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Practical Standalone Tuning: Step 3: Base Table Configuration

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Step 3: Base Table Configuration

10.30

00:00 - In the next step of our process we're going to begin configuring our base tables ready for startup and this is a process of making sure that first of all, we have sensible numbers in the tables that aren't likely to cause us any trouble and also making sure that our break points for those tables are sensible in terms of spanning the RPM and load ranges that we're expecting to see.
00:21 We're also going to make sure that we have some limits set in place for the likes of our engine RPM and boost just to make sure that if something does go wrong, that we're not going to have problems with the engine being damaged while we're starting our tuning process.
00:36 So let's begin here on our fuel tab so we can see we're already here and we've already got a basic fuel table configured in here.
00:45 So the process here is going to begin by making sure that our RPM and our load zones for manifold pressure are sensible.
00:53 There's a couple of ways we can do this, we can right click and we can use a bin setup wizard so in this case we're on our RPM axis which is our Y axis, we can click in that and it's as simple there as selecting our minimum and maximum values, in this case 800 and 7500 RPM and then the type of interpolation that we are trying to achieve.
01:15 In this case linear.
01:16 We can click OK and the ECU will then generate those break points for us.
01:20 Alternatively what we can do is double click on one of the individual break points and we can adjust that to suit our own requirements and press enter and that will be locked in.
01:32 So the break points that you want to use will be very specific to your application.
01:37 Again the tendency as we talked about in the main body of the course is to use too many break points and this simply makes more work than we need.
01:44 Generally a good rule of thumb here is to have our RPM set up every 500 RPM, maybe with a little bit more detail down around our idle area and then we also want to use break points for our manifold pressure of around about 20 kPa give or take.
02:01 In this case we can see that we've spanned out to 250 kPa.
02:05 And that's going to be ample given that this is about as much boost pressure as we are expecting to run.
02:11 It's important to mention that the ECU will interpolate which is why we don't need excessive numbers of break points.
02:18 What I mean by this is if the ECU is operating between two RPM zones, it will be interpolating between the surrounding cells.
02:26 Likewise if we do happen to exceed the break points on a particular table, it's not like the ECU just stops producing fuel or ignition.
02:35 The numbers will be extrapolated that are in the existing table out into those areas off the end of the table, still good practice to make sure that our table does span the range that we are expecting.
02:46 The other thing to point out here is as I was making those changes, we can see that the ECU has actually interpolated so we can see this row in here that has changed and now is in solid black.
02:58 So two things there, showing that these numbers are not flashed into the ECU, so they're not permanent and also that the ECU has interpolated those changes required as I've changed that break point.
03:10 So what we can do that is flash that in, that'll make those changes permanent..
03:14 Now with our fuel table, given that this is a VE based fuel model we can start here by simply setting the entire table to a fixed value for simplicity, I'm going to do that by highlighting the entire table here.
03:28 And we should be able to get our engine up and running if we just enter a value of let's say 50%, somewhere in that region should be close enough to get us up and running and that's definitely not going to be perfect but that's where we're going to be fine tuning this as we go through the tuning process again, I'll just make those changes permanent.
03:46 So we've got our main fuel table configured here with some rough numbers however there's a little bit more work to do here.
03:53 What we're going to do is come across to our fuelling, we'll come down to our fuel tables here and we can see we've got our VE table one which is what we're looking at now but this also works in conjunction with our lambda target table.
04:06 So we'll bring that up here and we'll just expand that so we can see it in a little bit more detail.
04:12 So this is our air/fuel ratio or lambda targets, the desired lambda values that we want the engine to be running.
04:19 And the idea here is that we need to set these to our desired targets and then we're going to be tuning the VE table until we achieve that.
04:26 And these two values will be displayed here in our little bar graph which makes our tuning nice and easy, we can just adjust our VE table until we're on our target.
04:35 I've already gone ahead and set this up broadly, the specific air/fuel ratio or lambda targets that you choose to use will depend on your engine, your application and these aren't set in stone, we can of course modify these as we see fit once we get up and running.
04:49 We can see here I've spanned out to 200 kPa or 100 kPa of positive pressure on our load axis.
04:56 Remembering again that the numbers that we have here, 0.78 will actually be extrapolated out as we increase our boost pressure.
05:03 So that's probably going to be at least where I want to get started and again we've got the RPM axis spanning the range of RPM that we're likely to see.
05:13 It's not so important with our target lambda table to have really high numbers of break points because we don't tend to vary our lambda target that specifically.
05:24 We can also see here that we've got this shown graphically.
05:27 Just as a point because we haven't touched on that yet, we can define how the table will be shown here.
05:34 Click on the left icon here, this will just show the grid of numbers.
05:37 If we click on our 3D graph only that will show the 3D graph, come back here, we can also split, horizontally or vertically as we've seen there, that will just give you a graphical display of the numbers so it makes a little bit more sense.
05:50 So we've got numbers in here for our lambda targets that are at least a good place to start, so we can close that down, we're now going to move over to our ignition and we're going to do exactly the same thing here.
06:02 Again everything that we've just learned for our break points is exactly the same, we can actually see that those break points get carried across between the two tables.
06:12 It's normally a good idea to make sure that your break points between an ignition and a fuel table match anyway so you are working in the same zones.
06:18 While we've already got numbers in this table here, what we're going to do just to safeguard ourselves while we're getting started, we'll highlight that entire table and we'll start by setting the entire table to 15° and I'll mention we can do an across the board change like that just by entering the value, 15 in this case, pressing enter and that will lock in that change.
06:38 What I'm going to do though is be a little bit more conservative than this actually, we're going to highlight the entire operating area above about 150 kPa or 50 kPa of boost here, we'll set that to 10° and depending on the compression ratio and the boost pressure, we may want to even be a little bit more conservative again up in these higher boost areas, just about giving us some conservative values while we're getting ourselves up and running so that there's not going to be any chance of doing damage to our engine.
07:05 With those changes made we can then make those permanent into the ECU.
07:10 While we're making our base table configuration changes, this is also a good time to just ensure that we've got some sensible limiters set up.
07:17 We've already touched on these briefly but let's head across to our fuel tab here and we'll bring some of these up.
07:23 So we'll start here under our fuelling menu with our fuel cut.
07:27 So we can see here we've got our rev limit cut here set at 7500 RPM so this will cut fuel at 7500 RPM, safeguarding and protecting our engine.
07:38 This actually also works in conjunction with under our ignition, we can see that we have a soft rev limiter as well, we can bring that up, so obviously one works via fuel cutting, the other works via ignition cutting, we can choose whether or not we will enable the soft cut, in this case we can see we've got this set up at 7400 RPM with a 100 RPM control range.
08:01 We'll close that down and we've also got our boost cut here which is fuel cut above pressure, in this case set to 300 kPa.
08:09 That's probably a little bit optimistic, two bar of boost here, so we can drop that down a little bit.
08:15 I'm going to be aiming to run 250 kPa so let's start with that set at 260, we'll be able to come back and address that at a later point.
08:23 While the boost cut that we've just set up is definitely going to be effective, in some situations this may not be the best way of dealing with an over boost cut.
08:31 For example if we are targeting a variable boost curve relative to RPM we may find that for example at high RPM, where we've tapered our boost targets down, remaining with our boost cut set at 260 kPa could result in excessive boost pressure at that RPM point.
08:50 So there is an alternative where we can set our boost cut relative to our boost target.
08:54 Let's just move down through our menu structure and we'll have a look at that.
08:58 We can find that under our engine protection.
09:01 So we'll open up the engine protection here and what we want to do is come down to our overboost protection option, let's double click on that and we'll bring that up.
09:09 We can see that this is currently disabled, we can enable it simply by clicking the little tick box there.
09:15 And now what this will do is add a margin, it's adjustable but in this case by default there's 20 kPa above and beyond our boost target so this will always give us a 20 kPa buffer above our boost target relative to RPM so just an alternative way of creating that boost cut safety.
09:33 Now it is also worth mentioning here that if you are going to be tuning a turbocharged engine then it's always a sensible place to start with the wastegates set to zero duty cycle and run the engine on the minimum boost pressure that we can achieve.
09:47 On this particular engine, that's around about 15 psi, around about 200 kPa and what we may want to do there is start with our boost cut set just a little bit above this range just to make sure that if there are problems with our boost control plumbing or our wastegate operation, that we're not going to end up damaging the engine, before we end up getting to our existing 260 kPa cut.
10:10 There's a personal decision there based on your own comfort zones and the engine you're tuning.