Practical Transmission Tuning: Torque Converter Lockup Tuning

Back to course

Watch This Course

$199 USD

-OR-

Or 8 easy payments of only $24.88 Instant access. Easy checkout. No fees. Learn more

Enroll Now
8 easy payments of only $24.88

Course Access for Life

60 day money back guarantee

Torque Converter Lockup Tuning

1.12.25

00:00	All right, let's close our compare file, and we can close up these tables for now.
00:08	If I'm able to reach someone on HP Tuners and sort this out, I will.
00:12	Otherwise, I will make sure I leave things at safe values and be able to deliver the car to the customer, and hopefully they'll be satisfied with how it works.
00:26	Obviously, we have made it a little more peppy.
00:28	We haven't been able to get the level of control that we would expect typically from the HP Tuners platform, but sometimes there are so many applications that they support, and this probably isn't the most common of vehicles.
00:43	So, this may just be something that we are finding for the first time that can be sorted out in the future.
00:50	But nevertheless, good enough.
00:54	Okay, torque converter clutch.
00:58	All right, so this vehicle does have a stock torque converter, but we do have the torque converter clutch, which we have full control of, and we can determine when we lock it up and when we don't.
01:09	So, why do we want to lock up the converter? Typically, it's going to be for efficiency, whether it be for fuel economy or performance.
01:18	We want to get everything the engine delivers out to the drivetrain and do so in a situation where allowing the torque converter to slip and swing the engine up to a higher RPM isn't beneficial.
01:31	So, for example, that could be relatively low RPM where torque multiplication and allowing the engine speed to flare up will be beneficial if we wanted max acceleration.
01:43	Then we might want to unlock the converter, but if we're at low RPM and we're cruising, like let's say on the highway, now we probably want it locked up.
01:51	We just want good fuel economy.
01:54	So, let's take a look and see how this is set up from the factory.
01:59	All right, so I'm going to pull up.
02:01	Again, we've got normal and pattern A, and from what I can see here, 318 mile an hour, again, common value used in this particular ROM just to move something out of the way, right? So, if the minimum vehicle speed to apply the torque converter lockup clutch in first, second, and third gear is 318 miles an hour, we will never get there.
02:27	This is set up to not lock the torque converter clutch up in first through third gear.
02:33	Then, in fourth gear, varying with vehicle speed and throttle position, we might lock up the converter.
02:43	Looks like the values are very drastically different between normal and pattern A in our sport mode.
02:53	So, unlike the shift scheduling where the differences between the two are relatively small, here it's pretty massive.
02:57	So, in the sport mode, we're going to have to be up to a much higher vehicle speed, much higher engine speed before we lock the converter, and that's going to give us that extra snappy engine response and performance.
03:09	So, this looks fantastic.
03:11	I really like what they've done there.
03:14	And then, let's look at what happens in fifth and sixth gear.
03:17	I'm expecting to see the converter locked up more because those are gears we're typically going to be cruising in.
03:23	So, let's pull up normal and pattern A fifth gear.
03:31	Okay, so much like the sport shift mode was pretty sporty from the factory, going from first to second to third to fourth, and then kind of chilled out, became more casual, and started shifting sooner, keeping the engine speed lower in fifth and sixth, it looks like they've done something kind of similar with the torque converter clutch lockup.
03:51	And what I mean by that is the normal mode and the sport mode are almost identical at low throttle positions, same while coasting, and then at light throttle, very, very similar.
04:07	Now, let's see what happens in the mid -range.
04:09	Let's see if that starts to change.
04:10	So, at 25% throttle, I'm seeing 60 on the normal table and a 65 here.
04:19	So, a little bit of a disparity there.
04:21	Then at 31, we've got 70 versus 79.
04:24	All right.
04:24	So, kind of like in the shift schedule table, once you get up to more moderate accelerator pedal or throttle position, then you start to see more of a sporty response from the sport mode versus the normal mode.
04:39	And then it looks like by the time we get up to, let's say, 62, these numbers are quite high and far less likely to come into play.
04:52	So, let's make sure we're looking at the same units everywhere.
04:58	I noticed that head got bumped.
05:00	Okay.
05:04	So, yeah, it looks like in fifth and sixth gear, if you're cruising, we're going to be probably locked up, whether we're in normal or sport.
05:13	But if you're at moderate throttle, more likely to unlock the converter clutch in sport mode versus normal mode.
05:20	Also, you're going to have to be at a higher vehicle speed in both modes before the torque converter clutch will lock up as you apply more throttle.
05:30	So, let's think about what we might want to change here, just to show you guys an example.
05:38	So, one thing we might want to do, and I think this is just for the sake of showing a possibility of what you might want to be able to adjust.
05:50	Let's say, you know, from the factory, they're not going to apply the torque converter clutch in third gear.
05:55	Maybe we want to do that.
05:58	Maybe that's something that we want to do.
06:00	So, in that case, you could possibly set some values that make sense here, like 30 to 80, maybe 70 here, interpolate those down.
06:21	Yeah, we don't really want these to be higher than the higher gear, so let's not do that.
06:25	Let's do 30s here to You could do something like that.
06:41	You know, maybe you want to try that, see how that works.
06:44	But before doing that, if you just want to make sure that the torque converter clutch is allowed by the system's logic to lock up at all while you're in third gear, you probably want to do something simple like, you know, let's set it to 20 miles an hour and get the vehicle up over that and just make sure that the converter engages.
07:07	So, let's start simple.
07:08	We'll just start with that.
07:12	All right, I'm going to increment our version, and we're going to start calling this TCC lock one.
07:27	And we are just doing this again in, let's see, yeah, just pattern A.
07:39	Okay, so I'll try to keep my naming convention consistent here for clarity.
07:48	Okay.
07:53	All right, we are disconnected from the scanner.
07:57	Key off, key on.
08:00	Let's flash only the TCM.
08:15	And then I'll just get the vehicle up into third gear, make sure it's over 20 miles an hour, and we should see the torque converter lock up.
08:23	We should be able to see that in terms of the torque converter line pressure that's being applied to it, as well as the torque converter clutch slip measurement should drop when the converter locks up.
08:35	So, that's what I'm going to be looking for just to confirm that it's doing what we want.
08:39	We really just want to make sure that when we make that change, we're getting the lock up we're expecting.
08:43	So, let's go down here.
08:46	We're in pattern A, which is where I've made the change.
08:51	Torque converter clutch slip is here.
08:55	Desired slip is here.
08:57	It's probably zero right now because that system is just not active.
09:00	It's not trying to lock up the converter.
09:04	And let's get rolling.
09:13	All right, so we're over 20 miles an hour.
09:15	Let's see what happens when we get into third gear.
09:21	All right, I did not see it lock up.
09:26	So, let's slow down.
09:27	Let's get back into third gear.
09:34	And now I am actually going to use the dyno to help me out here, make it a little easier for me to control what's happening.
09:41	So, we'll get into third.
09:50	I'm going to bring the speed of the dyno down until we downshift into third.
10:07	All right, so we're at 25 miles an hour in third gear.
10:15	Torque converter should be locked up, but it's slipping over 60 rpm with a desired slip level of 40.
10:24	Our TCC line pressure is zero.
10:27	So, we are definitely not locking up.
10:32	I can also see TCC PWM duty cycle is zero.
10:36	So, I think it's pretty safe to say we're not locking up the converter right now, even though we probably should be given our settings.
10:43	So, I'm going to let the engine rev up a little more, get into fourth gear, and let's see what converter lockup actually looks like.
10:55	So, now let's go all the way to fifth or sixth gear here.
11:12	All right, fifth gear.
11:15	Sixth gear.
11:18	Okay.
11:18	So, now we've got line pressure to the torque converter of 31 psi, 32 psi.
11:26	We have a little bit of slip in the 40s and 50s, but it looks like the desired slip that the ECU is tuned for is about TCC PWM duty cycle is reading zero, but I suspect that is perhaps not functioning properly, given that we have line pressure and it looks like we've got a converter that's locking up.
11:51	But let's just do a quick test here.
11:54	I'm going to go in here to transmission, torque converter clutch, and let's see what happens when I manually force the converter to lock.
12:04	Now, this is going to cause a change for sure, almost definitely, because this is going to apply full line pressure to the torque converter clutch.
12:13	Normally, in a situation like this, the converter clutch is pulsed in a manner that provides a bit of lockup, reduces torque converter slip without being fully maxed out.
12:25	So, the line pressure is probably going to jump up when I do this, but let's see how far it goes up.
12:31	Okay.
12:32	So, it's gone up to 594 psi, quite high.
12:37	Our torque converter slip is now effectively zero because we have tons of pressure clamping it.
12:43	So, this is certainly working.
12:49	And I think what we're seeing right now is it's kind of starting to adapt.
12:55	As I mentioned earlier, there are adaptives in this transmission, both for shift pressures to make shift times line up better with the calibration.
13:04	It also has them for torque converter clutch.
13:06	So, if it sees that the desired slip is 56 and we're slightly over it, it might make a slight change to the line pressure over time just to get that dead on where it should be.
13:18	But, I mean, it's pretty much doing what we want it to do.
13:21	I'm just going to apply a little more throttle and see what that does.
13:27	You can hear the engine note change.
13:29	It just came out of displacement on demand as I applied more throttle.
13:34	So, yeah.
13:35	So, as I'm applying more torque, torque's now up to 200 foot-pounds.
13:39	Now, the line pressure of the torque converter clutch is ramping up, which is allowing it to the slip right around the desired value.
13:47	So, safe to say the torque converter clutch is definitely working in sixth gear.
13:51	I'm going to back down.
13:57	So, why didn't we get the lockup we commanded in third gear? I don't know.
14:05	Let's take a look.
14:11	All right.
14:13	Simplify.
14:18	I'm pretty confident that we're in pattern A because it says we're in pattern A.
14:24	But, maybe within a torque converter clutch system, maybe the tables aren't defining quite the same way.
14:31	So, what I'm going to do is I'm going to apply that same change to normal mode.
14:35	And we'll still run the car in sport mode after I flash this.
14:38	But just in case something's going on with that, we'll just see if that makes a difference.
14:44	All right.
14:45	Pattern B, again, looks like it's not used.
14:47	Okay.
14:48	So, these values are all set in a manner where they would never do anything.
14:52	Safe to say pattern B is not in use.
14:55	Okay.
14:55	When the transmission is hot, the torque converter is going to be applied in second, third, and fourth if we're over these speeds.
15:04	So, if this is set up this way, we know it's certainly possible, again, for the torque converter clutch to be locked up while the vehicle is in those gears.
15:12	We've done it manually using the VCM scanner suite.
15:17	But this mode is certainly going to do it.
15:19	Reason for that, when the transmission is hot, is anything that reduces slip is going to be beneficial in bringing temperatures down.
15:26	All right.
15:27	In tap up, tap down, again, third gear, torque converter clutch is being locked up.
15:35	The reason for that in tap up, tap down is just to make the car feel more like a manual transmission, make you have more of a direct relationship between engine speed and what the transmission is doing.
15:47	So, that makes sense.
15:49	All right.
15:52	Let's look at full throttle.
15:58	Safe to say that was not coming into play when I initially tested and was at very light throttle.
16:09	All right.
16:11	Let's go back to where I was in third gear.
16:14	Yeah.
16:15	So, here I'm at 25 miles an hour.
16:17	I am at accelerator pedal position of 10%, throttle position 24.
16:23	We're definitely not at full throttle.
16:27	So, that shouldn't have been preventing us from getting torque converter clutch lock up.
16:33	But given that this is the only other table that seems possibly even remotely relevant, I think it's time we gave it a shot.
16:45	The other thing I'm going to do here is I'm going to reduce the desired slip in third gear.
16:57	And that way the TCM is going to attempt to achieve less slip.
17:07	So, let's go for a little less slip in the other gears as well.
17:19	Might make the vehicle feel slightly more direct.
17:28	There might be a slight increase in noise vibration and harshness.
17:32	Maybe not.
17:35	But I'm curious to see what that will feel like on this particular vehicle.
17:39	So, let's give it a shot.
17:41	One thing I'm going to do a little differently here is I'm going to leave the real low RPM area alone.
17:50	Just in case we somehow end up down there and for whatever reason the torque converter clutch hasn't released.
17:55	We want some slip.
17:57	We can pretty much guarantee it's going to release before it gets down to a really low RPM though.
18:03	Otherwise, we would be stalling and we are not.
18:06	So, okay.
18:09	We'll do that.
18:10	I'm not going to touch first and second gear tables because we're not trying to lock it up there anyway.
18:15	Minimum slip with the AC on.
18:17	I'm going to drop down to 10 RPM.
18:20	Do have the HVAC system on right now.
18:23	So, that might come into play.
18:26	I'm going to tell it for now to not do different slip targets while displacement on demand is active.
18:33	Just to avoid that potentially confusing our investigation here.
18:40	High speed systems are well out of the way.
18:42	Not going to come into play.
18:46	And I think we are pretty well ready to go.
18:52	Let's just check some other settings.
19:03	Okay.
19:03	We'll come back to this one in a bit.
19:05	This might come in handy.
19:09	All right.
19:10	So, again, we've made a change to normal mode so that normal torque converter clutch settings match sport or pattern A torque converter clutch settings.
19:20	Just in case, even though we're operating in sport or pattern A, perhaps within the torque converter clutch system the table definitions are such that the other table is actually the one that's active in this situation.
19:35	So, this test is just here to see if that's the case.
19:44	And while this won't completely determine that, if we still have the same behavior, then it's safe to say that neither of these tables are going to allow us to lock up the converter clutch in third gear.
19:57	So, let's go for third.
20:04	All right.
20:11	Second gear.
20:27	All right.
20:27	So, I basically want to be at a vehicle speed where I'm solidly in third gear, but it's not going to upshift to fourth gear without having to change my shift scheduling settings.
20:38	So, I've done that now.
20:40	We're in third.
20:42	It's not looking like we're locked up again.
20:45	We're well over the vehicle speed at which it should be locked up.
20:49	I'm going to try everything from low engine torque amounts to higher ones.
20:57	Here again, the TCC desired slip is zero, which I generally see either when you have literally selected zero or when the system is not actually attempting to lock up.
21:12	So, what I sometimes do is rather than set a zero on the table, I'll set it to one, which effectively will do about the same thing, but then when I'm looking at the real -time data or data log data, it makes it easy for me to see whether it was actually commanding one or it's saying zero because the system isn't trying to lock up right now.
21:31	So, anyway, we've got a good amount of slip.
21:35	I'm out of displacement on demand.
21:38	Torque converter slip just keeps going up because it's not locking up and I'm applying more torque.
21:44	This all makes sense.
21:45	The fact that it's not locked up is what doesn't make sense.
21:48	We have no line pressure to the torque converter clutch and I'm not going to keep slipping the converter, so I'm just going to back out of it.
21:56	Again, remember that builds a bunch of heat.
21:59	We don't need to be doing that for any significant period of time.
22:02	We don't want to beat it up.
22:04	I'm just going to do one last thing to show you what happens when there is a decent amount of slip and you go ahead and manually force the clutch on.
22:14	So let's get back up into third gear in that situation.
22:20	All right, so I don't want a ton of slip when I lock this thing up because I don't want it to slam, but I want it to be enough that you just kind of get to feel it along with me here.
22:31	All right, so we're going to make a little bit more slip and now lock it up.
22:36	And the slip goes away, right? So because I'm doing this manually, you're not seeing a desired slip value necessarily, but we're getting a bunch of line pressure to the torque converter lock -up clutch.
22:47	It's locked things up.
22:49	We are locked.
22:51	Unlock.
22:53	And that brings us back to our normal strategy.
22:56	All right, so we've done what we can do there.
23:02	Now, had everything been working as expected, the torque converter clutch would have been locked up at that vehicle speed because we are over the 20 miles per hour that we set to apply the torque converter lock-up clutch in third gear in both the normal and pattern A mode.
23:25	So the test should have worked in either pattern A or normal.
23:28	I did it in pattern A.
23:30	You know what? Let's just quick do it in normal just in case that miraculously works.
23:43	Ah, so now we're running into different shift scheduling.
23:47	So it put me into fourth gear at that same vehicle speed I had been using before in third.
23:53	So we're just going to need to adjust things a little bit, make that work.
23:57	So we need to be solidly over 20, but not high enough for a fourth gear shift.
24:03	Let's try it again.
24:08	All right, so 22 miles an hour and same situation.
24:17	We've got slip, we've got no line pressure, and we are in normal mode.
24:22	All right, so we've tested both modes.
24:24	We've done what we can.
24:29	And we will save that.
24:31	That's going to be the same name as this, but normal mode.
24:38	Okay, at this point, let's revert these values to stock in this area.
24:52	And I'm going to do that by comparing, showing the differences, making the differences zero.
25:00	All right, that was just a 318 there.
25:03	So we're going to paste that in these two.
25:07	And that gets us back to where we were.
25:09	Okay, so let's see what fourth gear is doing.
25:13	Let's see if fourth gear is behaving as we expect it to, based on this.
25:19	Now, in order to do that, I'm actually going to use the tap up tap down tables, just to show you something a little different.
25:28	So let's do fourth gear.
25:32	And I'm going to use 50 miles an hour for apply, and 40 miles an hour for release.
25:47	I'm only going to set up fourth gear.
25:50	We're only going to test in fourth gear.
25:52	And because it's in tap down tap mode, tap up tap down mode, we can just put the car in fourth, piece of cake, and test like that.
26:01	So let's go ahead and do that.
26:04	All right.
26:09	This is going to be TUTD, TCC log three.
26:16	Perfect.
26:22	All right, so we are fired up.
26:24	We're going to be using tap up tap down mode for this test.
26:27	And what we're expecting to see is in fourth gear, for over 50 miles an hour, I'm expecting the torque converter clutch to start to lock up, and then vary depending on the slip encountered at the time.
26:39	And then if I drop down below 40 miles an hour, I'm expecting it to disengage.
26:43	So as I ramp up from 40 to 50, it'll be disengaged.
26:47	Then when we get to 50, I expect it to engage.
26:50	But then if I slow down to between 40 and 50, it will remain applied until we get down to 40, where it's going to release.
26:59	So that is how I expect this table to work.
27:02	And let's see what happens in practice.
27:09	All right.
27:13	I'm going to move my steady state RPM on the dyno up out of the way so that doesn't interfere with our tests.
27:28	All right.
27:29	We are now in tap up tap down mode.
27:32	We are at 60 miles per hour.
27:36	And we have torque converter clutch line pressure.
27:39	And we have torque converter slip, which is less than desired slip.
27:44	This looks fantastic.
27:45	So I'm gradually slowing down now.
27:49	We've dropped below 50.
27:51	We're still maintaining line pressure.
27:54	Torque converter clutch is still locked up.
27:57	I'm just going to continue slowing.
28:01	Try to hit 40 as slowly as I can just to show you that it should click off at that moment.
28:08	All right.
28:09	We're at 40.
28:10	Let's go for 39 and see if it turns off.
28:13	Yep.
28:14	So right as we drop below that release value, that's when the torque converter clutch disengaged.
28:19	So happy to see that that's all working as expected.
28:23	Still unclear why everything works perfectly in fourth gear but not in third.
28:30	But certainly everything should work as I've just demoed it to you in all situations unless there's a perhaps an issue with the definition of the particular ROM that you're working with and in your software package.
28:46	Okay.
28:46	So now that we have done that and confirmed this is working beautifully, I'm going to save this.
29:05	All right.
29:07	Okay.
29:07	Back here that test was fantastic as a demo but what I'm going to do is revert those settings back.
29:17	I like tap up tap down the way it is for now.
29:20	We're just going to leave that be.
29:22	But if you want to make a change in say pattern A, for example, anytime you're under 50 miles an hour you want the converter clutch to release, you could perhaps grab these values that are over 50, set them to 50, and you can get a similar sort of change.
29:49	I do like having this trend here because it will effectively make the converter less likely to unlock if you're applying more gentle throttle and that'll be more likely to keep it locked when you're just driving casually.
30:04	It'll give you great fuel economy and efficiency and that's when you really want the converter clutch locked up to help you out.
30:12	So I like that trend here but perhaps you know under that vehicle speed you just decide you want it unlocked.
30:21	Now there is one other very specific consideration in terms of torque converter clutch lockup which is important if you have a let's say heads and cam package that is not particularly happy at low engine speeds.
30:36	Okay so if the heads cam package works phenomenal at 7,000 rpm but doesn't cause the smoothest of combustion at let's say 1 ,800 rpm, one thing you may want to do is make sure you keep the torque converter clutch unlocked at vehicle speeds that would correlate with that rpm range of the motor and what that will do is it will allow the engine to basically rev up out of that area if you apply enough throttle due to torque converter slip or simply provide some decoupling between the engine and the drivetrain a little bit of a buffer there so that as the engine pulses aren't perhaps perfectly smooth you aren't feeling all of that through the drivetrain which could feel like you know maybe not bucking but perhaps a less smooth feeling than you might desire.
31:33	All right so little tidbit there just an example of why you might want that or not.