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Thread: Toyota Repository

  1. #41
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    Quote Originally Posted by SlowNStock View Post
    Increasing the rev limit is straightforward, it's under "Engine -> Fuel -> Cutoff, DFCO", just increase to the value you'd like. Don't go crazy on the stock valvetrain...



    As far as the 2-3 shift - couple things to be done.

    Per your attached file, I see you've dropped your 2-3 shift in Normal and Tow/Haul, you should also drop those corresponding values in the "Cold" and "Fault" tables as well.

    If the truck still shifts too high, multiply by the ratio of target/actual. In this case, with a target shift of 5800 and an actual shift of 6100, you have a ratio of 5800/6100 or ~0.95, multiply your WOT shifts by this figure, and smooth into the remaining as you see fit.



    I've made those hypothetical changes in the attached as an example - rev limit is raised to 6400, WOT shift points dropped by 5%, and the resulting shift scheduling copied over to the "Cold" and "Fault" tables.

    Example file: Attachment 97869


    A word on your log - you'll want to pare down the channels for the specific task at hand, having the whole kit and caboodle is fine to take a high-level look, but for something like this the net polling interval is a bit slow to get an accurate picture (I realize that's probably my fault for not putting more explanation in my earlier posts). Here's an example of a smaller set of channels with better polling intervals, if you do a log with both you should notice the difference right away (you may need to fine tune polling intervals further): Attachment 97871


    Thanks @SlowNStock. I managed to amend the shift points, which are honestly not my ultimate goal.

    1-2 shift is remarkably better after making it to shift earlier.

    However 2-3 is still not smooth. The shift is hard and makes the truck to stall. I also noticed that ignition timing goes to Zero at 2-3 & 3-4. Is this normal?

    I have reached HP Tuners support again today requesting for torque management tables. Here is the response:" the shift pressure and trans torque management parameters aren't visible it means that we don't have the slave CPU calibration file. They are very hard to find as they only available from Toyota directly and cannot be read from the chip."

    Do we have a walk around in order to tweak the shifting a bit?

    Attached is my log and tune file
    Attached Files Attached Files

  2. #42
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    Quote Originally Posted by korbiams View Post
    Thanks @SlowNStock. I managed to amend the shift points, which are honestly not my ultimate goal.

    1-2 shift is remarkably better after making it to shift earlier.

    However 2-3 is still not smooth. The shift is hard and makes the truck to stall. I also noticed that ignition timing goes to Zero at 2-3 & 3-4. Is this normal?

    I have reached HP Tuners support again today requesting for torque management tables. Here is the response:" the shift pressure and trans torque management parameters aren't visible it means that we don't have the slave CPU calibration file. They are very hard to find as they only available from Toyota directly and cannot be read from the chip."

    Do we have a walk around in order to tweak the shifting a bit?

    Attached is my log and tune file
    Yes, timing pulled during a shift is normal, that's torque management doing its job.

    It's a bummer that you can't get to those parameters, that's the easiest way to handle shift quality.



    As a workaround, you can modify the Ignition Efficiency and Ignition Efficiency Inverse tables under "Engine -> Torque Model -> General -> Spark Effects".

    Increasing the efficiency for a given spark in the Ignition Efficiency table will cause the PCM to pull more timing for a given torque reduction request - when the PCM receives a request for torque reduction, it determines a target efficiency and looks up corresponding timing reductions. You need the Inverse table to match accordingly, which requires a bit of math - here's a spreadsheet that will calculate your Inverse table for a given Ignition Efficiency table: Tundra Ignition Efficiency.xlsx

    Simply paste your Ignition Efficiency table on the "Ignition Efficiency" sheet and the Inverse table will be calculated for you - copy and paste that into HPTuners and you're all set.

    You'll really only want to edit the areas affecting your problematic shifts - in this case, MBT ~22 degrees and below.



    The attached is a baseline for you to try, it simply uses the ignition efficiency for higher MBT rows for the lower MBT rows - you may need to try to increase these further if shift quality improves but is still problematic. Your Optimum Trans Input Torque table ("Engine -> Torque Model -> General") is also set back to stock - even the TRD file floating around uses those values, so there shouldn't be an issue using them. ECT max Throttle vs RPM Added (4) _ EDITS.hpt

    Higher values in the torque table causes less spark to be pulled for a given torque reduction - loosely, the ignition efficiency is looked up according to:

    (Current Trans Torque - Torque Reduction) / Current Trans Torque = Target Efficiency

    Artificially high Trans Torque values will cause the Target Efficiency value to be much higher, corresponding to less spark retard.
    Last edited by SlowNStock; 04-04-2020 at 03:44 PM.

  3. #43
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    Quote Originally Posted by SlowNStock View Post
    Yes, timing pulled during a shift is normal, that's torque management doing its job.

    It's a bummer that you can't get to those parameters, that's the easiest way to handle shift quality.



    As a workaround, you can modify the Ignition Efficiency and Ignition Efficiency Inverse tables under "Engine -> Torque Model -> General -> Spark Effects".

    Increasing the efficiency for a given spark in the Ignition Efficiency table will cause the PCM to pull more timing for a given torque reduction request - when the PCM receives a request for torque reduction, it determines a target efficiency and looks up corresponding timing reductions. You need the Inverse table to match accordingly, which requires a bit of math - here's a spreadsheet that will calculate your Inverse table for a given Ignition Efficiency table: Tundra Ignition Efficiency.xlsx

    Simply paste your Ignition Efficiency table on the "Ignition Efficiency" sheet and the Inverse table will be calculated for you - copy and paste that into HPTuners and you're all set.

    You'll really only want to edit the areas affecting your problematic shifts - in this case, MBT ~22 degrees and below.



    The attached is a baseline for you to try, it simply uses the ignition efficiency for higher MBT rows for the lower MBT rows - you may need to try to increase these further if shift quality improves but is still problematic. Your Optimum Trans Input Torque table ("Engine -> Torque Model -> General") is also set back to stock - even the TRD file floating around uses those values, so there shouldn't be an issue using them. ECT max Throttle vs RPM Added (4) _ EDITS.hpt

    Higher values in the torque table causes less spark to be pulled for a given torque reduction - loosely, the ignition efficiency is looked up according to:

    (Current Trans Torque - Torque Reduction) / Current Trans Torque = Target Efficiency

    Artificially high Trans Torque values will cause the Target Efficiency value to be much higher, corresponding to less spark retard.
    Thanks a million man, it surely shifts a lot better.
    1/4 mile improved by 0.3s by only tweaking the Ignition Efficiency table.

    Gonna install Water Methanol injection next week. Then I will try advance timing by 2-3 degrees (currently ~17*, at 5.5 Psi of boost).

  4. #44
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    Quote Originally Posted by korbiams View Post
    Thanks a million man, it surely shifts a lot better.
    1/4 mile improved by 0.3s by only tweaking the Ignition Efficiency table.

    Gonna install Water Methanol injection next week. Then I will try advance timing by 2-3 degrees (currently ~17*, at 5.5 Psi of boost).
    Glad to hear it worked well for you, a good example of how proper torque management can make something quicker. Good luck with the meth install and tuning!

  5. #45
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    Hello Korbiams,

    Currently have a supercharged Tundra (TRD Tune). I do like the TRD Tune, but with lighter race wheels run into a problem on the 2-3 shift bouncing the rev limiter.
    I dont have a problem with the shift itself, but can the rev limiter be raised a bit to avoid hitting the rev limiter. My truck also has meth injection and if you plan to spray 100% Meth pre blower your rotor coating may get eaten.
    Mines did.

    How easy is it to raise the rev limiter with HP Tuners?

  6. #46
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    Figured id post up here. This is on the tacoma side of the fence from tacomaworld.

    "Has anyone dabbled into adjusting Min ECT and Steady Time for knock adaptive learning?

    Everywhere else a normal operating ECT of 176*F and I have seen my truck have a hard time staying above the 182*F mark ( on cold days under light loads for quite some time before fully heated up, so 176*F would seem more proper for that setting.

    As far as the Steady time, anyone know the parameters that it goes against (IE what a steady zone is in relation to adaptive learning?) Knock retard has all of a 1.02 sec steady time vs 3.02 sec of learn up. I figure the quicker we can learn up (say down to 2.5 secs or even 2 sec) could make the truck be able to figure out better timing tables."

    EDIT - also why would we not want to adaptive learn all the way to redline? (5600 rpms in the case of the tacoma)


  7. #47
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    Quote Originally Posted by sctundra View Post
    Hello Korbiams,

    Currently have a supercharged Tundra (TRD Tune). I do like the TRD Tune, but with lighter race wheels run into a problem on the 2-3 shift bouncing the rev limiter.
    I dont have a problem with the shift itself, but can the rev limiter be raised a bit to avoid hitting the rev limiter. My truck also has meth injection and if you plan to spray 100% Meth pre blower your rotor coating may get eaten.
    Mines did.

    How easy is it to raise the rev limiter with HP Tuners?
    Raising the rev limit is very simple, just a single value you can modify, location per this post: https://forum.hptuners.com/showthrea...l=1#post605037

    Quote Originally Posted by nd4spdbh View Post
    Figured id post up here. This is on the tacoma side of the fence from tacomaworld.

    "Has anyone dabbled into adjusting Min ECT and Steady Time for knock adaptive learning?

    Everywhere else a normal operating ECT of 176*F and I have seen my truck have a hard time staying above the 182*F mark ( on cold days under light loads for quite some time before fully heated up, so 176*F would seem more proper for that setting.

    As far as the Steady time, anyone know the parameters that it goes against (IE what a steady zone is in relation to adaptive learning?) Knock retard has all of a 1.02 sec steady time vs 3.02 sec of learn up. I figure the quicker we can learn up (say down to 2.5 secs or even 2 sec) could make the truck be able to figure out better timing tables."

    EDIT - also why would we not want to adaptive learn all the way to redline? (5600 rpms in the case of the tacoma)

    There's no issue, per se, with modifying any of those parameters, but the effects may or may not be as desired.

    KCLV, as implemented, is meant to establish quasi-static corrections for a broad set of factors (e.g., octane), and the learning envelope inherently emphasizes similarly static conditions. We want to learn the optimal KCLV value for each zone, and keep it there; "final" KCLV at operating temp changes relatively little over the duration of a tank of fuel. Broadening the boundaries for learning - lower Min ECT, shorter Steady Time - is conceptually attractive (more opportunities to learn-up), in practice it may be less so: more time spent iterating provides more opportunity for errors to get encompassed in KCLV, resulting in less overall stability in KCLV. If more fidelity were available (additional RPM zones, load axis, etc.), the story could be a little different.

    The arguably better approach is to find typical KCLV values for the fuel you run in each RPM zone, and set your Learn Init near the mean (I like to round down to the nearest 0.5 degree) - that starts KCLV nearly on the money and reaches the "final" value pretty quickly, assuming timing tables are reasonably good.

    To address your specific questions:

    1) Lowering Min ECT to 176 won't be problematic, but it also won't provide dramatically different results, especially if you've adjusted your Learn Init. If additional timing at lower temps is advantageous, encompass that in the ECT Correction spark tables rather than have KCLV adjust for it.

    2) Reducing Steady Time on its face seems like it would make a big difference, but it's not dramatic on the road. I've played with this on Tundras and never found a case where it made a significant impact on how quickly KCLV learned - there are simply very few cases where you are within the envelope for more than 2 seconds, but less than 3 seconds.

    3) Stock shift points are ~5200, so it's only ignoring spark that typically wouldn't be seen in normal driving - may be desirable (not letting an edge case possibly dictate timing), may be undesirable (relying on Knock Feedback). Raising it isn't a problem, just keep an eye on things to make sure there isn't anything causing KCLV in the High RPM zone to artificially learn down.
    Last edited by SlowNStock; 04-23-2020 at 02:32 AM.

  8. #48
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    Can the 2018 tune file be used on a 2008? I am playing with a 2008 sequoia, maybe some of the tables can be copy and pasted if the ecm is different?

  9. #49
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    Quote Originally Posted by SlowNStock View Post
    Raising the rev limit is very simple, just a single value you can modify, location per this post: https://forum.hptuners.com/showthrea...l=1#post605037



    There's no issue, per se, with modifying any of those parameters, but the effects may or may not be as desired.

    KCLV, as implemented, is meant to establish quasi-static corrections for a broad set of factors (e.g., octane), and the learning envelope inherently emphasizes similarly static conditions. We want to learn the optimal KCLV value for each zone, and keep it there; "final" KCLV at operating temp changes relatively little over the duration of a tank of fuel. Broadening the boundaries for learning - lower Min ECT, shorter Steady Time - is conceptually attractive (more opportunities to learn-up), in practice it may be less so: more time spent iterating provides more opportunity for errors to get encompassed in KCLV, resulting in less overall stability in KCLV. If more fidelity were available (additional RPM zones, load axis, etc.), the story could be a little different.

    The arguably better approach is to find typical KCLV values for the fuel you run in each RPM zone, and set your Learn Init near the mean (I like to round down to the nearest 0.5 degree) - that starts KCLV nearly on the money and reaches the "final" value pretty quickly, assuming timing tables are reasonably good.

    To address your specific questions:

    1) Lowering Min ECT to 176 won't be problematic, but it also won't provide dramatically different results, especially if you've adjusted your Learn Init. If additional timing at lower temps is advantageous, encompass that in the ECT Correction spark tables rather than have KCLV adjust for it.

    2) Reducing Steady Time on its face seems like it would make a big difference, but it's not dramatic on the road. I've played with this on Tundras and never found a case where it made a significant impact on how quickly KCLV learned - there are simply very few cases where you are within the envelope for more than 2 seconds, but less than 3 seconds.

    3) Stock shift points are ~5200, so it's only ignoring spark that typically wouldn't be seen in normal driving - may be desirable (not letting an edge case possibly dictate timing), may be undesirable (relying on Knock Feedback). Raising it isn't a problem, just keep an eye on things to make sure there isn't anything causing KCLV in the High RPM zone to artificially learn down.
    Firstly, gotta say between you and JustDSM (who is hella active on the tacomaworld forums, him and I have worked together for tunes, I deal with the 5spd auto found behind the single vvti 1GR on the tacoma) Your information and the way you explain it is AWESOME.

    Everything you have stated makes sense.


    My next question to you is, Ideally do you want to fine tune base timing maps to have a similar average KCLV across each zone?

  10. #50
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    Quote Originally Posted by rockchip View Post
    Can the 2018 tune file be used on a 2008? I am playing with a 2008 sequoia, maybe some of the tables can be copy and pasted if the ecm is different?
    Most of the tables are the same - copy the changes you'd like over into the 2008 file and flash that.

    Quote Originally Posted by nd4spdbh View Post
    Firstly, gotta say between you and JustDSM (who is hella active on the tacomaworld forums, him and I have worked together for tunes, I deal with the 5spd auto found behind the single vvti 1GR on the tacoma) Your information and the way you explain it is AWESOME.

    Everything you have stated makes sense.


    My next question to you is, Ideally do you want to fine tune base timing maps to have a similar average KCLV across each zone?
    Glad to hear my posts have been helpful; I benefited immensely from others sharing knowledge and information when I was learning, and want to pay it forward as much as I can.

    In general, yes, we want to keep a pretty similar KCLV across zones; usually we'll wind up with a bit less in the High RPM zone, that's somewhat expected - as long as the zones are within 1 degree of one another, it's close enough to call "done", not much benefit to trying to sharpen the pencil more than that.

    The trickier problem is within an RPM zone - we can run into situations where the KCLV for low load and high load within the same RPM zone wind up being quite a bit apart. This is most noticeable in the Low RPM zone, simply because during typical driving the loads encountered in that zone will cover most of the spectrum from low to high (compare that to the High RPM zone, where we encounter almost exclusively high loads). Here's my preferred approach:

    (A) If KCLV is higher at high loads, retard cam timing and/or increase overlap (EGR) at low loads
    (B) If KCLV is higher at low loads, add timing (up to MBT) at low loads

    Here's the unfortunate caveat to this method: (A) works well with Dual VVT (Tundra) because you can change overlap (internal EGR) and dynamic compression ratio (DCR) independently. With single VVT, (A) is a lot less useful as increasing EGR (advancing intake) also increases DCR, and decreasing DCR (retarding intake) decreases EGR - increasing timing at high load (again, only up to MBT) is often the route to go.

    Just like between zones, aim to keep KCLV varying ~1 degree from low to high load for a given RPM column.

    I have some transmission tuning stuff (shift scheduling) I might share via PM, need to make a few more changes before it's ready.

  11. #51
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    Thanks for all the info Slownstock! I need to study up and get tuning😁

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    Quote Originally Posted by SlowNStock View Post
    Most of the tables are the same - copy the changes you'd like over into the 2008 file and flash that.



    Glad to hear my posts have been helpful; I benefited immensely from others sharing knowledge and information when I was learning, and want to pay it forward as much as I can.

    In general, yes, we want to keep a pretty similar KCLV across zones; usually we'll wind up with a bit less in the High RPM zone, that's somewhat expected - as long as the zones are within 1 degree of one another, it's close enough to call "done", not much benefit to trying to sharpen the pencil more than that.

    The trickier problem is within an RPM zone - we can run into situations where the KCLV for low load and high load within the same RPM zone wind up being quite a bit apart. This is most noticeable in the Low RPM zone, simply because during typical driving the loads encountered in that zone will cover most of the spectrum from low to high (compare that to the High RPM zone, where we encounter almost exclusively high loads). Here's my preferred approach:

    (A) If KCLV is higher at high loads, retard cam timing and/or increase overlap (EGR) at low loads
    (B) If KCLV is higher at low loads, add timing (up to MBT) at low loads

    Here's the unfortunate caveat to this method: (A) works well with Dual VVT (Tundra) because you can change overlap (internal EGR) and dynamic compression ratio (DCR) independently. With single VVT, (A) is a lot less useful as increasing EGR (advancing intake) also increases DCR, and decreasing DCR (retarding intake) decreases EGR - increasing timing at high load (again, only up to MBT) is often the route to go.

    Just like between zones, aim to keep KCLV varying ~1 degree from low to high load for a given RPM column.

    I have some transmission tuning stuff (shift scheduling) I might share via PM, need to make a few more changes before it's ready.

    Again, thanks for the well explained info. Super informative. As far as i know in the Tacoma tunes we dont have an MBT table like i have seen in the tundras. That stated, looks like my awesome tune up from JustDSM is doing pretty darn good. Keep in mind this log is only on its 4th short drive after flashing a new trans tune (my final revision of a new public "v13" trans tune to be released likely later today) so there hasnt been much drive time in the mid / upper zones

    kcl.pngkfb.pngcounts.png

  13. #53
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    Quote Originally Posted by rockchip View Post
    Thanks for all the info Slownstock! I need to study up and get tuning��
    Keep the questions and conversation going - the more info we have out there, the easier it is for everyone, the easier it is for everyone, the more quality and quantity of support improves. The Toyota tuning world is still pretty niche, would be great to see it grow.

    Quote Originally Posted by nd4spdbh View Post
    Again, thanks for the well explained info. Super informative. As far as i know in the Tacoma tunes we dont have an MBT table like i have seen in the tundras. That stated, looks like my awesome tune up from JustDSM is doing pretty darn good. Keep in mind this log is only on its 4th short drive after flashing a new trans tune (my final revision of a new public "v13" trans tune to be released likely later today) so there hasnt been much drive time in the mid / upper zones

    kcl.pngkfb.pngcounts.png
    Yup, no MBT table on Tacoma, unfortunately, so it's a bit more difficult to know how much is too much - referencing it is more of a caveat emptor. Even with the MBT table on Tundras, some liberties have to be taken because it's not 1:1 with the timing tables.

    Your log looks pretty good, right what I'd expect from some short drives and given cell counts; those cells around 60% load and 2000-2400 RPM should fall in line on a longer drive.

    You may try filtering for throttle transients when looking at KFB and KCLV (if you aren't already), won't make a huge difference in well populated regions, just cleans up some outliers - a reasonable baseline would be a delta of <1% over 1s (1000ms): abs([THROTTLE_PID.155.slope(1000)]) < 1, where THROTTLE_PID is whichever channel you're logging (.155 formats the output as a percentage).

  14. #54
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    Quote Originally Posted by SlowNStock View Post
    Keep the questions and conversation going - the more info we have out there, the easier it is for everyone, the easier it is for everyone, the more quality and quantity of support improves. The Toyota tuning world is still pretty niche, would be great to see it grow.
    Hey SlowNStock, I'm having an annoying RPM drop on decel. According to someone on the Tundra forums it's normal and they of course suggested a tune so I'm hoping there's an easy, known fix before I start guessing at it. If you look at this log from 16:52.30 to 16:53.30 you'll see several instances where this happens, RPM drop accompanied by huge drop in timing and a little bump in load. Sometimes it coincides with DFCO activity, TCC locking/unlocking and the fuel system saying open loop not ready in between periods of open loop accel/decel but none of those are present every time these events happen. I don't want to start blindly messing with things and inadvertently cause problems elsewhere since the truck is running smooth and strong with great throttle feel everywhere else. Just a stock 2014 Tundra with exhaust, non flex fuel. I haven't messed with the idle spark or low load area of the VVT tables yet. Thanks for all the info you've been sharing!


    4-12-20 log post vvt edit.hpl
    Last edited by Fullpower; 04-28-2020 at 12:19 AM.

  15. #55
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    Quote Originally Posted by Fullpower View Post
    Hey SlowNStock, I'm having an annoying RPM drop on decel. According to someone on the Tundra forums it's normal and they of course suggested a tune so I'm hoping there's an easy, known fix before I start guessing at it. If you look at this log from 16:52.30 to 16:53.30 you'll see several instances where this happens, RPM drop accompanied by huge drop in timing and a little bump in load. Sometimes it coincides with DFCO activity, TCC locking/unlocking and the fuel system saying open loop not ready in between periods of open loop accel/decel but none of those are present every time these events happen. I don't want to start blindly messing with things and inadvertently cause problems elsewhere since the truck is running smooth and strong with great throttle feel everywhere else. Just a stock 2014 Tundra with exhaust, non flex fuel. I haven't messed with the idle spark or low load area of the VVT tables yet. Thanks for all the info you've been sharing!


    4-12-20 log post vvt edit.hpl
    Have you made any other changes in your tune? If so, please post up a copy.

    The posted log has a few too many channels to get precise data (I realize that's probably my fault for not giving usage guidelines in my earlier post). Here's a set of channels to use for logging that should give a little better picture of what's going on: Tundra_RPM_Drop_Channels.Channels.xml. Fewer channels and some priorities given to polling intervals decreases the net polling interval. I have a fix in mind, but would like to confirm some other things with a log using the attached channels first.

  16. #56
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    Quote Originally Posted by SlowNStock View Post
    Have you made any other changes in your tune? If so, please post up a copy.

    The posted log has a few too many channels to get precise data (I realize that's probably my fault for not giving usage guidelines in my earlier post). Here's a set of channels to use for logging that should give a little better picture of what's going on: Tundra_RPM_Drop_Channels.Channels.xml. Fewer channels and some priorities given to polling intervals decreases the net polling interval. I have a fix in mind, but would like to confirm some other things with a log using the attached channels first.
    Thank you, I've adjusted a lot of things a little bit at this point so I'm going back to a basically stock tune for a bit to see if the problem still occurs or if I had inadvertently caused it. I'll log with those channels if it's still happening and if it's fixed then I will slowly work back to where I was before and hopefully figure out what exactly caused it. I'll post up here if/when I learn something or if it reoccurs on the stock tune file.

  17. #57
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    Quote Originally Posted by SlowNStock View Post
    Have you made any other changes in your tune? If so, please post up a copy.

    The posted log has a few too many channels to get precise data (I realize that's probably my fault for not giving usage guidelines in my earlier post). Here's a set of channels to use for logging that should give a little better picture of what's going on: Tundra_RPM_Drop_Channels.Channels.xml. Fewer channels and some priorities given to polling intervals decreases the net polling interval. I have a fix in mind, but would like to confirm some other things with a log using the attached channels first.
    OK here we go, running my stock tune file but with a slightly more aggressive throttle curve and AIP fault delete. My commute to work is the first log and it happens a lot while heading down a few hills after leaving my house notable from around 9:10.42 to 9:12. 2nd log I added spark advance and throttle channels for the drive home which doesn't have many instances of zero throttle coasting but there were two good instances of the RPM drop, first and most annoying example is at time stamp 18:02.33, another is at lower speed 18:12.15. I see what's going on but it's not clear to me what parameter(s) may help smooth that out as Toyota seems to use a lot of tables that interact in non-intuitive ways (to me at least).
    Attached Files Attached Files

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    Quote Originally Posted by Fullpower View Post
    OK here we go, running my stock tune file but with a slightly more aggressive throttle curve and AIP fault delete. My commute to work is the first log and it happens a lot while heading down a few hills after leaving my house notable from around 9:10.42 to 9:12. 2nd log I added spark advance and throttle channels for the drive home which doesn't have many instances of zero throttle coasting but there were two good instances of the RPM drop, first and most annoying example is at time stamp 18:02.33, another is at lower speed 18:12.15. I see what's going on but it's not clear to me what parameter(s) may help smooth that out as Toyota seems to use a lot of tables that interact in non-intuitive ways (to me at least).
    So after some study I think I finally figured out the cause and worked out what is so far an acceptable solution for me. I think what I was experiencing was torque management in anticipation of a downshift (hence the severe spark advance drop) while coasting/slowly decelerating and due to the hilly terrain where I live the truck would accelerate slightly and then not complete the shift. I noticed a very similar spark drop during completed shifts, TCC activity and coming out of DFCO so it makes sense to me that torque management from an aborted shift would cause the same spark drop as well as a momentary engine load increase and RPM drop. Regardless, the fix I'm testing currently is simply raising the Minimum Final Spark from -10 degrees to 0. About 30 miles since the edit and so far so good plus a nice side benefit of crisper shifts since I essentially reduced the torque management as well, it's not at all harsh and I haven't had any new issues crop up from the change at this point. Adjusting shift points would have been my next step since I haven't changed anything there yet but this was much quicker and easier test.
    Last edited by Fullpower; 05-01-2020 at 09:38 PM.

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    Quote Originally Posted by Fullpower View Post
    So after some study I think I finally figured out the cause and worked out what is so far an acceptable solution for me. I think what I was experiencing was torque management in anticipation of a downshift (hence the severe spark advance drop) while coasting/slowly decelerating and due to the hilly terrain where I live the truck would accelerate slightly and then not complete the shift. I noticed a very similar spark drop during completed shifts, TCC activity and coming out of DFCO so it makes sense to me that torque management from an aborted shift would cause the same spark drop as well as a momentary engine load increase and RPM drop. Regardless, the fix I'm testing currently is simply raising the Minimum Final Spark from -10 degrees to 0. About 30 miles since the edit and so far so good plus a nice side benefit of crisper shifts since I essentially reduced the torque management as well, it's not at all harsh and I haven't had any new issues crop up from the change at this point. Adjusting shift points would have been my next step since I haven't changed anything there yet but this was much quicker and easier test.
    Sorry for the delay, been caught up in some personal projects

    My suggestion was going to be to increase the spark minimum ("Engine -> Spark -> Minimum Spark -> Base") up to 40% Load and 1600 RPM to 0 degrees and bump up the downshifts to 1100 RPM if it persisted, so you clearly already had the same line of thought.

    There's nothing in the tune you uploaded that should be causing the issue; I tried, but wasn't able to recreate on my Tundra. Only time I've seen something similar was an intermittent IAT or ECT sensor, your logs don't show that being the problem.

  20. #60
    Tuner in Training
    Join Date
    Oct 2013
    Posts
    18
    Quote Originally Posted by SlowNStock View Post
    Sorry for the delay, been caught up in some personal projects

    My suggestion was going to be to increase the spark minimum ("Engine -> Spark -> Minimum Spark -> Base") up to 40% Load and 1600 RPM to 0 degrees and bump up the downshifts to 1100 RPM if it persisted, so you clearly already had the same line of thought.

    There's nothing in the tune you uploaded that should be causing the issue; I tried, but wasn't able to recreate on my Tundra. Only time I've seen something similar was an intermittent IAT or ECT sensor, your logs don't show that being the problem.
    No worries man, this was really only happening under some pretty particular circumstances that unfortunately were consistently showing up during a couple parts of my daily commute...most of the time during normal driving I wouldn't have any issues. We'll see, hopefully I'm on the right track and it stays away so I can get back to the fun stuff