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Logging Clutch Shift Type should be reliable, assuming we've mapped it correctly. It pulls from the internal value that is used to decide which set of tables the TCM actually looks at.
So as you mentioned, its releasing a clutch and applying a clutch.
This is true of every shift the transmission does.
Every gear change the ZF8 commands is one of these "clutch" to "clutch" shifts. The ZF8 has 5 of these, and has 3 active at a given time for the gears 1-8 and reverse. Park/Neutral has 2 active, so shifting from Neutral to Reverse/Drive has a single engagement.
So it releases one clutch and applies another to shift.
The releasing clutch is called the offgoing clutch, and the engaging one the oncoming clutch.
Depending on whether its an upshift or downshift, under power or coasting, the actual "stages" of shift are different, but those are mostly unimportant, and in the case of "under power" or "coasting" is mapped in tables as positive or negative torque.
First, understand that a clutch pack can hold a certain amount of torque depending on how much pressure its held together with. This pressure is transmitted by various means, but its usually a small chamber (a clutch chamber/volume) that has a piston that pushes the clutch packs together, and a spring that returns it back to open (so that with no pressure the chamber empties). By default, when you're driving down the road, the pressure doing this is the "line pressure". Higher pressure has higher torque capacity, but if you look at the line pressure table, you'll see they modify it as torque moves. Higher pressure requires the oil pump in the transmission to work harder, and causes more drag, so its controlled to have enough torque capacity but not excessively so, in order to keep efficiency high.
Now when a shift happens, we want to remove the torque capacity from one clutch, and transfer it to another. To reduce drag and improve efficiency again, we typically have clutches sitting empty to help minimize any movement they have when not active. So we have to fill our oncoming clutch, and empty our offgoing clutch, but do so in an organized manner so that we don't break anything inside the transmission and hold as much torque as we can during the shift, and go as quickly as we can.
So I'll divide the shift into a few sections:
Fill->Torque Transfer->Inertial Phase->Maintenance
Fill
During the fill phase, we fill the oncoming clutch with oil again, up until the point it starts actually building pressure in the chamber. Essentially the clutch solenoid valve targets a set "pressure" (really its just an opening of the valve, look at the characteristic curves for the solenoid)
There are actually three sub-phases: A prefill, where the ATF is pumped into the chamber just until it starts to hit resistance from the piston/spring, a fast fill to move the piston to move it so the clutches are just nearly touching, and a stable fill (we call just fill) that moves the clutch packs until they just "kiss" and have 0 torque capacity.
Tuning this stage is complex, and if you want to learn more, I'd suggest this paper: Dynamic Analysis and Control of the Clutch Filling Process in Clutch-to-Clutch Transmissions
There's a lot of math in here, but the ideas are also expressed in somewhat plain English if you'd like to learn more.
The time this takes we want to be as quick as possible, as its responsible for a big amount of delay we feel in a shift.
Torque Transfer
During this stage, we transfer the torque capacity from the offgoing clutch to the oncoming clutch. We do this using a targeted oncoming rate and pressure, and a targeted offgoing rate and pressure. Now, when calibrating we put in the oncoming target pressure and offgoing target pressure, as well as ramps.
These are however only guidelines, the transmission internally is trying to hit a targeted slip while doing this transfer (for the ZF8 I have not identified what this is or how its controlled, but I know it happens). So the transmission itself attempts to adapt these pressures while shifting to hit these goals.
At the finish of this stage, our oncoming clutch is now holding all the internal torque of the transmission, and the offgoing is holding none.
Really the only tuning parameter we have for this step is the Oncoming and Offgoing rates. And we only have the offgoing control during downshifts, during an upshift, we don't have control on the ZF, as its internally managing this to manage the RPM drop and internal slip.
I should mention, the oncoming clutch is still "slipping" at the end of this stage, but its now transferring full torque. This slipping is required as the output of the clutch isn't necessarily at the same speed as the input. Reducing this slip to zero is the goal of our NEXT phase.
Inertial/Slip Phase
This is the stage we normally think of as the "shift". Its when the engine speed starts to change (and in fact the speeds of all the stuff inside the transmission as well!) and we start to feel like we're shifting. During this phase, we're basically waiting for the oncoming clutches slip to reduce to zero. We do this by controlling its pressure.
Now that torque has been transferred internally, everything has to "catch up". These internal torques now act on new planetary gear sets, the input shaft, and turbine. During this step is when RPM actually drops or rises as the turbine drags the engine down or up. If you were wondering why our oncoming pressure is adjustable by gear, its because these internal torques change per gear.
So, we have a target slip time. This is how long we expect this ratio change to take up. If we want to speed up our perceived shift, we target a shorter time here. We likewise will need MORE oncoming pressure to deal with these higher internal torques. Likewise, this is where torque management comes into play in a very important regard. During an upshift, any torque the engine is producing has to be handled by the transmission in addition to what its already handling as internal components are speeding up or slowing down. By having increased engine torque, we have increased pressure desired, and we have increased the amount of energy that the oncoming clutch bears. To make this job easier, we have upshift torque management, to reduce the strain on the transmission, and in this case it will actually SPEED UP the process of the shift as we'll have less slip and energy to control. So we can actually complete our shift faster with the correct amount of torque management. Too little and we're harming things and slowing it down, too much and we're slowing the car down when it comes out of the shift unnecessarily.
On a downshift, we reverse this process a little, we actually want torque from the engine to help us speed up the shift (raise the engine RPM and rev match!). Too little and we're again just wasting time, and too much and we're overreving and causing excess wear as the clutch has to bring it back down.
But typically, faster slip times and more engine torque mean we need more clutch torque capacity, and so you see as we target more torque or faster shifts, our pressures increase.
As well, the offgoing clutch really shouldn't be apart of this phase. Once the oncoming clutch is handling torque, if the offgoing one was as well, we'd start to have parts of the transmission fight each other. This is called "tie-up" and slows our shift down (and puts a lot of strain on the gears and clutches!). Hopefully we picked good values while ramping it off previously!
Now if we don't apply enough oncoming pressure to handle everything, we might actually have the engine kind of overshoot its target RPM on shifts. We call this "flare" on a downshift (the engine overspeeds the target input speed before its brought down) and "slip" on an upshift (it feels like the engine kind of slowwwwly slides into gear). So, our goal here is to set pressures knowing our targeted shift time. Ultimately, we're limited by how much pressure we can generate, and the torque capacity of our clutches. The faster we want this phase to happen, the more internal torque we need to do so, and the higher the pressure and more slip we potentially face. OEMs balance this with comfort in mind as well. If this phase isn't smooth, the user feels it. A fast shift that's a little sloppy might have a burst of torque or a drop in it on the output shaft, and you feel this (the shift "chirps the tires" or "bogs down").
Most of your time tuning a transmission, your goal is to speed up shifts or change the quality of them, so you play a careful balancing act between shortening the slip time and increasing the pressure.
As well, internally there is adaption happening where the transmission is trying to adjust the oncoming pressure to hit the target slip time. If it has to adjust too far, you actually will get DTCs indicating clutch failures (and it'll even know which clutches are possibly failing because of the shifts it notices the problem on!
My best advice for tuning this is shortening the shift or reducing the torque management means more pressure is needed to handle the higher internal torques. If you allow flare or bogging to happen, all that energy is being dumped into the clutches wearing them out prematurely. There is an eventual limit where you simply can't go any faster before it happens that you will hit, and that's a limitation of the clutch materials and pressures you can apply. A beefier trans that can better handle those stresses is necessary, but then you may also have to retune all the low power shifts so they still feel soft and gentle :) Keep in mind raising the target pressure also extends the torque transfer phase, as you need more time to get the pressure and torque capacity to that level!
Maintenance
This phase is boring. Oncoming pressure is set to line pressure to make sure the clutch doesn't slip. During this step, its just making sure the oncoming clutch pressure allows zero slip. The offgoing clutch has no pressure applied, and is slowly draining away (there's an empty time that is mapped to indicate how long this takes).
Tuning this means tuning the line pressure tables.
I know thats a lot to digest, and if you want to learn more, I suggest taking a read of Virtual Clutch Controller for Clutch-to-Clutch Shifts in Planetary-Type Automatic Transmission.
While reverse engineering the ZF8, I found this to be very helpful in trying to figure out how they were managing the shifts and plotting them out.
Also as a quick aside to what "phase" you should target while tuning:
If you want the "delay" from when a shift is commanded to when you feel it "start", you need to tune the fill and torque transfer (ramp) phases. You don't feel anything happen until this completes and inertial transfer starts! An aside here, a lot of people perceive lots of transmissions to have long delays from the triggering a paddle to the "shift" happening. Most of the time, its not a hardcoded delay, but is actually these two phases executing. Part of what makes the ZF8 a great transmission is that it can accomplish both these phases very quickly, making it feel like when you press the paddle, it shifts right away!
If you want the "delay" as the ratio is changing to be different, you need to tune the inertial/slip phase. Keep in mind, the faster you want to do this, the more torque you see internally, the more energy the clutch sees, and the faster it can wear! This is balanced by OEMs to be comfortable and provide good service life. We may have different goals in mind in the aftermarket (or in fact beefed up the clutch packs so they can handle more energy!).
Hopefully that's as thorough as you need, or more than that. If you want to learn more, check out the links I provided.
Good luck!
That's a lot of information, but as i read it a few more times i believe this is very beneficial in learning how the ZF8 transmission works. I haven't got to the tuning side of the trans yet but this explains a lot of what we need to be looking at when it comes to applying changes to the trans to get the shift preferences we want and to also keep the trans from just eating itself in a short time.. Thanks You for this information i will be bookmarking this!! Keep this type of stuff coming i love learning the why rather than just being told to change this and that.
We may need to update some axis descriptions. Turbine torque isn't the reference for those, I will have them updated.
"Turbine Torque" as seen by the ZF is more like the torque going through the converter's fluid section. It will reduce when locked as now the turbine is ideally locked (though only truly 1 to 1 locked when in Overlock) to the impeller and there's no torque difference across the converter.
My recommended one to log is 4403 - Trans Engine Torque. This If it's not available on yours, send a ticket in. It's available on the ZF8HP2 TCM for sure as I mapped it for that.
Thanks for the detailed post. I've done a lot of experimenting with making 8HP70 survive bring raced a lot at high torque in a heavy car and your explorations go right along with what I've found. It really is a balancing act to get everything right but makes such a big difference and keeps the transmission healthy.
Thanks for all the hard work Steven.
This is great information and was timely for me as I've been digging in to the trans calibration the past week to better understand it on my 2016 Hellcat A8.
It seems when I log transmission PIDs my VCM Scanner gets sluggish and it jumps a lot in displaying the data. Anyone else see that issue? I can literally have only 10 or 12 pids logged for engine and it's all good, I add "ShiftID" and everything gets sluggish like the RPMs aren't logged smoothly, etc.
I also reviewed the other thread about driver type mapping to aggression tables and had a question. Is there a reason you couldn't just change the driver type table to be all aggressive to force it to use the aggressive tables and limit the number of tables you have to go modify?
So in these tables just fill the driver counter to all "600" or even "100" to make it happen sooner and the upper and lower driver type and aggression "14" and "3" respectively?
Attachment 94996
Thanks, I didn't realize you could prioritize PIDs, I'll see if I can figure that out!
Ok, seems the pid poling times were already set to 0ms for quickly changing items and slower for others so that's not the issue for me it seems. I can try lowering the slower ones further but some are 200ms, 500ms + already.
One of the biggest issues I have with these transmissions (specifically the 8HP70) is hitting torque limits after doing heavy engine modifications. I can get around it by disabling a lot of torque management but I don't like doing that. On these if we change the torque limits (Trans---General--->Max Torque Limit and Trans----General-----Gear Based ----Normal) it causes the trans to go into limp mode with 2 codes, P1DD2 and U0402. More specifically this seems to really only be an issue when adjusting the Gear Based----Normal setting. This would very much help to allow us to push up the power levels without completley disabling torque management
You maybe need a different approach.......rather than broadcasting to the world (and the trans) all your newfound power, consider a more stealth method.
Get the PCM to under-estimate the tq you are making. Remember these are just numbers...no correlation to real tq.
It will take some rescaling of airflows etc but you can feed it whatever numbers needed to keep you under limits.
As the PCM is under reporting tq, you will now have to rescale pressures in TCM(as it will see lower tq numbers than actual) but it will remain cool and unflustered.
You can the crank up pressures/shift times till your neck hurts or it breaks the trans (obviously not desirable) but not hit any limits.
The tq management can be kept in and tuned to suit the new numbers also.
Obviously it is a bit of work and PCM/TCM must be tuned together, but if you have the patience the results can be amazing.
They are a gooood trans.
I actually took an approach basically identical to what you just described on a test mule last weekend. I had been thinking about it and remembered we had the ability to control the estimated tq values. I figured if I could get the PCM to think the tq value was lower the TCM wouldn't step in and reduce tq. Once I figured that side out on the dyno, then I worked on the tcm shifting pressures as well as how much tq reduction was used for shifts. When finished it drove like stock under normal conditions, and then when hard in the throttle shifting became very firm and quick. I had some others drive it as well and they loved it so I'm going to implement it into one I'm working on now to see how if I can replicate the results on a different setup. Thanks for the advice, good to hear someone else came up with the same approach and has had success with it as well.
Steven, did you ever get around to this? I'm too searching for the right parameters to log shift pressures, time, gear, etc and am not seeing available PIDs. Also shouldn't we have actual/expected engine torque? I dont have those either. Thanks!
I have been having similar issue with the 8hp70 transmission on a 3.0 eco. With additional power to the engine the trans seem to go in and out of limp mode constantly. I had similar issue with torque management and causing cel when tcm torque management limit was set higher in the TCM then the PCM. If I'm reading this thread correct it sounds like turning the pcm down a bit more might stop the constant limp mode active/not active scenario I'm seeing on just the tcm. It doesn't throw a cel on the dash only see it in the WiTech software when graphing the pid for limp mode on the TCM.
ive copied your write up on the ZF8 as it is great info. i have a 5 speed nag1, would this info be the same for the nag1?
Anybody have any info on the Oncoming Ramp numbers? Trans -> Shift Pressures -> Upshift/Downshift -> Oncoming Ramp
From what I've seen so far the higher the number in the oncoming ramp table means a slower apply rate. Keeping these numbers around 50% of the actual pressure in the oncoming clutch tables seems to keep it around "stock" feel even when I double the pressure. I also haven't proven it out but I feel like the slip times factor into this but more from a torque management perspective.
Here are things I've found so far:
- Just doing a straight 20% increase of Oncoming pressure firms up shifts but still leaves a small delay before the shifts in some spots - feels like engine spark/power reduction over transmission delay.
- Double oncoming pressure and match the oncoming ramp to 50-60% of the oncoming pressure at same torque values keeps the shifts firm but removes some of the delay.
- The closer to zero on the oncoming ramp tables seems to INCREASE shift firmness / speed.
- Increasing the oncoming ramp rate on the 2-1 downshift for all the zero/negative torque values smoothed out the downshift so it doesn't "bump" as much when near idle.
- Decreasing the oncoming ramp rate on the 2-1 downshift for all the zero/negative torque values firmed up the downshift so it "bumps" more near idle.
I'm slow at figuring this out due to time and the lack of logging features for this transmission (or lack of finding them). I'm used to the 6L80 that had shift times that could be logged.
Attachment 116258
I haven't messed with the ramp on mine, only the clutch pressure.
The base line pressure for each gear under general? What results are you seeing there?
I bypassed that because on the 6L80 that was more of just what is available and didn't do anything unless the line pressure was lower than the requested pressure for the clutches.
Sorry, was doing it from memory and I used the wrong term (I corrected my post).
I've not adjusted any of the ramp settings, only the on coming clutch pressures on the Upshift tab and I only increased the last 2 or 3 rows. This basically firms up shifts at WOT.
Okay cool, how much higher have you gone? I've gone double stock so far and it seems to not care much - this is with messing with the ramps also though. I think I'm going to revert everything to stock, increase all the oncoming pressures by 25% and decrease the ramps by 25% and see how that works out.
You can use a Demon calibration as a guide. Just be careful with the trans stuff, you can hurt them pretty easy if you get the settings wrong.
I looked at a 2018 demon file I found on the forums and now I just have more wants. Demon seems to have lower pressures compared to the RAM which makes sense. I've tuned the 6L80 wrong before, I for sure know what wrong feels like; I've applied so much pressure before I thought I was going to snap the driveshaft in half, lol. This ZF seems like its on par or better than the 6L80 when it comes to strength even though its too soon to tell.
I've circled all the values missing on my files. Not sure if this just isn't mapped yet for the RAM or it isn't available on the 2019+. I guess if I don't hear anything from HP tuners here soon I'll submit another support ticket.
Attachment 116298
I have taken this approach when remapping the 850RE on the Gladiator. The issue I currently have is if I drop the airflow anymore in order to engage 8th gear at cruise, 70-85, I cannot set the torque in the pedal demand tables to something that will generate enough power to hold cruise in 8th and 9th reliably.
I would really appreciate the ability to bump up the entrance torque by gear an not set of the torque request to high DTC. The max limit on the Gladiator seems to be 406. When I set 8th gear normal to 506 the transmission slides right into 8th like factory, but ahortly after the fault trips and I am stuck in 8th until I key cycle.
The ability to manage the max torque by gear and eliminate that fault got ng off would pretty much complete my tune for the supercharged Gladiator.
I've had a chance to experiment with stuff more. Take this with a grain of salt as this could be completely incorrect and only based on my experience and tuning so far.
Shift Pressures -> Upshift -> Oncoming Ramp
Shift Timing -> Upshift -> Ramp Time
These two seem to correlate to each other. I'm going to call this the Oncoming Clutch apply rate. I've zeroed out these two tables and its actually the "proper" way I'd go about it for tuning the correct pressure since this seems to mask any issues with correct pressures and timing. If everything is zeroed out you can think of the oncoming clutch pressure as "on" and 0 torque (clutch plates just touching) as off, it is instant and as fast as possible. The ramp smooths out how fast this happens. 50ms and a ramp of 0.5 is a good starting point for initial tuning.
I don't completely understand the math behind these two parameters but it seems to be inverted from what you'd normally think. The lower the ramp rate (bar/s) the less it dampens.
EDIT: 1.0 ramp near the upper torque rows is probably better to start on.
Shift Pressures -> Upshift -> Oncoming Clutch
This is the actual pressure that gets applied to the clutches and is what you feel as the final portion of the shift or the RPM differences from what I can tell. If the ramp is too aggressive it makes this stage really hard to tune. 6 bars is about the max you want to use here. I've gone to 9 bars and at the point where it feels like your going to break internals or driveshafts. 0.6-1.0 bar seems like a decent place to be on lower torque areas and 5-6 is a good spot for firm shifts in the higher torque areas. 2.5-4 seems to be the sweet spot for "smooth" shifts.
Shift Pressures -> Upshift -> Offgoing Clutch
This is just how much pressure is used to hold the current clutch while phasing in the next clutch. When going for aggressive tuning, I always zero this out. My theory is if the shift is fast and firm enough you don't need to hold this and its too hard to tell if you are doing premature wear until its too late.
Shift Pressures -> Upshift -> Fill Offset
I don't have as much experience with these tables but this seems to pre 0 torque condition of both plates slipping. Not enough pressure here and you'll see a flare and too much and you'll have an overlap condition. The ZF8HP75 on the 2019 RAM for example I couldn't figure out for the life of me why the 3-4 shift was "binding" until I lowered these. My advice is if you increase oncoming clutch pressure by say 20% you should lower the fill offset by at least 10%.
EDIT: After more tuning, increasing the oncoming pressure, less ramp, and possibly holding the offgoing clutch longer is a lot easier. The values in the fill offset are extremely sensitive. Changing by 0.01 bar was enough to make it flare 100-200RPM during the shift. 3-4 on my vehicle (2019 RAM) the fill offset on the low end were too low by ~10% and the upper I couldn't change from stock without flare so I increased the ramp (pressure not time) to avoid binding.
EDIT2: After more tuning I realized I was getting owned by adapts. It seems the current settings here are only good until a key cycle. The second ignition cycle the adapts adjust everything and will mess up tuning in this section. The stock tune for example on the 3-4 has a lot of values that are way too low on the low end torque and low RPM. (0.10 bar @ 74 lb-ft / 1702RPM). After driving on the first engine start and having flares, the second start would see the majority of the flare go away, third even more. The farther away from "correct" the more key cycles it takes. The same value I mentioned before took almost x3 more pressure to not flare after an adapt reset. I suspect without an adapt reset any added pressure is too much as the adapts have already adjusted for it and its too dumb to know we modified the tables.
Edit3: This seems more like a preliminary stage of the oncoming clutch pressure. If the fill offset is 1.0 bars and the oncoming shift pressure is set to 2.0 bars and there is a ramp the actual pressure applied seems to be 1.0 to 2.0 bars. the fill offset is the "floor" or base of when the pressure gets applied. I don't believe this should be above the oncoming shift pressure. Consider it fine tuning for the ramp and a way to move the shifts closer together.
Shift Pressures -> Upshift -> Flare Adder
I haven't actually played with this one yet but it seems pretty self explanatory. If the Fill offset isn't high enough these tables say how much pressure needs to be added to make up for the slip.
Shift Timing -> Upshift -> Nominal Slip Time
As far as I can tell this doesn't have any say on how fast the shift actually takes place. This held true for my tuning of the 6L80 (GM) also and I'm going to assume it applies here also. This is more or less the time it takes for the Torque Reduction stage to happen, the shorter this time the faster and less time the engine pulls back torque (timing). If you have a flat spot or hang in the middle of the shift, more than likely this is too long.
Torque Management -> Upshift -> Forced Torque Intervention
I didn't play in this area too much but this seems to be the pre-cursor torque management stage. I played around with this by making it so the all the values would equal 0 engine torque (5500 turbine speed @ 350 ft-lb = -350) would actually cause the transmission to never shift even at WOT because it guaranteed the output shaft speed never hit the right speed to shift. It went into a really fun bounce back and forth of the RPMs but never shifted. If I added power to the engine I would account for it here to protect the transmission.
Torque Management -> Upshift -> Main Torque Intervention
This is basically the same as forced torque intervention but is applied DURING the shift instead. Again if I added power to the engine I would account for it here to protect the transmission. From what I can tell on the RAM 200 ft-lb is roughly what OEM spec'd at as reliable; This is a huge increase from the 6L80 as it usually never seen over 40-70 ft-lb on a shift.
EDIT: WOT drops the torque a little bit lower. Roughly around 130 ft-lb which is what I'd expect.
NEW 5/19/22:
Shift Timing -> Oncoming Inertia Mode Delay
I haven't quite figured this one out but reducing this and keeping this LONGER than the offgoing inertia mode delay seems to help the shift timing. I believe this is when the clutch start to engage.
Shift Timing -> Offgoing Inertia Mode Delay
I haven't quite figured this one out but reducing this and keeping this SHORTER than the ongoing inertia mode delay seems to help the shift timing. I believe this is when the clutch start to disengage.
Shift Timing -> Fill Time
I've had really strange delays in WOT shifts and randomly in other spots (very obvious in WOT shifts). Reducing this when increasing the shift pressure seems to have helped here. I suspect too long of a fill time causes the transmission to attempt to reduce or "bleed" the pressure before the shift actually happens causing a really long delay that can be felt. 100ms seems okay here across all temperatures so far. I haven't tested in cold weather yet, this will have to come in the winter months.
Shift Pressures -> Downshift -> Oncoming Clutch
Removed: Update later
Shift Pressures -> Downshift -> Offcoming Clutch
Removed: Update later
NEW 8/6/22:
Downshifts: REMOVED, will update later with better information.
I have found that almost all the pressures in the stock tune are way too low. This is the opposite of the 6L80 tuning GM does where the pressures are set high and the adapts bring it down. The ZF8HP75 has the stock pressures low and the adapts increase pressures.
I'm having an issue with my 2019 challenger rt with the 5.7, in where is doesn't want to shift from 1st to 2nd during a wide open pull. I've tried increasing and decreasing torque management and nothing has worked. I've had other look at my tune but they couldn't find anything wrong. Everything I ask what it could be, everyone says the tune, but never how to fix.
I have it shifting at 5600 rpm, and last I was at the track it was shifting at 6700 rpm. not what I want. I have been messing around a little and think I might have found a solution? I've increased line pressure and torque reduction quite a bit and that seems to have helped, but I won't know for sure till I go back to the track
You might not have enough pressure in the upshift oncoming clutch pressure tables depending on how much power you added. There is a Flare Adder table (on the same tab) that adds more pressure the more it slips. I haven't actually played with the flare adder table and I'm not sure if there is a PID that shows it actually in action.
Torque Management -> Upshift -> Forced Torque Intervention
This is a turbine speed delta by engine trq map. After the shift has gone through and tries to apply line pressure at the end. If its botched and still cant make the hand off this is the map that kicks in and pulls trq to get the gear back in line. Its the final trq reduction and a last ditch hope. You see this usually as timing that doesn't come back right after a slip shift. I found out during the early days disabling some or all trq management cant remember but 4-5 slipper was the outcome with that table able to change how much timing at the end was held till the gear came in line.
I'll also add back in the infancy I played with shift time. I lowered it in the low trq areas and got my trans to damn near chirp tires cruising around without changing anything else. I also increased them and got slippy shifts. The thought process after that was the learning the trans does is also effected by it. IE you drag them out it will slow the adaptive pressure hand off. You shorten it the faster it will adaptive hand off. This was a long long time ago. Also before demon and red-eye cals the only bind up I ever had shifting was when I was lowering the line pressure trq axes numbers to bring in more line pressure earlier in the gears. This was with a max of 10bar wot shift first hand full of gears and 4 or 5 bar high trq last few gears on a 2.5 hellcat on e85.
im not sure either, and test and tunes i get 1, maybe 2 passes down the track so its hard to get it tuned right. but as for the flare adder i did increase it slightly just because i dont know how much pressure the trans can take. here is what i have in it right now, and what i went to the track with, maybe you can have some insight
Attachment 119951
Attachment 119952
What is actually happening when it doesn't shift from 1st to 2nd? I would correlate shift pressure to shift time more than the torque intervention. If you increase power on the clutches then you will need increased pressure to have the clutches engage at the same time. From what I can tell the ECU will always attempt to apply the torque reduction based on the shift time. I'm not sure what happens when you go past the physical limits of how quick timing can be pulled and pressure being applied to the clutches.
What happens if you manually shift near WOT RPM while only 50-75% throttle? Sometimes when I manually shift above the intended shift point it will bring out bad tuning that is easier to catch.
I updated my post above, I managed to finally tune out the damn bump felt near idle on the 3-2 and 2-1 downshifts especially when the idle is increased.
It just doesnt shift. It goes past the shift and doesnt try to shift. Ive gotten in the right direction now, it shifts, just instead of 5600, its 6700. Not great, but a step. Aslo i havent really tried using the manual shift in higher rpms, but i know at wot it still just shoots past the shift just like in auto
Thanks! I just reset all the transmission parameters to stock and realized I'm not actually resetting the adapts as much as I thought I was. The scanner seems to do a little bit to reset the adapts but its not a complete reset. I had a 1-2 shift I couldn't get the aggressiveness out and its now finally gone after 100+ miles of driving on the stock parameters. I've done every reset I could find in the scanner. I don't think we have the ability to do a 100% reset of the adapts and I haven't found a setting to disable adapts.
I do need to figure out how to detune/disable the aggression mapping as that will push your tune over the edge as I found out after having to drive to the hospital extremely fast the other day.