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Practical Standalone Tuning: Step 7: Steady State Fuel Tuning

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Step 7: Steady State Fuel Tuning

32.38

00:00 - Now that we've got our engine running, we've got our engine idling, and we're confident that mechanically the engine is sound, it's time to begin some actual tuning.
00:10 And we're going to start this initially with just the fuel tuning, and we're going to be looking at how we can use the dyno to help us tune the fuel in steady state.
00:21 And along the way, we're going to look at the various ways that we can make adjustments to the numbers in the fuel table, or VE table, in the Infinity ECU.
00:31 This is a point that's worth discussing that isn't necessarily a right or a wrong way of making these adjustments.
00:40 There are various methods that we will look at, and what method you use, will depend a little bit on how comfortable you are with tuning, how familiar you are with the software, and also, often, the magnitude of the correction that you need to make.
00:58 So now that we've got our engine idling, you can see I've made some further adjustments to our idle cells here.
01:05 Just now that the engine is up to a normal operating temperature, you can see we've got a coolant temp of 86 degrees centigrade and an air temp of 29.
01:15 The two pieces of information we're going to be looking at to help us with our tuning here is our Lambda1, which is if your ratio input and our Lambda Target which you will remember comes from our Lambda Target Table.
01:30 The process we're going to go through here, what we're going to do is use the dyno to control the engine up here.
01:37 So the dyno's going to apply a load that's going to keep the engine rpm or actually, more correctly, the roadspeed consistent.
01:47 And it's going to let us move up and down these columns tuning each cell individually.
01:54 Now we always want to start with the be at minimum amount of load and rpm on board, and then build up from there.
02:02 And the reason for that is I'm likely to do any damage to the engine with this very very little load on the engine.
02:11 So, while we're getting a bit of a picture of the shape of the fuel curve and later on the ignition curve, we want to start from low load and low rpm and build up from there.
02:22 And what this means is we're going to see the shape or trend of the fuel table, VE table, developing, we're going to be able to fast track out tuning, by copying that out into the untuned areas.
02:34 And this is going to mean that before we get to those areas, we're already going to be a little bit closer.
02:41 And what we're going to do is start here at 1000 rpm on the dyno.
02:46 And I'm just going to get the engine running at fourth gear in order to do this.
02:50 And what you may need to do when you're getting the engine running at these very early stages, is make some adjustments in these untuned areas.
03:00 You can see, particularly now, we're sitting at 1.3 Lambda and 1500 rpm.
03:08 Now I'm just going to bring the engine rpm down by using the controls on the dyno, so we can get down to 1000 rpm target.
03:18 Now, this is a good indicator as well of just how easily we can make these tuning changes to the fuel delivery.
03:27 You can see at the moment, we're sitting at 1.3 Lambda, and very very lean if you notice no doubt about that.
03:34 But given the modest amount of load, so if I at the moment I've got 9.5 percent throttle opening, so little load on the engine.
03:42 The engine's not going to be damaged by that lean if you're rush.
03:46 So what we want to do now, we're at a 1000 rpm, is just close the throttle down and see how far down in the load we can get.
03:55 Now, there is a limit to how far we can go, and you'll see right now what's happened, I've closed the throttle further, and now the rpm has actually dropped.
04:06 Now this is because it takes a certain amount of engine torque to just simply drive the dyno.
04:12 So if we close the throttle down, the engine torque reduces, and at some point, there's not enough inertia to drive the dyno, and the dyno will simply slow down.
04:20 What this indicates is the lowest point in our table that we can comfortably reach.
04:26 You can see at this point, we're sitting at 40 kPa.
04:29 So this 40 kPa zone is about the lowest load point we can get to.
04:34 Now we're going to make some tuning changes and you can see our Lambda is 1.14. 1,16 at the moment, and our target is 1.0.
04:45 So let's have a look at how we can make some changes.
04:48 And the first way I'm going to make this change is simply by entering another number into the table.
04:55 So let's guess a value of 60 percent.
04:59 And you can see that when I enter 60 percent, our measured Lambda is now much closer to our target.
05:05 It's still a little bit out, we're sitting at about 1.02, no it's actually pretty good.
05:12 One key when we are making these adjustments is to make sure that before we make an adjustment to the cell we're tuning, that we are truly operating in the middle of that cell.
05:23 And this is much more important as well when we're first developing the fuel table because we can end up with quite large changes from one cell to the next.
05:32 So you can see that my engine rpm is 1000 and teen, 1000 and 15, so we're very close to our 1000 rpm target.
05:40 And the manifold air pressure is 40 kPa.
05:43 So we are central in this particular site.
05:47 See, if we aren't 100 percent central in the site, the ECU won't be able to apply there for most surrounding cells and that can effect the result.
05:58 So we actually are still probably about one percent too lean there.
06:02 So let's take another guess and I'm going to enter a value of 61 percent, and we'll now a little bit too rich.
06:11 So, we're very very close.
06:12 Let's try 60.5.
06:15 And we're right on our target.
06:17 So this method of directly entering numbers and basically guessing at what the value might want to be I call this the trial and error method.
06:26 And there's nothing strictly wrong with it.
06:27 This is probably the method that 90 percent of tuners use.
06:31 However, there's much faster ways to very quickly dial in our fuel delivery and get it closer to our target.
06:38 So we're going to have a look at some other options.
06:41 So once we've tuned this particular cell, what we want to do is now increase the throttle opening, and move up to the next load zone, which in this case, is our 60 kPa site.
06:53 So I'm gonna move the cursor up here and I'm just going to open the throttle slightly but before I do that, one thing that will help as you move through this untuned VE table is you can see we now have values of 54, 61, 60.5.
07:11 As we move up, our next untuned site still has 50 percent in it.
07:17 And we could reasonably expect that as we open the throttle further, the air flow into the engine will increase, hence the volumetric efficiency will increase, and it's likely that as we move up the load zones, that the VE numbers will smoothly increase.
07:34 So what I can do is take a bit of a guess at what this value might be at 60 kPa, before I get there.
07:41 Chances are it's going to be at least 60.5, if not more.
07:46 So what I can do is just copy my value from the tune zone, up until the 60 kPa row, so we're already closer by the time we get there.
07:55 So now let's bring the manifold pressure up to 60 kPa, and we'll see what if your ratio is.
08:04 And you can see that we are still quite a lot leaner than our target.
08:08 We're sitting at 1.15, 1.16.
08:14 So, we want to increase our VE number further.
08:19 So let's just get back into the center of the site.
08:22 And we're going to look at some other ways that we can make tuning changes to the cell that are a little bit quicker.
08:28 So what we can do is use the correction factor that we looked at in our Tuning Fundamentals course.
08:36 When we take our measure of our ratio Lambda, divide that by our target, and we use that as a correction factor.
08:44 So let's do that now.
08:45 We'll just get back down to 60 kPa exactly.
08:48 And what I'm going to do is bring up our calculator function.
08:53 We'll just move that out of the way so we can see.
08:55 So you can see that at 60 kPa, we're sitting at right about 1.12 Lambda.
09:04 So let's enter 1.12, 1.12, and then we want to divide that by our target, which in this case you can see is Lambda 1.
09:16 It gives us a correction of 1.12, or 12 percent.
09:19 So we need to add 12 percent to that particular zone in order to correct the error.
09:26 So we can still use that calculator to do that.
09:28 If we use the multiplication function, and multiply it by the current VE number, 60.5, it gives us a value of 67.7 or 67.8.
09:40 So we can enter 67.8 into our table, and straight away, if I get back down to 60 kPa, you can see that now we are exactly on our target.
09:55 This is a much quicker way than the trial and error method, which generally only needs to make one adjustment, and if that adjustment doesn't work perfectly, we're likely to be within a couple of percent, and we can easily correct that by adding or subtracting to the numbers in the cells.
10:11 So let's go further.
10:12 We're going to increase our throttle again before we move up to 80 kPa.
10:16 I'm going to guess at the value that we might need to see in this 80 kPa site.
10:22 A bit of a hint here as well as to look at the general trend see? You can see we've gone from 60 to 68 percent essentially.
10:30 So we might reasonably expect that moving up another 20 kPa, we might need to add about another 8 percent.
10:38 So before we move forward, let's see it.
10:41 This particular site at 74 is a bit of a guess as to what it might want to be.
10:46 So now we're going to increase our throttle opening, and move up to 80 kPa, and while I'm doing this, with a rolling road dyno, as we make adjustments to our load, we will see the rpm tend to creep a little bit.
11:05 As we apply more load, what's happening is the tires are deforming, the car will move forward onto the roller.
11:11 So if we are holding 1000 rpm at very light throttle, it's likely that if we don't adjust the point on the dyno, that when we got to wide-open throttle, the rpm will flare up a little bit.
11:24 So I'm constantly making these adjustments at the same time.
11:27 Okay so now we've moved up to our 80 kPa zone, and you can see now, we're a little bit richer than our target.
11:34 We're sitting at around about 0.9, 0.91, and our target's 0.93.
11:41 So we've looked at how to use the calculator.
11:43 But when we're using units of Lambda, we don't really need the calculator function.
11:48 It's obviously pretty time consuming.
11:50 So I can look at this, and I know that at 80 kPa we are seeing 0.90 and our target's 0.93.
12:00 Well in this case, we're actually 0.88.
12:03 So we know that we're at about four, maybe five percent, too rich.
12:09 So what we're doing there is looking at the difference between our target and our measured Lambda.
12:14 So in this case, about 0.4 difference, which is four percent.
12:19 What we can do is simply take four percent straight out of that cell in the table.
12:24 And there's a few ways we can do this as well.
12:27 If we use the plus and minus keys, these will make one percent changes to our VE.
12:32 So if I press the minus key four times, that's taken four percent out of that particular cell.
12:39 And you can see now our Lambda is sitting, when I get back down to 80 kPa, our Lambda is sitting perfectly on our target.
12:49 Now, another way we could do that, let's just go back to our original value, we can also use math functions in the AEM Infinity.
12:57 So press the z key, and then we enter the multiplication symbol.
13:02 This will make it multiplication.
13:05 So we want it to take four percent out of the value.
13:09 So to do that, we enter a value of 0.96.
13:14 So the 0.96 will remove four percent fuel.
13:18 And again you can see that that's got us straight onto our target very very quickly.
13:24 So we can choose to directly enter numbers, we can choose to use the plus and minus keys to make changes.
13:32 If we need to make a courser adjustment, we can use the control and plus and minus keys to make ten percent adjustments, or we can also add and subtract or multiply using the math functions.
13:45 Alright let's continue now.
13:47 So we're going to up to our 100 kPa zone, and again we're looking at the difference there.
13:53 We're going from 68 to 71.
13:55 So we've added three percent.
13:57 So I'm going to do the same in our 100 kPa zone.
14:01 I'm going to add 74, so we're just again taking a guess at what this value is going to be.
14:09 And let's go to wide-open throttle, and see how close we are.
14:16 Then you can see again, we're a little bit richer.
14:19 This time I'm just going to remove a little bit from the VE table, using the minus key.
14:24 So I just hit that three times to remove three percent, and we're pretty well right on our target.
14:32 Okay, now that's got us our current 1000 rpm column of the fuel table tuned, or the VE table tuned.
14:43 There's a few things that I want to talk about before we carry on.
14:46 First of all, we can't tune as we saw, we can't tune down below around about 40 kPa.
14:54 Now what this means is we've got a section of fuel table or VE table that we can't access when we're on the dyno, because if we close the throttle, we're simply going to have the engine rpm slow down.
15:07 Now, that doesn't mean we want to leave these zones untuned.
15:10 And again, we're going to take a bit of a guess as to what these VE numbers are likely to want to be.
15:18 Now what we have done is we've tuned our thirty kPa zone here and we've done that because this is about where the engine idles, and what I'm going to do now, we've actually got everything up to a proper temperature, I'm just going to reduce the numbers in our idle area there just to get us down to our target Lambda.
15:39 And generally when we're first starting to tune the engine, we will need to make some adjustments like you see me make there, while we get started.
15:50 Okay we haven't bee able to tune this 35 kPa zone, so what I'm going to do is simply make a guess by interpolating between the 40 kPa zone that we've tuned at the load and the 30 kPa zone which we've tuned at idle.
16:05 And what we can do, if we right click on the table, we're going to get a list of commands we can use.
16:11 And what we want to use is the interpolate vertically option.
16:15 And we can access this by using the V key.
16:18 But if you forget the shortcut keys, you van always right-click.
16:21 So that's going to give us a value in between.
16:24 And now we can see we've got the smooth shape to our table forming.
16:30 And you can see that that's represented graphically over here.
16:33 A little hard to see when we've only got only one slice of this table tuned.
16:37 And what this means though is I'm going to also extrapolate that same sort of trend down until the lower zones, below where we can tune.
16:46 In this case, you can see that we've essentially gone from 55 to 49 percent, so we've removed six percent.
16:54 So what we want to do is probably removed a similar amount of fuel as we move down into these untuned zones.
17:01 Instead of removing six percent, I'm actually going to remove four percent, and the reason for that is, chances are, we're going to be perhaps a little bit rich and it's always better to be a little rich than a little lean.
17:15 So let's remove five percent now, and we will sit this, Sorry I'm going to remove four percent actually, let's set this zone to 45 percent, and we're going to do exactly the same as we move down to the zero kPa zone.
17:30 And there's time.
17:31 I'm going to remove another four percent, and set it to 41.
17:34 Now, these areas we will be addressing when we get the car out on the road to complete the tune.
17:41 But this is going to hit us, taking the guesses and extrapolating that shape of the fuel curve or the VE curve, is likely going to have us a lot closer when we actually reach those zones.
17:52 So it's always important to unerstand that the general shape of the engine's VE curve should be relatively consistent and smooth.
18:00 It isn't always, but if we can't get into these areas, that's what I'm going to do, I'm going to guess that the shape will follow that same trend.
18:11 Okay, so now we can move up to our 1250 rpm zone, and before we do that, to speed up the process, I'm going to highlight the 1000 rpm column.
18:21 I'm going to use the copy function, which is Control and C, and then I'm going to paste that into the 1250 rpm column.
18:32 And the reason for that is as we move up in the rpm, we can reasonably expect our VE to increase, or our airflow to increase.
18:40 So the chances are that the numbers in our 1250 column should probably be at least what we saw at 1000 rpm, if not higher.
18:50 I'm going to go one step further, and I'm going to highlight that column again.
18:54 I'm going to use the Z function to use a math function, and I'm going to multiply that column by 1.05.
19:03 So this adds five percent fuel.
19:06 This means that once we get started in that column, we should already be close to our Lambda target.
19:13 So let's get our engine running again, and we will increase the rpm on the dyno, and we will have a look at how the Lambda looks as we move up in our rpm.
19:26 So I'm just increasing the rpm on the dyno, and you can see that that worked pretty well, straight away as soon as I move into this column.
19:39 You can see that we're already very close to the Lambda target, probably if anything, a little bit lean.
19:46 So what I'm going to do before I make individual cell changes, what I tend to do, is make an overall adjustment while the entire column is highlighted.
19:56 And the reason I do this is because if one particular cell is a little rich or a little lean, the chances are that the entire column is probably going to follow that same trend.
20:08 So, let's just now we've made an overall adjustment, I'll just get down to our 40 kPa zone, and when we're actually in the middle of the zone, you can see we are a little bit rich.
20:22 So you know I'm just going to highlight that column and make that overall change, my first change is always going to be to the entire column.
20:30 So I've got the 40 kPa tuned correctly now.
20:33 I'm going to increase the throttle opening.
20:35 We'll move it up to 60 kPa, and we'll see how close we are there.
20:43 Okay, so we get to 60 kPa, you can see, again we're very very close.
20:47 We're three percent lean.
20:49 So I'm just going to hit the plus key three times to add three percent fuel, and straight away, you can see we're on our target.
20:56 Now another trick that we can use with the Infinity, as well which can help speed up our process, if you look down at the bottom of our script here, you can see this function here which says NewVE.
21:07 So the Infinity is constantly calculating what the actual VE in the particular cell where axis sync should be, based on our measured Lambda and our target.
21:19 So we can use this value here to enter straight into the cell if we wish, it's another way of speeding up the tuning process and the Infinity helps us out there by guessing what the VE should be based on the Lambda error, since it's automatically doing the calculation that we looked at.
21:36 Okay let's move up to our idkPa site now, and you can see as soon as we move into the idkPa site, again we're already very very close, if anything, we're about two percent lean.
21:52 So I'm just going to use the plus key and add two percent to our idkPa zone.
22:02 And you can easily make small adjustments up and down as you see fit using those keys, once we're very very close.
22:09 So now we're going to go to wide-open throttle and we're going to look at the 100 kPa site, and just get our rpm right on our target.
22:26 And again, straight away you can say that we're absolutely, perfectly on our target.
22:31 So this is the benefit of copying our tuning here and getting an idea of what the shape of that curve should be.
22:40 And this speeds it up because we're not starting from scratch, we're starting from a blank table every time we move into an untuned area.
22:49 So I'm going to complete the process now.
22:52 We're going to go through and tune out to about two-thirds of engine.
22:58 So in this case, I'm going to tune a steady state out to about 4500 rpm, so you can watch that process being completed.
23:05 Before I do that, one other thing I will mention, if we are tuning an engine, particularly a powerful one, particularly perhaps one that's turbo-charged, if we move up in the load, and we find that as we move into an untuned site, our Lambda is lean, particularly if it's very lean, rather than sit there under a high-sustained load and make changes to the VE number, what I would tend to do is back the throttle off, reduce the load, get back into a tune zone, where our Lambda is on target, and then make it a change to the cell that was lean, and then go back into that cell and see if we've corrected it.
23:43 It's always better to start with the air fuel ratio, richer than we like, and lean it out, rather than start too late and try adding fuel.
23:51 Okay so I'm going to complete the restable table now so that you can watch the process.
29:44 Alright, so we've gone through and we've tuned the VE table out to 4500 rpm.
29:50 Generally, what we're expecting to see with this, most engines would be smooth, and consistent shaped to our VE table.
29:59 And you can see we haven't quite achieved that here, we do have some areas where the shape of the VE table isn't 100 percent smooth.
30:08 And we can't expect to see that particularly on some naturally, as provided the engines and those with large cams in particular, where we will see some areas where the VE changes rapidy across quite a short rpm range.
30:24 Now that we've done that process, we're not quite finished.
30:27 What I' going to do before we carry on is just going to copy the 4500 rpm column and I'm going to pace that our through the rest of the table.
30:40 Now, what that's going to mean, is that when we start doing wide-open throttle runs, we're already going to again hopefully be close to the correct VE before we get there.
30:55 And what I might also do at the same time is take a little bit of a guess as to what the VE table might continue to do as we move past those areas that we've tuned.
31:06 Remember that we always want to be ideally starting a little bit rich and then move a little bit leaner, we'll move some VE from the table to get to our target.
31:19 So what I've done here is I've just simply increased the VE tables into those untuned areas and we can address those once we get started with that tuning.
31:31 Before we move on, there's one last area that we want to address.
31:34 You can say we haven't done anything without 500 and 750 rpms on us.
31:40 We can't tune those on the dyno, we can't get to them, however, it's fair to assume that the shape of the table will be consistent in those areas.
31:51 And what we can do is copy our 1000 rpm column into those untuned areas.
31:58 Again, what we could do if we wish is take a bit of a guess based on the shape of the VE table, and reduce the efficiency slightly in those untuned areas because at lower rpm, we would expect the efficiency to decrease.
32:13 What we do want to do when we're making these changes is make sure that in our idle areas, that our VE numbers are still consistent, and you can see, we're still sitting on our target of Lambda1.
32:26 So it takes us through tuning of steady-state fuel.