Field Report: Why Don't We MAX Out Torque Tables?

Speaker 1: 0:00

With a modern crop of factory engine management systems. Almost exclusively, these systems are now using a torque based tuning process. Now this can be a little bit hard for some of those tuners that are already familiar with tuning in the aftermarket to adapt to and get their heads around. We're here with Paul from Ecutech to find out a little bit more about torque based ECUs. Welcome to High Performance Academy's Tune In Field Report podcast series. In these special midweek episodes, we look back through our archives to find the best conversations we've had through years worth of attending the best automotive events across the globe. We've pulled the audio from these tech filled interviews with some of the industry's most well known figures and presented it in podcast format for you to enjoy as a quick hit of insider knowledge. Paul, before we get into torque based ECUs, let's actually roll back a little bit and talk about what was around in terms of the tuning strategy prior to that. What were OEs using before torque based tuning became the norm?

Speaker 2: 1:08

Primarily to adjust the power on a forced induction car, turbo car in particular. Whether this is most applicable, it would generally be a boost target that was linked to the throttle position. There wasn't any integration with, say, ignition and fuel, it was just everything else did what it did and the boost control was controlled by your right foot.

Speaker 1: 1:29

So essentially, from a tuning perspective, with that strategy, if we want more power and torque, we simply ask for more boost at wide open throttle. The ECU does the rest and as long as we keep our fuel and ignition mapping happy, we'll end up with what we ask for. Yes, pretty much Okay. So at what point in terms of a generation? I mean, I know there's not a black and white line in the sand. When did OEs start to move on with their strategies and move to torque based tuning?

Speaker 2: 1:55

I think in the mid 2000s we start to see really the introduction of drive by wire throttles, and that's really what started the torque revolution. The primary purpose early on was to be able to vary the power delivery based on the throttle position, or rather the pedal position, to give a different amount of throttle opening for different situations and then integrate with, for example, torque control for automatic transmission control.

Speaker 1: 2:21

Okay, so when the driver's foot pedal is no longer hard linked to the throttle because now we've got drive by wire, the computer can play a lot of little tricks in terms of depending what the driver's asking for, what the ECU actually delivers at the throttle body opening, correct?

Speaker 2: 2:38

That's right, and so that introduces torque control in a way that you wouldn't previously seen on a normally aspirated engine, which gives the manufacturer the facility to smooth the torque applications control, pickup torque from low speed control, have a sport mode and the eco mode, as well as all of the feedback into systems like the stability control and the ABS control.

Speaker 1: 3:02

OK. So there's a few elements there. I mean in terms of we're just looking at the outright torque that the engine's delivering. Then, as we mentioned, I mean from a tuning perspective. Previously we could do this with boost control, but now this gives the OE manufacturers a huge amount more control and this becomes, at least as I see it, increasingly important as we move away from conventional manual transmissions to the newer generation of automatic transmissions, but specifically DCT or DSG as well. So how does that play in in terms of the strategy for a dual clutch transmission to change gear? Why is the torque communication, tuned from the transmission control module and the engine control module, so critical?

Speaker 2: 3:43

There's a few aspects of that. It's most important, I would say, with a forced induction car, because you've also got the additional problem of handling the boost and the turbo control during shifting. From a drivability and reliability point of view, what we're looking to do is smooth out the torque delivery during the shift process, and so there we have all the inertia effects within the transmission that we've got to try and reduce the push or surge that you might otherwise get, and then, to enable the shift to happen, we have to cut the torque to allow the clutch changeover to occur, without trying to introduce the incoming clutch with a higher level of torque, which is going to lead to slip if it's done too soon before. We've managed to reduce the sort of slip to below, say, 50.

Speaker 1: 4:30

RPM. The other aspect of this is why we might not care at wide open throttle about the feel of the shift, the shift quality. This becomes really important at part throttle shifts as well, the smoothness of that torque reduction and reintroduction. If that's not done properly, then the person driving it is going to feel that correct.

Speaker 2: 4:47

Yeah, that's right. So, as you mentioned, as well as the in between the gears during the shift, then the power reintroduction is all integrated into looking to maintain a smooth, consistent level of torque at the wheels, regardless of what's ever happening at the engine through the transmission during the shift and all the other effects from slack in the transmission and so on that can turn up as drivability issues, not necessarily at full load as well, but also part load. And then you've got take off to consider.

Speaker 1: 5:17

Alright. So now we've got a bit of an idea of what the torque base tuning is and why OEs are doing it, or some of the reasons behind it. So, from our standpoint in the aftermarket, when we're faced with tuning some of these newer torque base issues, what are the complexities for the tuner? What tables do we have access to that need to be changed?

Speaker 2: 5:35

So typically it starts with a main torque request. So rather than a pedal position dialing up a kind of boost target that delivers a certain amount of power and it is what it is in this case what we're looking at is a pedal position that delivers a specific number for torque. You know, often you'll see the calibration be done in newton mesas and they're looking to deliver a certain torque curve and when you look at, say, for example, the difference between a sport and an eco mode, it becomes quite easy to specify. You know a low power mode because you just request less torque and somewhere else in the ECU all of those things are taken into account and the boost and the airflow are calculated and controlled to deliver the torque. But the important bit is the. The primary request is torque and not an airflow, not a boost figure or anything else.

Speaker 1: 6:30

So essentially we're asking for a torque value and then the ECU will decide what combination of boost pressure and throttle position is going to be required in order to deliver what you've asked for.

Speaker 2: 6:41

That's correct and it's not always the same across all sorts of ECU. Some will use a combination of adjusting the boost pressure. Some will try and run a more static boost and just the throttle, so it can vary. But the next step is when you want to increase the power from the stock calibration. It generally will always involve some level of asking for the increase in torque that you're trying to ultimately reach.

Speaker 1: 7:03

Do you want to take your car knowledge game to the next level? Join us in the next free lesson at hpacademycom slash free and start developing your own skills today. Now the obvious question here is well, okay, we've got access to this talk table. Let's just go in and max out these values and we're going to get as much talk as the engine can produce. So what's wrong with that strategy?

Speaker 2: 7:23

Well, that sounds good and to an extent you will see some sort of gain.

Speaker 2: 7:27

But in conjunction with that you're going to run into a whole load of talk limits and then at the next stage in that and a very important part of this whole process is that we will need to convert the talk request into some sort of airflow or load and then ultimately a boost request. And so what you'll typically find is that for a given talk request there will be a corresponding load level, but that will also be capped, and then to deliver that amount of load there will be either a calibrated or calculated boost pressure, and that will also be capped, and that might be capped as an absolute pressure. We might also have some limits turn up as a pressure ratio, so you might get some different effects at different altitudes for the same vehicle. From a OE tuning Point of view, you usually find that the vehicles suspect to be able to deliver their stated standard power at a wide range of altitudes, so there's usually some spare capacity in any given system. So increasing a number of these limits is also required sort of in conjunction with any talk request.

Speaker 1: 8:32

So if you don't go in and find and then raise the limits, just physically adjusting the talk request table might not actually allow the exterior to command that.

Speaker 2: 8:43

So you might go in and request a 30% increase in talk and you might get a 10% increase in talk, because then the next you're always subject to the lowest common denominator across all the limits on all the subsystems within the ECU.

Speaker 1: 8:57

So a little bit of detective work might be required to find out what, in particular, is bringing in these limits, but also a little bit of common sense in terms of understanding the limitations of the mechanical components as well, so that you are working safely and you are going to end up with more talk in a reliable form.

Speaker 2: 9:15

That's right. And what you'll see in the most modern ECUs is that there are safety limits in place for things like exhaust gas temperature. That will limit the talk. There are maybe some limitations on calculated combustion torque value, and so what you'll see is that each subsystem has its own limit. So there's a limit for pressure ratio, which is really to safeguard the compressor side of the turbo. There might be an absolute limit on boost, which is often similar to pressure ratio, but not always, and that might be designed with some of the induction hardware, maybe the turbo, but also the engine.

Speaker 2: 9:55

And then, of course, you've got you know, engine load, or often expressed as a sort of cylinder fill percentage, and that might be limited because of ultimate combustion pressure limits, and some ECUs even have a combustion pressure model that will also limit the load. So when we're trying to increase the power and calibrate these systems, what we at Ecutech try and encourage our tuners to do is really focus on why that limit exists and not just to max everything out and then sort of cap it on the boost. And there are applications where that might be applicable in some sort of maximum effort drag engine on an OEM ECU. But for the most part. If you have an upgraded turbo that still has some physical limitations that you can know about, you can still put those in and in ideal conditions you'll get maybe your calibrated torque. But in less than ideal conditions, where we have maybe high ambient temperatures, low ambient pressures, high exhaust temperatures, that safety systems can cut in and reduce the boost and load to save the engine.

Speaker 1: 10:58

I think in the aftermarket it is very tempting to sort of think we know best and maybe just blanket disregard all of the limiters. And, as you say, I mean the safety systems are there for a reason. So if you can calibrate, get your aim, your target, and still retain those safety parameters, as you mentioned there, they're there to protect the engine and the components in the case of subpar operating conditions like Altitude, as you mentioned. So I think, yeah, it's really important for tuners to actually understand what they're looking at and why a particular parameter or limit is there. And once an understanding has been made, then you can decide what actually needs to be done with it. Look, if people do want to find out more about the Ecutech product, where are they best to do so?

Speaker 2: 11:40

Paul, the best place is on our website, which is wwwecutechcom.

Speaker 1: 11:46

Perfect. Thanks for your time. Thanks, if you enjoyed this podcast. Please feel free to leave a review on whatever platform you've chosen to listen to it on. It goes a long way to help us getting the word out there. All these conversations, and much more, are also available in full on our High Performance Academy YouTube channel, so make sure you subscribe. It's a one stop shop when it comes to going faster, stopping quicker and cornering better.