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Thread: TCC lockup on deceleration

  1. #1
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    TCC lockup on deceleration

    Hi guys,

    Been having some problems tuning a 14 f150 6r80. I am trying to keep the DFCO engaged while under deceleration because i like the "manual" feel that it gives under decel. Im having problems when the revs get down below about 1K RPM where it will command more torque and kick the fuel back on before downshifting then DFCO when it revs up a bit and the revs bounce up and down until it downshifts. I've found that I cant get my shift points high enough to keep drive-ability around town and have the truck downshift before the revs drop too low.

    I'm wanting to keep the TCC locked on deceleration in 5th and 4th gear, like it does in 6th to keep the revs up and DFCO engaged. I've tried lowering the TCC lockup to zero, but no matter what, it unlocks when i let off the gas in the lower gears. If someone could point me in the right direction to keep it locked up I would appreciate it. If it has to do with the TCC release > TPS tip out low/high, etc. how do these work and how is the delta torque at -4000?

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  2. #2
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    Attempted to change all the TCC release values to 10,000 or -10,000. No change. I chose those values for testing because thats what they are on the 2015 f150. Also played with unconditional unlock inder torque converter > general. Changed negative torque rate down to -2,000 to match the other values. Also didnt solve my problem. I'm also trying speed ratio for neg. slip, but its not looking promising.

    I did lower TCC steady state slip and TCC desired slip in the higher gears for less slippage while cruising. That seems to work, but it looks like the TCC never truly locks up, it always has a little bit of slip to it.

  3. #3
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    I'm on the same quest with my car. So far I have it staying locked most of the time and can drive it like a manual if I want with select shift. However, I want the TCC to stay locked after heavy accel , during heavy decel providing engine braking but it's not. It starts to at first then unlocks. I think I've found the setting and will test soon then report back.

    Tip-out rates are just that. A tip out is when you reduce the throttle. When you reduce it you are going negative relative to the previous position of throttle hence the -4000.
    Knock Retard is like a Horsepower Tax: (+) Knock Retard = Less Net Power, (--) Knock Retard = More Net Power.

    2014 Mustang GT Premium. VMP Gen2R Supercharged with an FTI 3000rpm Converter. JLT, BMR, Steeda, Viking, etc.
    Don't fix it if it ain't broken | Maximum effort gets maximum results

  4. #4
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    Bumping up the TCC Speed Ratio for Negative Slip has helped keep it locked on decel... sometimes. I have it bumped up to 1.150, originally it was .99. I log TCC speed ratio, TCC slip, and TCC desired slip. The desired slip raises on decel, not sure how to change that, until it hits the TCC Speed Ratio for Negative Slip set point. At that point, the converter unlocks and desired slip jumps to 1020 RPM. Changing that has mostly kept the converter locked through 5th, but if it happens to unlock, it will disengage DFCO and the RPMs will jump up a bit until it downshifts. Upping the TCC steady state slip in the gears you want to stay locked might help as well. That is the amount of slip allowed before unlock.

    Also, I get why the tip out rate is negative, just not sure why it is such a large number. A reduction of 4000 torque/second seems like it would be impossible.

  5. #5
    Advanced Tuner veeefour's Avatar
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    Quote Originally Posted by F150Farmer View Post

    I did lower TCC steady state slip and TCC desired slip in the higher gears for less slippage while cruising. That seems to work, but it looks like the TCC never truly locks up, it always has a little bit of slip to it.
    Because it never fully locks up...ford logic. TCC OPEN SLIP TABLES dictated the amount of slip while locked - OPEN for locked...ford logic.
    TCC slips ever so slightly while locked. Changing that values to 0 will help to lock it completely. It's there to help with NVH.

    The rest is up to APPLY/RELEASE tables.

  6. #6
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    Quote Originally Posted by F150Farmer View Post
    Bumping up the TCC Speed Ratio for Negative Slip has helped keep it locked on decel... sometimes. I have it bumped up to 1.150, originally it was .99.

    Also, I get why the tip out rate is negative, just not sure why it is such a large number. A reduction of 4000 torque/second seems like it would be impossible.
    My description says TPS tip-in or tip-out rate for those fields, not torque/sec.

    The problem I had was it would unlock at random (and even re-lock) on very light decel at highway speeds (1250rpm+ 50mph+). When I reviewed the log it seemed the converter was slipping intentionally (following stock settings) at those speeds and that made negative slip occur. When it would hit 1.00-1.01 on no throttle input it would just command the unlock.

    Sure enough I zeroed out ALL of the steady state and desired slip tables, and set Neg. Slip Speed Ratio to 1.10 and voila! Now it's rock solid in gear. I didn't have a lot of time to test more than a quick ride (cause of curfew here) but before and after data-logs were a substantial difference and 100% it worked.

    Also try Torque Based TCC Ctrl = Disabled (I set this too). What happens if you very lightly get off the throttle?

    At some point I'll go back and put some stuff back stock to see what the exact settings are because I have my full trans tune on this so a lot is changed and light years better than stock
    Knock Retard is like a Horsepower Tax: (+) Knock Retard = Less Net Power, (--) Knock Retard = More Net Power.

    2014 Mustang GT Premium. VMP Gen2R Supercharged with an FTI 3000rpm Converter. JLT, BMR, Steeda, Viking, etc.
    Don't fix it if it ain't broken | Maximum effort gets maximum results