122 | The Key to Road Tuning - Left Foot Braking
While the dyno is undoubtedly the best place to perform your tuning, some cities and even some countries have no access to a local dyno. In these situations you have no option but to perform your tuning on the road. In this webinar we’ll cover a few of the basics of road tuning, including the technique of left foot braking, and how we can deal with tuning ignition timing with no torque feedback.
It's Andre from the High Performance Academy. Welcome to this webinar where we're going to be discussing some of the concepts of road tuning. Now, before I get started, I know that at the moment I am sitting in our Nissan 350Z and I'm clearly sitting on our Mainline chassis dyno. However, don't worry, we are, in fact, going to be talking about the principles of road tuning and I'm going to show you at least as far as I can, how these apply on our dyno. Unfortunately, it's not so easy for us to actually go out in the real world and produce one of these live webinars, and air it while we're driving around on the streets.
So we'll have to suffice with the dyno, but I think it's going to do a great job of demonstrating the techniques that I want to show you anyway. Now, before we move into that though, let's just talk about road tuning, because this is a topic that is very, very popular and the ideas on road tuning versus dyno tuning are very, very divided. There's those that think that the only place that we can possibly tune a car is on a dyno. Then there's those that spend their time road tuning who believe that dynos are a waste of time and can give inaccurate results. Now, I think I sit somewhere in between and the reason for that is obviously we have access here to a quality chassis dyno and I've been fortunate enough that over the years of my career I've always had access to good quality dynos and I've seen how to get the best out of cars on the dyno.
That being said, I know that we have many members that come from cities and even countries in the world where there are no local dynos and this becomes a problem. Now, obviously while in the perfect world, the dyno is the best place to perform your tuning, if you have no access to a local dyno then you may have no option but to perform your tuning out on the road or the racetrack out in the real world. Now, while that may seem a little bit scary there are some big advantages, in my opinion, to actually tuning out on the road and I think these are often overlooked in discussions about road tuning versus dyno tuning. I'll rewind a little bit. At the beginning of my career I was just getting started and at the time I was renting dyno time on a two wheel drive Dynapack Chassis dyno.
Now, that was all we had local access to then and if I wanted a four wheel drive dyno I was looking at around about an eight hour drive to get to the closest four wheel drive dyno and at that particular point in my career I was tuning a lot of two wheel drive cars which made a lot of sense. That was fine on the two wheel drive dyno we had access to. However, I also got involved quite heavily in rallying and I was supporting a few teams. I was crew chief for one of our local New Zealand rally championship teams and obviously if you wanted to be competitive in our New Zealand rally championship four wheel drive was the best option and so at that time I was tuning a number of four wheel drive rally cars. Obviously with no access to a four wheel drive dyno I was thrown in the deep end pretty quick.
So over the first year or perhaps 18 months of my career before we did gain access to a local four wheel drive dyno I spent a lot of my time learning out on the road how to get the best performance out of these cars without the benefit of a dyno. Now, I just wanted to touch on the advantages and as I said the advantages, I think, in road tuning are often overlooked, particularly by those who have access to a dyno, but they are very real, and they are very important. One of the main things I find is that despite the quality of the dyno and despite the quality of the dyno installation it is very, very difficult, if not impossible to accurately replicate the kind of air flow, the kind of pressures, the kind of temperatures, that we're actually going to see in the car when we're out on the road, or the racetrack, we're in perhaps fourth gear, we may be coming up to 200 kilometers an hour and we've got our foot flat. It's very expensive and difficult to replicate that sort of air flow in a dyno cell certainly at the hobbyist and semi-professional level that we tend to deal with. So what does this mean? What it means is that the tune that we see when we're on the dyno may be slightly different when we get out into the real world and we check our tune on the road or the racetrack under those sorts of conditions, again, simply because the actual operating conditions for the engine may be slightly different to what we saw on the dyno.
This can add up to a situation where the air fuel ratio that we see during a full throttle ramp run on the dyno may be very slightly different to what we see in the real world. Likewise, we may pull a car off the dyno that has been perfect and completely knock free in operation in terms of its ignition timing, however, when we get it out on the road or the racetrack, we may find that under certain conditions that engine may actually be more sensitive or prone to detonation or knock the way that the car is being loaded on the road may be slightly different to what we did on the dyno. Conversely we might have the exact opposite situation occur where the engine or the car will actually accept more boost or more ignition timing out on the road due to better air flow, cooler intake air temperatures, cooler engine operating temperatures, and things like that. So there's a number of aspects that we need to keep in mind there. Slightly off the topic of our fuel and ignition tuning, but particularly when we're dealing with turbo charged cars boost control is a really, really important aspect to consider and often what I've found is that I'll be able to get perfect boost results on the dyno, an absolutely perfectly flat boost curve that does exactly what I want it to do yet out in the real world, due to the way that the car is loaded, et cetera, we may find that the boost may be slightly different.
Maybe it's a little bit higher, maybe a little bit lower. Perhaps it's a slightly less stable, and we need to do some work to that area. The last aspect that I wanted to touch on as well is our light throttle area of our mapping. Now, this includes both our fuel and our ignition tables, however, it's probably most important when we're talking about our ignition, sorry, our fuel tables. What we find is that when we're tuning on a dyno in steady state it takes a reasonable amount, or a certain amount, of engine torque to maintain a certain road speed and what happens is that we need a certain throttle opening to achieve that.
This results in a specific manifold pressure. This becomes the lowest point in our fuel, in our ignition tables that we're able to competently access and tune in steady state. What happens is if we try and close our throttle down to reduce the manifold pressure further and access lower load sites, the engine simply doesn't make enough torque and the engine slows down on the dyno so this makes it impossible for us to adequately access and tune the very, very light load areas of our fuel map and of course our ignition mapss, too. Now, some tuners will say, "Well, that doesn't matter because exactly the same scenario is going to happen out on the road when we're driving the car in the real world," and to a degree that is true. However, when we are tuning on the road or driving on the road there are some slight differences.
First of all, on the dyno we have very, very little inertia involved with the dyno, and this is why when we close the throttle, the car, or the engine almost instantly slows down. On the road, however, we've got the inertia of the car actually rolling on the road, so this tends to, even if we close our throttle, tends to maintain a certain amount of engine speed. So what we can get into is a scenario where we're only just barely touching the throttle on the road, maybe we're rolling down a slight incline and we've backed almost completely off the throttle, and this may allow us to move down into a lower load site than what we were adequately able to achieve on the dyno, and what we can find is that in a car that's only been tuned in steady state on the dyno the air fuel ratio in these areas may be incorrect. Now, I'll be the first to admit this does get to a position where we're starting to split hairs. This isn't an area we're going to access often.
Often it is an area that we're only going to be transitioning through, but I tend to be quite fussy and I want to know that my tune is as accurate as possible. Often if these areas aren't addressed what we can find is that the car, the engine, will feel slightly hesitant out on the road, and very, very light throttle conditions as we're backing off and we're just transitioning into over run fuel cut. We're coming completely out of the throttle. So these are an area that we can access on the road and this is why, even with access to a quality four wheel drive rolling road dyno like our Mainline, I still, wherever possible, will take the car out on the road and confirm that everything I saw on the dyno is accurate, so this includes checking that my mixtures on the cruise conditions are correct, that I'm still meeting my air fuel ratio targets under cruise, generally that would be Lambda one where I'm trying to get really good fuel economy. I also want to check on the wide open throttle acceleration, so full power acceleration that the air fuel ratio is exactly what I saw on the dyno and also that my engine is not suffering from knock.
If it's turbo charged, obviously I'm checking my boost response, and then we can also tune and optimize those light throttle areas of our fuel table, make sure that those are absolutely perfect. One more aspect that we can do on the dyno, we've got a number of webinars in the archive that you can check out that cover this, and that's acceleration enrichment transient enrichment tuning. While we can do this to a degree on the dyno, as I explain in those webinars in the archive, while I am using the air fuel ratio or Lambda input as a guide to my transient enrichment tuning, really I'm going to be taking more of a cue from how the engine responds, so that's much more important to me, so I'm really looking for crisp response from the engine when I go to full throttle. I'm looking for something that's crisp. I don't want any lag or hesitation.
I don't want the engine to be sort of coughing before it catches its breath and actually accelerates. Sometimes that's quite difficult to get a really good feel for on a chassis dyno, so again, because a lot of this is masked by the lack of inertia on the dyno, and on the road we've got real conditions that we can test under. So hopefully, that gives you some insight into the advantages that are often glossed over with road tuning and why I'm a strong advocate for making sure that once we've completed our tune on the dyno that we do also test in the real world and I think it's probably reasonable to understand that this is also the technique that OE manufacturers go through as well. Not all of their testing is done on the dyno. Not all of their tuning is done on the dyno, and they'll have engineers or calibration engineers all around the world going through months, if not years, of real world testing under different temperatures and different altitude conditions to confirm that their dyno calibrations were in fact accurate and whether or not anything else needs to be adjusted.
Okay, so we've talked about the advantages. Obviously it's not all great news, though, if we are only able to tune on the road, and one of the biggest disadvantages that we have there is on the road we, understandably, have no torque feedback, so we don't really have a good idea as to whether the changes that we're making to our tuning are going in the right direction or not. While, yes, that's possible by the seat of the pants to get some indication of whether we're making more power or less power, there's a limit to how sensitive we can be and realistically, most tuners would struggle to tell the difference of perhaps anything less than about five to ten horsepower. Probably in reality, most tuners would struggle to be even that accurate so relying on your seat of the pants is not a very good way of sort of deciding whether you're going the right way or not. Now, this is more important though when we're dealing with our ignition tuning.
So this is really where we're looking for our MBT timing. We're looking to the dyno torque feedback to decide whether or not our ignition timing is optimal. So this is the area where we're going to struggle out on the road. Now this isn't really the sole focus of today's webinar. Really what I want to focus my energy on mainly is how to steady state tune on the road using the left foot braking technique but it is important to also talk about how we get around this ignition tuning, so I just want to touch on that briefly here.
Now, in some instances, if we are going to be performing our tuning on the road, and that's all we've got available to us, then we are going to have to accept that we may be making some compromises with our tuning, particularly as it comes to our ignition timing, and the reason for that is we have no idea, strictly speaking, where MBT is and understandably, if we're in that situation we need to apply a little bit of common sense and be a little bit conservative with our timing. An area that's important to understand, and this is my own opinion, or findings, I guess, from probably the better part, now, of 15 years of tuning cars professionally, is that probably greater than about 85% of the cars that I tune on pump fuel and certainly by far the majority of turbo charged or super charged engines that I tune on pump fuel, are what I refer to as knock limited. What this means is that the octane rating or the quality of the pump fuel that they're running on is insufficient for the application and this means that when we are optimizing the ignition timing under wide open throttle conditions we're actually going to end up encountering detonational knock before we reach MBT. What I mean by this is if we're running the car and we're advancing the timing, we're going to see the torque increase every time we advance the timing but we're also, if we're audibly listening for knock, we're going to reach the onset of detonation while we're still seeing that torque increase. Now, obviously at any time where we encounter knock, we need to instantly stop and we also need to retard the timing to provide a buffer or a cushion, a safety margin, from the timing the engine actually runs, to the timing where knock occurs.
Now, depending on the application, we may need to keep a safety margin of perhaps something like two or three degrees. Maybe a little bit more depending on how hard the engine is going to be used. Now the point of this conversation though, is when we're tuning the ignition timing on a knock limited car, provided we are obviously listening audibly for knock, that knock threshold becomes our limitation, and then under those conditions, regardless whether we are tuning on the road or the dyno, we're going to end up with a very similar ignition curves because of that knock limit, and understandably, under those conditions it's fair to expect that we're going to see very, very similar power levels, regardless whether the car was tuned on the dyno or out on the road, and I'll just rewind again to my, the beginning of my career with the four wheel drive rally cars that I talked about. At that particular point these cars were running on either pump fuel or avgas, which in my opinion is really no better than a normal octane pump fuel, 98 octane that we have access to here in New Zealand. Either way, the cars that I was involved with, these were, at that time, generation sort of Evo 5, Evo 4, Mitsubishi Lancer, and also GC8 Subaru STI.
These cars were definitely knock limited despite the fact they were breathing through a restricter on the inlet to the turbocharger. What I found was once we actually had access to a local dyno I got the opportunity to run up a few of these cars that I had tuned on the road. How often the results were within a few percent of what I could actually achieve on the dyno, so don't think that there is no way of getting good results on the road. The other aspect that's important to cover off here is just the way that I know road tuning is used by a lot of HPA members out there, so particularly those who may be enthusiasts or just getting started in their career, and don't have their own dyno. Now obviously, hiring dyno time can be quite expensive and particularly when you're just learning to tune, teaching yourself how to tune on your own car, often a tank of fuel and a weekend spent out on the road is a really cheap way of learning a lot.
So often what we can do there is use the road tuning techniques. In order to get our tune really, really close out on the road and our only cost there, as I say, is fuel and our own time. Once we've got the tune really close, then it's possible to hire maybe one or two hours of dyno time, and put that dyno time to really good use, to be able to focus solely on getting our ignition tables really optimally dialed in. This can save a lot of time and hence a lot of expense over performing your entire tune from start to finish out on a dyno from the start. Okay.
So today's lesson, what we're going to look at with our left foot braking is probably more predominantly focused on standalone after market engine management tuning where we need to perform steady state tuning. However, if we are re-flashing a factory or OE ECU and we're making large wholesale changes to the engine design, perhaps fitting a large cam shaft with a lot more overlap, a lot more duration than stock, then we may still need to use these techniques to correctly calibrate the mass airflow sensor curve Or the speed density subsystem depending on how our ECU works. So, that's probably enough talking from me about the background on this. What I'm going to do is just get our 350Z up and running and we'll go across, I'll just get our ECU online and we can jump across to my laptop software. So what we're going to do here is have a quick look at how we can tune in steady state without the use of the dyno.
Now, obviously, yes, we are on the dyno, but just to show that I'm not going to cheat, if we jump across to our dyno screen here, what we can see here on the top left gauge is our speed control for our dyno, and the yellow needle here is showing that we've got a control speed of 100 kilometers an hour, so what I'll do just while I'm talking I'll just get us running in fourth gear, and you'll see there as the wheels start turning our speed comes up. So normally what we would do is we would use the dyno's set speed in order to control our engine RPM. So you can see I've put our set speed down to 65 kilometers an hour, and our engine is now running in fourth gear at 65 kilometers an hour. What that results in on my laptop screen, if we can just briefly look at our laptop screen, is we're sitting at around about 2,500 RPM and this gives me the benefit that I can open my throttle and I can move very, very accurately through that 2,500 RPM column, so I don't need to worry about the dyno, what the dyno is doing is it's simply applying more load as I put my foot down further, so we can see right now I'm sitting at 100% throttle, and then conversely, as I close my throttle down the dyno reduces the load being applied to the rear wheels through the power absorber module and controls our engine RPM. So this is how I can use the dyno to tune in steady state.
Okay, let's jump back across to the dyno now, and just again, just to show I'm not cheating, what I'm going to do is I'm going to take our set speed all the way around to 240 kilometers an hour. So at the moment the dyno is providing me nothing other than a set of rollers for the rear wheels to turn on and there's really very little inertia with the dyno, so if we jump back to my laptop software, let's have a quick look at what we've got going on here. We can see at the moment I'm sitting at 13% throttle and we can see that if we look at our current point in our map we're sitting at about 2,500 RPM. Now just to show that there is no inertia, and this is a little bit exaggerated over what we'll see on the road, if I open the throttle, you see as soon as I open the throttle we don't really get very much load being applied because there's no inertia and the engine simply accelerates and that's kind of the same scenario that we have happening on the road. When we're out on the road, if we are in the cruise areas of our map, which may be exactly where we are right now, depending on the gear we're in and depending exactly on the incline of the road, whether we're on a flat piece of road, whether we're going uphill or downhill, this will give us the opportunity to quite accurately tune a range of cells.
Perhaps in this case around about that 2,000 through to 3,000 RPM range. I could just move through that range. I'm going to be able to get a lot of hits in those cells and I'm going to be able to do a reasonably good job of adjusting the fueling in those cells. You can see as I close the throttle, though, just close the throttle, you can see our RPM drops down. So it's very, very difficult for us to stay stable.
So when we're generally tuning on the road this allows us to do three things reasonably well. We can obviously tune our idle condition really easily because we're going to spend a lot of time idling, so we'll be able to come back down into these cells down here, around 800 RPM, maybe minus 70 KPA, and we're going to be able to dial those cells in quickly and accurately. We're also going to be able to spend a lot of time on these cruise areas which we just talked about. We're going to be able to dial those in. We're also, obviously, going to be able to tune under full throttle, and by choosing a high gear, perhaps third or fourth gear, this is going to allow us to do a pretty good job of tuning these cells down here under wide open throttle conditions.
It's a fairly narrow focus on our map, though, and it doesn't let us completely fill in the rest of the table, so what are we going to do about that? This is where the idea, or concept, of left foot braking comes in. So what we're really doing here is using the brake system on the car to replicate the load cell, or the power absorber, I should say, on our chassis dyno. So what we're doing is we're using our left foot on the brake pedal while we're driving in order to apply a little bit of braking force through the car's braking system. Now I'm going to demonstrate this here on the dyno and I want you to realize as well that my demonstration here on the dyno is actually even harder than doing this out in the real world and the reason for that is we're only tuning at the moment the rear wheels of the car. The front wheels, obviously, are stationary, and with the way the braking bias works in a car, we generally see somewhere around about 65% to 75% of our braking energy actually directed to the front wheels.
So at the moment that's just wasted. It's doing nothing, so I'm only relying here on the braking effort that's being applied to the rear wheels. When we're out on the road, the front wheels, even in a rear wheel drive car, will obviously help slow the whole vehicle. Okay, so what we've got here is a split camera system where you'll be able to see my feet on the pedals. So what I've done now is I've just taken my left foot off the clutch and I'm just hovering over the clutch pedal, sorry, the brake pedal.
I'm not actually touching it at the moment, and what I'm going to do is I'm going to show you how we can move down this 2,500 RPM column just as accurately, or almost as accurately, as we can by using the dyno. So you can see at the moment we're sitting, I'll just close my throttle down, you can see probably what you want to take note of here during this demonstration is my throttle opening, my throttle percentage. We're sitting at 13.8%. I'll just see if I can close that down very slightly and we'll see if we can get. All right, so we'll just get down to the center of that minus 70 KPA cell and we can see that we're a little bit lean.
We're sitting at about 1.012 Lambda. So I'm just going to add a bit of fuel to that site till I'm onto my target. So at the moment while I'm hovering over the brake pedal. I haven't touched it. Now what I want to do is I want to move into this next cell, minus 65 KPA, and if I would try and do that just by opening the throttle, you can see our RPM increases.
So what I'm going to do, I'm now just applying a very small amount of brake using my left foot. This does take a little bit to get used to. It's a balancing act between how much brake pressure to apply and how much throttle to apply, but you can see that now I'm sitting right in the center of that 65, minus 65 KPA site, and while I'm sitting there I'm just going to tune that cell, too. You can see that we're just a little bit leaner than our target. I've just creeped up a little bit in the RPMs, so I'll just apply a little bit more brake, and we're right in the center of that target.
All right, let's move down, so I'm going to open the throttle further, and this time I'm going to anticipate the additional torque and I'm applying a little bit more brake pressure at the same time. You can see that this time we're a little bit rich so I'm just going to take out just a little bit of fuel there. Let's move down, and we'll come down to minus 50 KPA. Again, this requires a little bit more brake effort. Just get us back on target there.
You can see that I'm moving around a little bit, but for the most part I'm able to stay really stable. It's also important when we're doing this to make very smooth changes to our throttle position. We don't want to be bringing in any transient enrichment that may affect the accuracy of our fuel measurement. So this has come down to minus 30 KPA now and you can see I've obviously already got a bit of a tune in this car, so we're not too far off. Come back down and go to minus 20 KPA.
I'm just going to transition through these sites and you can see. Now I'm holding 100% throttle, wide open throttle. I'm just using my brake pressure. Let's move up to 3,000 RPM. I'll just let off the brakes a little bit.
Come up to 3,000 and I can hold the RPMs steady. So hopefully the demonstration there shows that it is actually really easy to manipulate both the throttle position and the brake pedal, and what you saw there, the control that I had over the car was really just about as good as what we can get with a proper load bearing dyno. I can very accurately move through that row, that column, of cells, and I can tune each one individually. Okay, now let's talk about the things we need to keep in mind if we are going to be performing left foot braking like this. Obviously in order to apply load to the engine, we need to apply the brake pedal, and that's converting the energy into heat, so obviously no big surprise.
That's how brakes work, and the risk here is that we are going to be putting a lot of heat into the braking system, and we need to understand this and we need to be able to manage that. So when we are left foot braking, particularly as we start moving to the higher RPM and higher load areas where the engine is producing more power and more torque, this is going to put more heat into the brake system, and what we need to do is be aware of this, understand it, and manage it. So we may need to spend some time going through doing some tuning using left foot braking and in the end we also need to back off the brakes completely, cruise for a period of time, just allow the car to drive along at a normal road going speed, and to get rid of that excess heat out of the brake system. So some common sense needs to be applied there. If we just simply go about left foot braking and sit there for a sustained period of time, we're obviously going to put an extreme amount of heat into the brakes.
This can be very dangerous. We need to be aware of the fact that if we overheat the brakes we can lose the braking effort from the car. So if at any point in time you start smelling the heat from the brakes, if at any point in time you start feeling the braking energy or braking effort is diminishing in the car, that's a good sign that you need to back off the brakes and allow them to come back down to a normal temperature. Now, there's a thing to keep in mind here as well, when we are cooling the brakes. Obviously it would make sense, or it might seem like it makes sense, to simply pull over to the side of the road, pull into the pits if you're at the racetrack, and sit there for 15 minutes and allow your brakes to cool.
If you have got a lot of heat in your brakes, this is actually the last thing you'd want to do and what it will do is result in localized heating of the brake rotor, particularly where the pads are contacting the brake rotor. This can easily result in your brake rotor warping. So you're actually much better to continue driving the car at a sedate road going speed and allow air flow through the brake system to cool the brakes and bring them back down to a normal operating temperature and it's what I've been doing there while I've just been describing that situation. I've actually left the car there in fourth gear and I've left the wheels turning, despite the fact I'm probably not getting particularly good air flow on the dyno because the car is still stationary. So when we understand the technique of left foot braking it is very easy to actually do a really good job of accessing all of the sites and very, very accurately filling in our fuel table as you've just seen me do, and when we understand this technique we can do just as good a job as we can on the dyno, although we have those advantages, I've already talked about of doing this out in the real world under those normal operating conditions that the car will see.
Now, if you've never done any left foot braking before and you're going to try this, a word of warning here. It's going to feel very, very unnatural. For most drivers, you have been more used to using your left foot either on the driver's foot rest if you're driving an automatic transmission vehicle, or if you're driving a car equipped with a manual transmission, you're more programmed, your brain's more programmed to the kind of effort that's required to press in the clutch pedal, which is quite an aggressive and heavy maneuver. When you're using your left foot on the brake, it requires a lot of finesse and quite a gentle application of force and this does take a little while for you to develop, so particularly when you start left foot braking, it can feel really, really awkward. The car can be erratic.
You can end up with some pretty poor control, but please do stay with it. It doesn't take too long for you to develop the kind of finesse and control that you need in order to do a really good job of your tuning. Okay, so this brings me to the next point of how are we actually going to make these tuning changes? Now, obviously when we're on the dyno we don't need to concentrate on the car or the road. All we really need to look at is the dyno, maybe our laptop screen, and we can take in everything that's happening around us. On the road or racetrack, that's a very different situation and now our primary focus always must be on maintaining control of the car, so it's obviously not particularly safe to be driving along with a laptop on your knee or maybe on the passenger's seat and glancing across to see exactly where you are in the fuel table or ignition table at any particular point.
So there's a couple of ways I tend to deal with this, and one way is to use a helper, and you can use a helper to actually make the changes in the ECU tuning software while you're actually in control of driving the car, or vice versa depending on what's your happiest worth. In this case, what we can do, we don't really need to strictly see the laptop screen. What we've obviously got in front of us on the instrument cluster anyway is our RPM gauge, or our rev counter, and what we can do is simply watch that and we can apply throttle changes and our brake pressure changes to maintain a constant engine speed as we go from essentially close throttle through to a point where we have reached full throttle. Once we've done that at a particular RPM point then we can move forward and do the next one. In this situation, what we're going to be doing is making use of our data logging.
So this is really important if you are road tuning. You're going to be relying very, very heavily on data logging because it can be dangerous to be trying to make these changes live. If you are using a helper then you can sort of develop a bit of a communication technique between the two of you in terms of the person on the laptop keyboard can ask for more or less load until you're central in a cell. It is always very important regardless whether we are on the dyno or on the road, to always try and be as close to the center of your cells when you are making changes. Now, so obviously it's a little bit easier on the dyno, but using that left foot braking technique we can get the same results on the road.
If we aren't central in the cells when we are making changes this can end up with us interpolating with the ECU, interpolating between the surrounding cells and heat's affecting the accuracy of your tuning. So just a quick look here, if we jump back to my laptop software, I did log the tuning while I was talking and presenting that particular test so you can see here, let's just zoom in a little bit, get a slightly finer look at the area we're interested in. So what we've got here is on the top we've got our engine RPM, we've got our throttle position next. We've got manifold pressure, which is the load axis for our fuel table, so that's why that's important, and below this I've got our Lambda target and our Lambda measured so we can see how close to our actual target we are. Now obviously you need to account for the fact that I was making changes to our fuel table while I was doing that demonstration, so hence we can see that our fueling changes quite regularly.
If we are using purely data logging, then we don't need to make any tuning changes while we do one of these tests, and we can simply make our changes from our data logging. So what we can see if we look at our throttle position charts we can see that at the start we're sitting at around about 15% throttle, sorry, 13% throttle I should say, 2,500 RPM. We can see that if I draw a straight line through our RPM, while the RPM does fluctuate a little bit up and down I've done a pretty damn good job of holding that constant using the brake pedal, and what we can see is if we just trace through our throttle position, we can see there I've smoothly and gradually increased our throttle until at the end I've gone all the way to wide open throttle. We've got a nice smooth change in our manifold pressure as we've moved through those cells in the table, and then we can see the errors, if there are any, in our fueling. So what we can do using this technique is we can quite quickly and easily find a particular area we're interested in.
Jump back to our fuel table and the LinkG4Plus software shows us a purple or pink crosshairs which shows us whereabouts we are in the log file, so in this particular instance, we're at 2,500 RPM minus 50 KPA manifold gauge pressure, and you can see while I did correct it live at this particular point, we had a Lambda 0.96, and our target was Lambda one. For all of you who have gone through our practical tuning courses, you'll know that we can correct this once we have got back to the side of the road or the safety of the pits using our correction factor. What we can do there, let's just bring up our calculator and we'll go through that process. What we want to do with the correction that we're going to apply a percentage change to our VE table to correct that error. So what we want to enter in is the air fuel ratio that we're measuring, the air fuel ratio we have, so 0.963, and then we divide this by our desired, or target, so in this case one, so this gives us a result of 0.963.
So what we would do then is we would go back to our fuel table, go to the cell that we're interested in, and we can multiply this by 0.963, and that will correct our error. So it's a very quick way of making our tuning changes based off data logging, rather than trying to manipulate the laptop keyboard while we're actually driving and make these tuning changes live obviously can be dangerous. Now a word of warning, though, a word of caution if you are going to do this, I've already touched on this but it is really, really important here to make sure that our data log is giving us good, solid data, and this is why we want to make very, very smooth and cautious changes to our throttle position. If we're making really sharp erratic changes to our throttle position, we're likely to be encountering transient enrichment, and this is likely to affect the accuracy or reliability of our air fuel ratio data. So it's really important to make sure we're always making smooth changes to our throttle position so that we know that the accuracy of our data is good and we can rely on that information.
The other aspect, I'll just touch on it very briefly here, because it is only specific to the LinkG4Plus or Link range of ECUs. They include a mixture map function, which basically takes data from the log file, the one that we've just created, and by filling in that mixture map, what we can actually see here is how close to our target we were through that particular column of our fuel table. Now the fact that everything there is green is really good. Obviously I was making some changes as we go, but this shows us the amount of error, and we can also directly affect changes to our fuel table straight from our mixture map. Now again, I don't want to focus too much on this because the fundamentals here are applicable to any ECU brand.
If you want to learn more about LinkG4Plus mixture map, please check the mixture map webinar that we do have in our archive. Okay, now, a few more tips. Now, when we are doing this, obviously there's a lot going on and we do need to take care of our brake temperature as we have already discussed. It's generally a slightly slower process than what we could achieve on the dyno, and the reason for this is, or what I generally recommend we do, is that we look at a single slice, or column, of our fuel table at a time. So in this case we've done the 2,500 RPM column.
We'd allow the brakes to cool back down. We'd look at our data logging. We'd make any changes that are required based on our data logging, and then it's also a good idea, obviously, to double check our work. Normally if we're pretty close anyway, we should be able, and obviously if our data is sound, we should be able to get away with only one or maybe two iterations of changes to our fuel table, and we should be dialed in pretty much perfectly. Once we've done that then we can move forward and we can have a look at the next slice, or column, in our fuel table, and just like when we're tuning on the dyno, we're going to use the trends that we see forming, the shape of the VE table that we're forming, and the areas that we have thoroughly tuned, and we can extrapolate those out, copy them ahead into those untuned areas, and this is going to help speed up the process, and it's going to mean that when we move into those untuned areas, we're already going to be very, very close to the money, and that's going to mean we've got less time spent tuning, we're putting less heat into the brakes, and all around we're going to be getting better results.
Okay, so I'm going to move into some questions and answers on this really shortly, so if you do have any questions, please ask those in the chat and Colin will transfer those through to me. In the meantime, if you are interested in learning more about road tuning, obviously in the course of this short webinar we've only been able to touch on a few concepts here. If you are interested in getting a more thorough understanding of how to apply these techniques and how to get the best possible results from your road tuning, then please check out our practical tuning courses, both our practical dyno tuning and our practical reflash tuning course. You'll find it in the courses section on our website. They include an element of how to apply the tuning techniques that we use on the dyno out on the road or the racetrack if we don't have access to the dyno.
So both of our practical tuning courses do include specific modules on road tuning, so that'll give you a full understanding of how to go about what we've just looked at. Now I do want to just reiterate again, when we are tuning on the road, we must make sure that our concentration is primarily on controlling the car. It's always got to be our top priority and this is why we need to be able to rely really heavily on the input from our data logging system so that we can actually look at our tuning results when we're stationary on the side of the road or back in the pits and we can concentrate and focus on the tuning task whereas out on the road we can concentrate on actually driving the car. So particularly if you only have a wideband meter fitted to your dash, it's all but impossible to get the best possible results if we haven't got that connected to our data logger or ECU. We really need to be able to look at the results after the event and see what was happening.
One more aspect that I just want to touch on with the wideband air fuel ratio meter, is generally when I am road tuning, I'm using a portable wideband. The one that I rely on most heavily is the Innovate LM-2 and I use this because it's so easy to move from car to car, and it aligns with the MoTeC PLM that we have fitted to our Mainline dyno, so I know that the results that I saw on the dyno should be exactly the same as what the LM-2 is showing me out on the road. Now what I do is I suction cup that to the windscreen and I can glance at this without really taking my concentration off the road, and particularly how I use this is when I am wide open throttle ramp run tuning, so where I'm doing a full power pull through perhaps first, second, third, fourth gear, obviously and particularly with a powerful car, again I'm concentrating on keeping the car under control at all times, but I can just glance out of my peripheral vision at the wideband meter while I'm doing so and this allows me the opportunity if anything is outside of the realms of where I'm happy with, perhaps my air fuel ratio is too lean, or even if it's too rich, I could simply abort that run and come back to the side of the road, come back to the pits, make the appropriate changes that I need before going out and trying again. There's never a requirement, whether we're on the road or the dyno, to stay in an acceleration pull or a ramp run if the conditions are dangerous and you're not happy with everything. Even with the LM-2 being a portable unit, it is still very easy, with an analog output connector or a serial output connector from that LM-2 wideband meter to connect this to a range of data loggers or ECUs very, very quickly and very, very easily.
In particular, I use this exclusively when I'm tuning using HP tuners. It's very easy to interface the LM-2 wideband meter directly with the HP tuner's interface, and this means that straightaway in the VCM scanner software we have real, accurate air fuel ratio data. Okay, so if you do, if you are interested in learning more, as I said, both of our practical tuning courses do include road tuning demonstrations and road tuning additional modules. Both of those courses are available for 229 US dollars, so you can check those out on our website. Right, we'll move into some questions now.
Coder has asked, "When you're optimizing ignition timing, would it be possible to use a virtual dyno to watch power curves while road tuning? Would you find them as a reliable source for taking power readings with data logs?" Great question, and actually that's something I had intended to discuss, so thank you for bringing that up. Okay, so there is virtual dyno software, and for those of you who aren't familiar with what that actually means, virtual dyno software takes a data log and basically processes it looking at acceleration speeds, so rate of change of RPM, and by inputting some data around the mass of your car, aspects such as guesses towards aerodynamic drag, et cetera, gear ratios, rolling diameter of wheels, the virtual dyno software can produce an estimated dyno plot. Now, there are a lot of enthusiast forums where virtual dyno software is heavily relied on and while I have no doubt that it has got some potential benefits I am cautious about recommending it, and the reason for this is for the virtual dyno software to be useful, it's relying on the conditions of the run being absolutely 100% identical and when we're tuning on the road, it's very, very easy to get anything from minor to large variations in our real world road conditions. What I mean by this is the surface condition of the road, the incline of the road, even the current wind conditions will all have an impact on the results of a virtual dyno output, and while this might get us a result that's perhaps close, when we're trying to optimize the ignition timing and we're looking for changes that may only result in a change of perhaps two or three horsepower at the wheels, I'm inclined to be a little skeptical that the virtual dyno software can provide sufficient repeatability to be truly useful. If any of you out there who are using virtual dyno software have results that differ from mine though, please let us know on the forum.
I'm always interested to hear other tuners' experiences with that software. Barry G’s asked, "What gear is this technique usually performed in, and what about brake fade?" Another point that I probably should have mentioned there with the gear. That's a really good question. So this, really, not too dissimilar to tuning on the dyno becomes a bit of a case of we need to choose a gear suitable to what we're trying to do. Now, particularly if we are tuning a relatively high powered two wheel drive car, and we're performing our tuning in maybe second or even maybe third gear, what this does is it gives a higher torque multiplication of the engine torque through the gear box and in the final drive and this can potentially result in the car wheel spinning.
Ultimately we also have more torque that we're trying to brake against, so that can be problematic. The flip side of this is if we're using a very high gear, perhaps fourth or maybe fifth gear, the torque making its way to the rear wheels is reduced. Our chance of wheel spin, our required brake energy, or effort, is reduced, however, our terminal speed does increase, so it does become a bit of a balancing act, and personally I will generally tend to spend my time tuning in multiple gears depending on what part of the map I'm trying to tune. So I'll generally be tuning in maybe second, third, and a little bit of fourth gear, so it really comes out to the particular application and what sort of terminal speed we deem is acceptable. Obviously if you're on the road you want to be very careful with your current road speed limits.
Currently we've got access to a race track so I am doing most of my road tuning on a race track where I have the benefit of not worrying about oncoming traffic and obviously I don't need to worry about speed limits. Samclose89 has asked, "Can you use a similar process for alpha end tuning instead of speed density? Say ITBs?" Absolutely, and in fact it's a lot easier because here we're directly looking at our throttle position, so basically what I'm trying to do in the speed density system is address my throttle position in order to achieve a specific manifold pressure with alpha n or a throttle position based load input, we're directly trying to achieve a certain throttle position, so it makes it very easy to do. So really the process is exactly the same as what we just looked at and no different at all. RLP01 has asked, "How to be making sure you don't have any transient compensations or accel enrichments when tuning based on your data log and which accel enrichments do you specifically want in there if applicable?" Okay, a really easy way to check that is to actually log your transient, or acceleration enrichment. Certainly that's a function that we can do in the LinkG4Plus software, and that'll allow us to see if any transient enrichments have been invoked.
Generally if we're making really smooth and steady adjustments to our throttle position, this will mean that we're not getting any transient enrichment, and it does become a bit of a balancing act. Obviously transient enrichment is an essential aspect. We need it in there to do the job it's designed for which is to achieve smooth control of our fuel delivery when we do make sharp throttle changes. However, when we are tuning the acceleration enrichment, even when we've got a good transient enrichment calibration which gives us really good control over the air fuel ratio and smooth response to the engine, the important parts we're looking for, it's still very common to actually see small lean or rich areas in our air fuel ratio curve as we go through that transient, and while that's not important for our transient specifically, when we're trying to do steady state tuning like this that can affect our results. Now, particularly, in the LinkG4Plus I really touch briefly on that mixture map function there.
One of the nicest bits of that is that we can filter based on conditions such as transience, so we could, for example, ignore all samples that were the result of rate of change of RPMs above, let's say perhaps 15% or 20% per second, so that really eliminates the potential for transients affecting our results. Henry Latham has asked, "How much does load affect air fuel ratio? Are you tuning fuel maps standing still? How close can you get on a road versus the dyno?" Okay, so the important point to understand here is that we want to make sure that we tune in the same way the engine is going to be used, and this is why I use a combination of both steady state tuning and wide open throttle ramp run tuning, and the reason I do this is we don't tend to drive our cars at let's say 3,000 RPM and wide open throttle, and the reason for that is unless we've got a really heavy trailer on the back and we're heading up a steep hill when we go to wide open throttle at 3,000 RPM, the engine accelerates. It's moving through the rev range. So what I want to do is when I'm at wide open throttle I want to tune the car, tune the engine, the same way the engine will actually be used. So I want to replicate the likely rate of change of RPM or acceleration rate that the engine will be experiencing out on the road or the racetrack.
Now, understandably, we can't be perfect here. The rate of change of RPM in a low gear such as first or second is much higher than fourth, or fifth, or sixth gear but what we're choosing is something that's sensible and replicates how the engine's going to respond under high load. Conversely, when we are in the cruise areas of our maps we are generally out on the road operating in a relatively steady state condition. Our RPM rate of change is minimal, so that's why we're using steady state tuning for filling in those areas of the map. Without trying to overly complicate things here, there is an aspect to be aware of, if you've ever tuned your engine under wide open throttle in steady state, at let's say 3,000 RPM, and you've got your air fuel ratio dialed in absolutely perfectly, but then later on you've performed some ramp runs through that same area, you're quite likely, in most ECUs, to find that your air fuel ratio is now slightly leaner than what you saw under steady state conditions, and again without trying to get too deep into this during today's webinar, this is a result of the fuel film and the way the fuel film inside the engine port is changing based on steady state or transient conditions, so unless the ECU is capable of accurately modeling that fuel film, we are likely to see those errors creep in between steady state and ramp run tuning.
That's why I find it so important to try and tune under the conditions the engine will actually experience. RLP01 said, "Quite a few ECUs have an auto tune algorithm. How reliable are these?" That's a good point. I think it's an aspect that most aftermarket ECUs are now offering and have been for some time. To me, as a professional tuner, I very, very seldom rely on auto tune functions.
I generally find that I can do a better, more accurate job in less time by manually tuning, and also it eliminates any possibility of some strange errors creeping in based on the auto tune algorithm. In particular, for the auto tune algorithms to work, again we're in that situation where we need to make sure that the auto tune algorithm is not being affected by transient conditions and also there's going to be an effect of when we're not operating central in a cell and the ECU is interpolating, depending on how the algorithm treats this condition when we're overlapping cells, that can also affect the accuracy of the auto tune system. So in a nutshell, I wouldn't say that they're a waste of time. Certainly when they're used correctly and you understand how they work, they can be useful, particularly when you're just getting started learning, but it is really important to understand the implications of the auto tune system, and also understand any potential problems that you can create, and if you understand all of that, then yeah, absolutely no problem using them. Dholmes has asked, "Would we find that on the road with fresh air the difference in manifold pressure or oxygen density has increased above what we would normally see on the dyno, hence enabling us to add some additional fuel and extract additional power?" Look, while that is possible, in general I don't see that as a real world problem.
Certainly it's something that you could consider to be a real problem, particularly if you've got an intake system that's designed forward facing and maybe sealed. It may prove that under high speed operation there is a very, very minor RAM effect from the air flow entering the air box that we're not able to replicate or capture on the dyno. In my own personal experience, this really, unless we've got a specific set up to try and take advantage of it, it's really not a consideration that actually affects our tuning in the real world. RLP has also asked, "In the fuel map of the 350Z I noticed that there's some high spots in the maps of these due to harmonics." No, actually, it's due to a very, very badly tuned fuel map. The map that I'm working off for today's webinar is what I actually refer to as my webinar map.
It's not the map that we use when we're out using the car on a racetrack and it's in some places purposely got some errors built into the map. In some places it's just a case of where we have performed some tuning and haven't completed it, so this is just indicative of something that isn't completely tuned. Our poor old 350Z is a bit of a workhorse and it spends a lot of its time sitting on the dyno with a really poorly tuned fuel or ignition map and then we've got our race map which we load into it, if we're going to take it to the track. Dave at Co Motorsports has asked, "Have you used this left foot braking technique on an inertia dyno when you've had no access to a load bearing dyno?" Yes, I have. Not in any great extent though.
I used to do a little bit of tuning remote to where I was and the dyno that I was using was one of the large diameter roller, dyno jet inertia dynos. I did use the left foot braking technique on that dyno with some results that I would call mixed, and the biggest problem I found on the inertia dyno, and we would have seen this here on our load bearing dyno if I'd continued with the demonstration, is again just due to the lack of air flow over the wheels, the lack of air flow over the brakes to try and take that heat back out. You're obviously focusing your cooling fan more specifically on the radiator so we're getting very, very little to no airflow actually passing over the brake system on the car. So left foot braking on an inertia dyno or any type of dyno, is actually worse and harder than doing it out on the road. Also, I'll just touch on there.
You're also on an inertia dyno under those conditions getting zero feedback on torque or power levels. So really you're doing no better than tuning out on the road other than the fact that obviously you're in a safe, secure place and you don't need to worry about the car getting out of control and potentially hurting someone. Sam has kind of touched on the same thing there. He said, "What are the advantages and disadvantages to left foot braking on the road versus an actual dyno?" So again, the same answer that I've just given Dave. Really no advantages.
The only reason I've done it here on our Mainline dyno was it's the easiest way for me to demonstrate the techniques to you guys in the form of a webinar without us having to be out on the road, so that's the only reason I've done it here on the dyno. It's not something I would typically do. Sam has asked, "How do you handle the tuning of AFR during a pull on the road when you cannot look at the gauge and you're unsure of what RPM a lean or rich spot is?" Okay, really good questions there Sam, and a couple of aspects there. First of all, just like when we're tuning on the dyno, I don't go straight to wide open throttle, full power acceleration tests out on the road or the racetrack. I'm going to start building up my map using the steady state tuning techniques and what this does is it means once we actually get to the point where we're starting to do some wide open throttle acceleration tests, our map is already going to be pretty close at least across the first part of our pull and what we can do is then start moving slowly and gradually out into the untuned areas and we can start building up our map as we go.
Now, as I've kind of touched on during the body of the webinar, I really, really strongly advise that you get a wideband meter connected to your ECU or data logger so you can physically data log and see exactly where a rich or lean spot is. I just don't believe you're capable of doing a really accurate job without the benefit of data logging out on the road. However, one thing I will just mention that is worth considering is in a lot of ECUs we have the ability to add a marker to a data log, or alternatively if we just have the ECU looking at a fuel map or an ignition map, often there will be a key, for example, in the LinkG4Plus, the space bar will jump straight to the active cell that the ECU is currently accessing. So a good way of doing this, if I'm tuning on my own on the road or the track, I'll generally have the laptop just sitting on the passenger seat and if I'm worried about anything what I can do is during a pull I can hover over the space bar with my left hand. I'm not looking at the keyboard.
I'm not looking at the laptop. I don't care anything, about anything that's going on on the laptop. I can still hold the steering wheel and I'm concentrating solely on driving the car, but if I see out of my peripheral vision the air fuel ratio move lean, move rich, or I hear knock through my audio headset, I can just tap the space bar. It's instantly going to give me a guide to at least the approximate area on the map where that particular event occurred and I can look at that in more detail. Jeb Colin has asked, "Have you tried the plex knock monitor during a wide open throttle pull on the road? Is it reliable to rely on entirely to tune the timing?" Yes, I have used the plex knock monitor out on the road quite extensively.
Very, very powerful tool, and I do rely on this when I'm on the road or the race track for my tuning. This is really the piece of equipment that I rely on for finding the knock threshold. Would I say I rely on it entirely? No. If I'm on the dyno, I'm still using the feedback from the torque meter on the dyno to let me know where MBT is. Obviously on the road we don't have that benefit.
So yes, on the road I am going to be relying on this to find the knock limit. If we have the benefit of the dyno, then we're using this as just another tool in our sort of arsenal to help us get the best results. All right guys, it looks like it's brought us to the end of our questions. They're some really, really great questions. I know that this is a pretty hot topic.
I hope I've done justice to explaining how I go about doing this. I know that there are a lot of people who are very skeptical about the techniques of road tuning and I really do urge you to not write it off. It's a very, very powerful tool, particularly when used in conjunction with a quality dyno and we are just using our road tuning techniques to optimize the map, or confirm the map that we have achieved on the dyno. This is going to give us the best possible combination and we're going to be able to get the best possible results from our tune. As usual, if you do have any questions that crop up after this webinar has aired, please ask them in the webinar section on our forum, and I'll be happy to answer them there.
Remember, if you do want to learn more about these techniques, please check out our practical tuning courses in the courses section on our website. Thanks guys, I look forward to seeing you all next week.