. Its an ideal state of 0 slip, but the pressure is actively being controlled to be the minimum necessary, so some minor slip happens. This is usually how all transmissions work, and the reason is to minimize pumping loss inside the transmission for maximum efficiency
    Overlocked - The converter pressure is set to target EXACTLY 0 slip by using an offset/maximum pressure. Instead of using closed loop regulation like normal Locked, this uses maximum pressure. This increases pumping loss of the transmission oil pump, so its only used when necessary to maintain efficiency.
    Lock to Slip - The converter is transitioning from a lock or overlock state to a slip state.

    There are two additional modes that can happen during Unlocked/Open operation, these are both used to test/verify torque converter operation without causing the clutch plates to ever come into contact.
    Open Pressure Ramp - Verifies that pressure can be controlled by the TCM at a set rate. If this fails, a code is set for torque converter clutch pressure control.
    Open Current Ramp - Verifies that the torque converter pressure control solenoid works correctly. If this fails, a code is set for TCC solenoid failure.
    Thanks a ton Steven!

    I'm going to throw out another post about tuning the actual shift timing and clutches under the shift pressures tab. I hope you can help out there as well.