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Practical Standalone Tuning: Step 7: Steady State Fuel Tuning

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Step 7: Steady State Fuel Tuning

28.06

00:00 - The next step of our tuning process is to complete the steady state tuning of the fuel delivery.
00:05 In this particular instance we're going to tune the table out to 4500 RPM.
00:11 And I'm going to show the process I'm going to be using as well as a few ways we can make changes to the fuel delivery in the Syvecs ECU.
00:20 Because this car is quite loud, what I'm going to do is demonstrate one complete column of our fuel table here.
00:28 We'll tune the 1500 RPM column in its entirety, and then you'll be able to watch me complete the rest of the table out to 4500 RPM.
00:37 Before we do this we'll just go over exactly what we're trying to achieve and the ways we can make tuning changes in the SCal software.
00:46 Let's jump into our software, and what we're going to be doing is tuning this column here so at the moment you can see we've still broadly got those numbers that we set up when we just got the engine up and running.
00:57 Now what we're going to be doing is using the dyno to hold the engine RPM steady, and then by varying our throttle position, we're going to be moving up the table, so we're starting from very light load, very low RPM where we're unlikely to do any damage to the engine, and then we'll gradually build up the load and then following that we'll move onto the next column and build up the RPM.
01:18 What we're going to be using for our tuning here again just like we looked at with our idle tuning in our initial startup, is our fuel multiplier closed loop lambda one.
01:29 So we're looking at what the closed loop fuel control is doing.
01:32 Now at the same time, right beside that we've obviously got our lambda one input but the closed loop trim should be doing its job in order to move us towards our target.
01:42 So what we're really trying to do here is tune the numbers in our fuel table until our closed loop control or our fuel multiplier for closed loop control is sitting as close as we can get it to 1.00 and that means that it's not making any corrections.
01:58 So there are a multitude of ways we can make those changes, let's just come out to a random cell here at 4000 RPM.
02:05 So the first way we can make changes to the cell is simply to directly enter a value.
02:09 So if we enter a value of 3.5 and press enter, that change will then take place.
02:14 Now more likely what we're going to be doing is either adding or subtracting from the cells using the plus and minus keys.
02:24 So if we press the plus key at the moment, you can see we're making a 0.01 millisecond change on the fuel table there.
02:31 Of course we press the minus key and we make the same change in the opposite direction.
02:36 By pressing the O key for our option menu, and C, that will make a coarser change.
02:42 So now instead of 0.01, every time we press the plus or the minus key, we're making a 0.1 millisecond change.
02:48 So very easy to change between coarse and fine using that option menu.
02:52 If we're already on coarse we can press F to go to fine, if we're already on fine, we can press C to go to coarse.
02:59 Now because we are seeing the effect of our closed loop control as well, and this is a percentage adjustment that's being made, we also will want to be able to use the math function.
03:12 So if we press M for math, you'll see we've got a full option list here that we can use.
03:19 So what I'm going to be doing is starting my talking about the multiplier.
03:22 So if we press M again, this will allow us to make a multiplication.
03:26 So for example if we wanted to add 20% to this particular cell we could multiply by 1.20 So that will have the effect of adding 20%.
03:36 Likewise if we wanted to reduce the number in that cell by 10%, we can press M for math, M for multiply again, and this time 0.9 and that will remove 10%.
03:45 Likewise with our math options we can add and subtract, M and A will add, so we can add two milliseconds by pressing M and A, and then we can press M and S and let's reduce that by 2.78 milliseconds, brings us back down to our starting point of three milliseconds.
04:08 So there is no right or wrong way of making tuning changes in the Syvecs ECU.
04:13 Really it's up to the individual.
04:15 And also the magnitude of the change that you want to make.
04:19 Now with that out of the way, let's get our engine up and running.
04:22 We'll get it in fourth gear and we'll get it running at 1500 RPM and we'll start making some tuning changes.
04:29 OK so we're up and running now and we're sitting at 1500 RPM.
04:34 You can see that currently we're just sitting in the 600 millibar cell.
04:38 Now if we try and drop down to the next cell below that, the 400 millibar cell, what we're going to find is that as we reduce our throttle position.
04:48 We're going to find that our engine RPM also begins to drop away.
04:52 So we can't get right into the centre of that 400 millibar cell.
04:56 I'll just try and get as close as we can.
04:58 We come down to about 430 millibar and our RPM's just dropped off a little bit.
05:04 So while we can't get quite into the centre of that cell, we are going to do our best there.
05:08 And we can see that right now the closed loop control is adding around about 7%.
05:13 So what we're going to do is use the math multiplier and we'll add 1.07 and that should get us pretty close.
05:22 Now in this case we are interpolating slightly as well, so that's important to understand.
05:26 We're not smack bang in the middle of that particular cell.
05:30 So I'm going to leave that, we're sitting at 1.00, 1.01 with our multiplier.
05:35 So I'm going to leave that there.
05:36 And we'll come up and we'll get into the middle of our 600 millibar cell.
05:42 And this will be the first cell that we're actually going to be able to get right into the middle of.
05:46 This is always really important to try and get as close to the centre of the cell as we can.
05:50 So right now we can see that our multiplier for our closed loop control is sitting at 1.15 It's adding 15%, 16%.
05:58 So we'll use the math multiplying and set that to 1.16 and you'll see straight away that gets us very very close.
06:07 Our closed loop multipliers drop back down to 1.00 So we can always use the plus and minus key as well to make smaller changes.
06:19 I'll just jump across and make that into a fine adjustment and we'll just add 0.01, 0.02 to just get our closed loop multiplier as close as we can.
06:30 OK so with that cell tuned we can now increase our throttle and come up to the 800 millibar cell.
06:36 However before we do that we can see that we're sitting now at 600 millibar with a value of 2.794 milliseconds.
06:43 Chances are as we increase our throttle and get up to 800 millibars we're going to need to at least be the same if not slightly greater in terms of our injector pulse width.
06:54 So what I'm going to do is just looking broadly at the sort of trend I've got from the two cells I've just tuned, we've gone from 2.56 to 2.79 So what I'm going to do is just guess that the cell here might be close to three milliseconds.
07:10 And we don't have to be absolutely perfect here but it's going to mean that we're not going to be lean as we move into that next cell.
07:17 And we're going to be a lot closer to the mark.
07:20 It will give us less work to do.
07:22 So we'll just bring our throttle opening up a little bit.
07:25 We'll come up to 800 millibars.
07:28 And as you can see that guess was pretty close because our closed loop multiplier is sitting right on 1.0 so that means there's nothing to do here.
07:38 Now I'm gonna follow that same trend.
07:40 And at 1000 millibars I'm going to take a guess that our injector pulse width might want to be about 3.2 milliseconds.
07:48 Again we might be wrong there but let's just see how close we are.
07:53 So again you can see our guess has been pretty close and we're essentially sitting right on the target there, our fuel multiplier for closed loop is sitting at 0.99 So we can just remove a very small amount there using the minus key a couple of times.
08:11 We're right on our target so we can move forward.
08:13 This time I'm going to enter a value of 3.3 milliseconds before I open the throttle further.
08:19 Let's just move up into our 1200 millibar cell.
08:23 OK so we're over to our 1200 millibar cell and again we can see that our closed loop fuel multiplier's sitting very very close to 1.00 I'll just add a very small amount of fuel just to get that onto our target.
08:35 And we can follow our trend again, let's enter a value of 3.45 milliseconds for 1400 millibars.
08:42 And we'll increase our throttle.
08:44 Now at this point I'm at full throttle so we can see our throttle position sensor sitting at 98% there.
08:51 And this is basically as much load as we can apply to our engine there.
08:56 So at the moment we're running it at just on 1200 millibars.
09:00 We can't actually exceed that so what I'm going to do there is just reduce the number in these two cells here a little bit until we're right on our target.
09:10 So let's just come back to idle now and we'll talk about those results that we've just achieved there.
09:17 So what we could see there is we could tune from 400 millibars up to 1200 millibars.
09:23 So it's only a relatively small area of that table.
09:26 This is because we're at such low RPM and we can't produce enough exhaust gas energy to increase the boost pressure past 1200 millibars at that particular point.
09:37 So you've seen me use a couple of techniques there, mainly the math and multiply and then the plus and minus keys.
09:43 We can't quite move on just yet though.
09:45 You'll remember that there was a couple of areas down here that we couldn't get to in particularly the 200 and the 100 millibar zones.
09:53 We can't run the engine in those zones here on the dyno, we're simply not producing enough torque to keep the dyno operating.
10:00 So we don't wanna just leave those as they are though.
10:03 What we can do is again follow the trend that we're seeing here and in rough numbers we've gone from three milliseconds, we've dropped from 200 millibars here and in rough numbers we've got 2.8 milliseconds.
10:16 We're dropping in this case about 0.2 milliseconds per 200 millibars.
10:21 Again we've come from about 2.8 milliseconds down to about 2.6 milliseconds over 200 millibars.
10:27 So I'm simply going to follow that same trend.
10:31 Here we've gone from 400 millibars down to 200.
10:35 I'm gonna leave that value at 2.4 milliseconds, pretty close to another 0.2 millisecond drop.
10:41 In this case we've gone from 200 down to 100 millibars so it's only a 100 millibar drop, so I'm going to set that particular cell there to 2.3 milliseconds.
10:51 Now these numbers that I've just guessed at, they definitely aren't going to be perfect, but this just gives us a pretty good starting point, once we get out on the road when we do actually access those cells, we're likely to be very close.
11:03 Now the other thing I want to do there, is just for the sake of completeness, I'm going to also extend a little bit beyond the area that I was able to tune, again I'll just follow that rough trend.
11:15 So I wanted to set the rest of that 1500 RPM column there to 3.6 milliseconds.
11:20 We're not going to be able to get there, but it's just going to give us something that at least follows the sort of trend that we've seen so far.
11:28 OK so the other thing we've got above us here is our three dimensional graphical view.
11:33 Now it's not really showing us a lot of detail at the moment because of the scaling.
11:37 We can fix that, if we press O for options, and we come down and we press the A key for auto scaling.
11:43 That's going to autoscale our map.
11:45 Now at the moment it looks like a bit of a mess because we're only just broadly getting started.
11:50 But as we start to see more and more of this table being tuned correctly we're going to start to see the shape of the graphical view start to make a little bit more sense.
12:02 OK so what we're going to do now is we're going to also highlight the entire 1500 RPM column.
12:07 We can do that just by holding down the shift and moving around with the arrow keys.
12:12 And I'm going to use the control C function to copy, and we'll just come across to our 1750 RPM column, and by pressing control V, what we'll be able to do is highlight this, control V and we'll copy that across.
12:26 Now this just means that we've copied those existing values that we've just tuned across to our next column of our table.
12:34 Now as we move from 1500 to 1750 RPM, we're likely to see the fuel requirements actually increase.
12:42 We should expect at such low RPM for our engine's volumetric efficiency to increase.
12:47 So before I get started, what I'm going to do is just use the math and multiply function, and what I'lll do is I'll add, in this case we're only moving up 250 RPM, so I'm just going to increase the values there by 4%.
13:00 Now also because I am using quite tight scaling here, quite tight break points.
13:05 When I am tuning, if we go past 1750 RPM, even by 50 RPM, we're going to start interpolating across to this untuned 2000 RPM column here.
13:16 And we've got such tight break points there of only 250 RPM, that's actually going to have a significant effect on our tuning.
13:23 So that we don't have that affect our tuning, what I'm going to do is again highlight the 1750 RPM column that we've just copied and multiplied, and I will move that across to our 2000 RPM column.
13:36 OK so what I'm going to do now is complete the tuning out to 4500 RPM.
13:42 You'll be able to watch that process taking shape.
23:27 So we've completed the tuning of our fuel table there in steady state out to 4500 RPM.
23:32 It is important to note here as well that we have been tuning on our minimum or wastegate pressure level.
23:38 We want to start our steady state tuning at that point, we want the minimum amount of load and stress that we can place on the engine from our turbocharger.
23:47 Now once we've done this as well we can start to see a little bit of a trend in shape turning up in our fuel table.
23:53 And at this point it's a good time to go back and review our fuel table, have a look at our shape, and if there are any unusual points which don't really make sense then we can also go back and reconfirm that those are in fact correct.
24:08 So for example if we see anything like this little area here where as our load is increased we've actually seen one cell which is just dropped away a little bit.
24:18 This would be something that I'd go back and check out.
24:20 Let's just have a look at how we'd progress from here though.
24:23 So what we'll do now is we're just going to copy the values there from our 4500 RPM column and we're just going to basically spread those out through the rest of the table.
24:34 So again at this point I'm expecting that as I go from 4500 to 5000 RPM, I'm going to expect our fuelling may increase slightly so I'm just gonna add 3% there.
24:46 We'll just copy this across to 5500 RPM.
24:50 I might increase another couple of percent there.
24:55 Now it doesn't necessarily have to be perfect.
24:58 Undoubtedly our guesses are going to be inaccurate.
25:02 But all we're doing here is just adding a little bit of shape to our fuel table and taking a little bit of a guess as to the sort of numbers we may likely end up seeing.
25:14 Now at the point we're getting up to 7000 RPM, at this point we would expect our engine's volumetric efficiency to start dropping away so likewise we would expect our fuel table to start dropping away as well.
25:26 So at this point I might remove a couple of precent of fuel and again we're just going to extend that shape out into the rest of our table.
25:35 We'll take out another 4% of fuel at 7500 RPM.
25:41 This by the way is as far as we are going to end up running this engine when we're doing our ramp runs.
25:46 And we'll just continue again, taking another 4% and we'll copy and paste these all the way out to our 9000 RPM break point here.
26:00 And we'll just copy our 8500 RPM column, copy that and paste that across to our 9000 RPM column.
26:09 And we'll make one final change which is to take out a further 4% fuel from that particular column.
26:16 OK so we've got some shape to our table there, we can see we've got a reasonably smooth shape to the fuel table which is essentially what we'd expect here.
26:24 One last thing we do need to do though is we still haven't done any tuning down in the low RPM ranges here.
26:31 We're not going to really be able to load the engine up at 500 or 750 or even perhaps 1000 RPM so what we're going to do instead is copy the shape that we've got from our tuned area.
26:44 So in this case from 1500 RPM.
26:46 And what we're going to do is copy our 1500 RPM column and we're going to paste that into our 1250 RPM column.
26:56 Now remember we do have some zones here that are tuned in our idle areas.
27:02 So in this case around about 2.1 milliseconds and around about 1.9 milliseconds.
27:07 So we want to keep those in mind here as we move down our volumetric efficiency is going to decrease.
27:14 So we're just going to remove a couple of percent fuel from that 1250 RPM column.
27:19 We'll copy and paste that down into our 1000 RPM column.
27:23 And at this point I'm just going to, for the sake of simplicity now and because of these areas, we're not going to really be able to run the car and tune it, this is really the only area we're interested in here is just that the engine will start cleanly and that it will idle cleanly.
27:39 So now what we'll do is we'll just highlight those entire areas there and we're going to just reduce the fuelling, in this case I'm going to set the SCal software to a coarse adjustment and I'm going to bring that back down until we're in the ballpark of where we were idling.