Practical Standalone Tuning: Step 3: Base Table Configuration
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Step 3: Base Table Configuration
18.33
| 00:00 | - The next step of our 10 step process is our base table configuration. |
| 00:03 | So the intention here is to get some numbers into our fuel and ignition tables, plus a few additional tables that we're going to be relying on that'll at least be in the ballpark so when it comes time to get the car up and running, we should be at least close enough to make the engine run. |
| 00:20 | These aren't by any stretch of the imagination going to be the final values and as we'll see it's going to be really easy to manipulate these tables as and when we see fit once we actually get stuck into the tuning so this is a very broad high level setup here and we don't need to be too fussy about the specifics of the table setup. |
| 00:38 | Again there'll be plenty of time for adjusting these to suit when we get further into our actual tuning and we've got the engine up and running. |
| 00:45 | So let's dive back into our tuning software and for a start what I'm going to do is press the F key to get us back to our fuel table. |
| 00:53 | So what we're going to do is start by considering our break points here. |
| 00:56 | Everything's actually looking resonably good in this default map. |
| 01:00 | The engine revs to 8000 RPM so we do have a break point right out at 8000 here. |
| 01:05 | Generally, particularly with stock heads, cams, and a factory turbocharger, there's actually little to no benefit running it out that far so normally I'd go 500 RPM past our maximum RPM but in this case 8000 RPM is probably pretty close. |
| 01:22 | So what we can do here is we can press the X key, that'll bring up our axis setup. |
| 01:27 | An alternative way of doing that, if we right click, and this is a good one to keep in mind, if we right click on the table we will see all of these options which gives us our axis setup which is right here but also there's a wide range of ways that we can manipulate the numbers inside of the table as well so let's come back up to our axis setup here. |
| 01:47 | And as I mentioned, our break points for our engine speed are probably OK. |
| 01:51 | We can see that we already have a break point here at 750 RPM. |
| 01:55 | I may want to add one in maybe at 1250 just to help with our transition away from idle. |
| 02:01 | Normally I'd probably have this engine idling at maybe 950 to 1000 RPM so 1250 gives us a bit of a break point there just to transition and get really nice control of that transition from idle to moving but again not really too fussed at this stage, very easy to add if we want to, we can simply click on the plus button right here and we'll do that and it'll ask us where we want to enter that break point, let's try 1250 there, that'll do exactly that, Likewise if you want to get rid of it, press the X key, back to where we started. |
| 02:31 | Let's have a look at our manifold gauge pressure axis. |
| 02:34 | So first of all let's talk about the manifold gauge pressure, what that channel actually is and this is just the difference between our manifold pressure and the current barometric pressure, as measured by the onboard sensor. |
| 02:46 | You can set this to manifold absolute pressure if you would prefer but I will leave it at manifold gauge pressure at the moment. |
| 02:52 | So what we've got here is our base values and probably for the most part, this is just fine. |
| 02:59 | We are looking at 20 kPa increments, except for at this point here, we've got one at 60, one at -55 and one at -50 which is probably a little bit closer in breakpoints than we need. |
| 03:12 | Generally 20 to 25 kPa is just fine. |
| 03:17 | What we might find is that it's beneficial to add another break point in terms of load, around about where the engine is naturally idling. |
| 03:25 | We can find that out later on, not a problem. |
| 03:27 | Also can be beneficial to add another break point just to give us finer control around the sort of manifold vacuum that we see at cruise conditions but again for the most part, pretty happy with what we've got there. |
| 03:38 | Remembering that more break points is simply going to end up making more work for ourselves so there's no point having more than we need. |
| 03:45 | Let's just scroll down to the bottom here and we can see that our maximum break point here, got 140 and 160 kPa so if you prefer to work in imperial units, about 20 psi and about 23, 24 psi. |
| 04:00 | As I mentioned, we're probably going to be running around about 20 psi maximum so we've just gone a little bit above and beyond that so that's absolutely fine. |
| 04:07 | So turns out in this case, the base configuration, I'm pretty happy with that. |
| 04:11 | When we click OK, it'll ask us if we want to interpolate. |
| 04:14 | Remembering I just removed one cell so we'll click yes and basically for all intents and purposes now, nothing has changed. |
| 04:21 | So let's have a look at the values in this fuel table, again this is just our base values here. |
| 04:26 | We can take a bit of a stab in the dark here at what sort of numbers we may want to get the engine up and running. |
| 04:32 | So what I'm going to do is click in that top left corner here. |
| 04:34 | That's going to have the effect of making a across the board change to the entire table. |
| 04:39 | Now generally somewhere, if we're dealing with a VE based fuel system, somewhere around about a 50% value would be enough to get us up and running. |
| 04:47 | The engine might not run nicely but it should be able to run. |
| 04:51 | With injection time based, it's a little less cut and dry because we do have that master injector pulse width value as well that comes into this calculation. |
| 05:00 | What I'm going to do here, just looking at this as a base table, and we see that in the idle areas here, we've got values around about 25% and because it's a base table, base configuration, probably that should be about right, maybe there or there abouts. |
| 05:19 | So probably don't need to be 50 but let's just set the whole table for the moment to a value of 40%. |
| 05:24 | It might not be right but doesn't matter as you'll see, very easy to correct that once we get a little bit further into this. |
| 05:30 | So at this point we've got our fuel table basically configured, we've got a base number in there that should be enough to get us up and running so let's move on, we'll press the i key and we'll have a look at the ignition table. |
| 05:42 | Now essentially everything's exactly the same here, again I don't really see a lot of need to go and make broad changes here, we've got the same range of spanning. |
| 05:54 | You will notice that this time we are using manifold absolute pressure for the load axis instead of manifold gauge pressure. |
| 06:01 | Again this is Link's preference by default, up to personal preference here, if you are more comfortable, absolutely you could make both tables just use manifold absolute pressure. |
| 06:10 | I'm going to leave it as default, really doesn't make too much difference, particularly if you're not seeing massive fluctuations in altitude where the baro pressure will change. |
| 06:19 | Alright so what are we going to do with this table? Well what we want is to make sure that we've got safe values in this table so that we're really unlikely to run into problems with detonation while we're getting up and running and starting to tune. |
| 06:33 | So again I've highlighted the whole table by pressing or clicking in this top left corner here. |
| 06:38 | And what we're going to do is let's just set the entire table for the moment to a value of 15. |
| 06:43 | That's going to be really super conservative, particularly at low load and vacuum, probably for example in the cruise areas, maybe somewhere around about here, probably going to find that we want to be in the mid 30s, maybe even more advanced than that so we're going to be very conservative there but that's absolutely fine. |
| 07:02 | As we move down this table, and in the default setup from Link as we go down the table, the load actually increases. |
| 07:12 | A little bit counter intuitive to me, you can change this if you prefer but this is the default setting. |
| 07:16 | But as we go down in this table, we may find that in some instances, particularly at relatively high boost and low RPM, this area here, 15° may still be a little bit aggressive for our engine so what I'm going to do here is, again I'm not getting too fussy because remember we are going to be listening for knock while we're tuning this thing as well so from 160 kPa, so that's 0.6 of a bar of positive boost, let's just set that to 12° out to 4000 RPM and that should be, again, there or there abouts, we should be pretty safe with those numbers and again as we get up and running, if we find that we do need to adjust these numbers because we've got some light knock coming in, easy enough to come back and address this at the time and make sure that we're nice and safe but this should be a pretty good starting point, really conservative values so that we should, for the most part be able to pretty well ignore our timing while we are getting our fuelling dialled in. |
| 08:18 | Alright so that's the main two tables that we're going to be dealing with here, our fuel and our ignition but you'll remember I've already talked about our open loop air/fuel ratio target table and how that interacts with the fuel table in particular so it's really important to make sure that we've got that set up correctly as well so let's press escape and we'll type in AFR and that's going to autofill with our AFR lambda target table so we'll click on that. |
| 08:45 | And we've already seen this table, couple of things that are important to keep in mind, we want to make sure, at least for our instances here, that the load axis is sensible, in other words we want this to be manifold absolute pressure or manifold gauge pressure. |
| 08:59 | We want to make sure that it isn't by default set to throttle position or something of that nature because that's going to obviously be no good for us. |
| 09:07 | So again break points here, not too critical, we don't need to be too fussy, looks like the default break points are absolutely fine. |
| 09:15 | You'll note here that the maximum value only goes out to 7000 RPM which with an engine that revs to eight, might be maybe a bit of a red flag to you but rest assured that's not a problem. |
| 09:25 | If we do end up going out to the right past 7000 RPM, simply holds the existing value, so not a real big issue there. |
| 09:33 | Let's have a look at our values here so for a start what we're going to do is we're going to richen our target at idle here so I've just highlighted 30-70 kPa out to 1000 RPM. |
| 09:46 | Set that to 0.96, just find that that settles the idle characteristics a little bit. |
| 09:52 | The other thing is we need to consider our fuelling targets in the vacuum area. |
| 09:57 | This is a little bit tricky for this particular application because the car is going to be used in competition, it's also going to be used on touring stages getting from one of the competition stages to another so fuel consumption is important. |
| 10:10 | What I'm going to do on that basis here is I'm going to leave our target set to lambda one up to 3000 RPM and then at higher RPM, in fact I'm going to do that all the way up to 4000 RPM and then 5000 RPM and above, what I'm going to do is set those lambda targets to 0.95. |
| 10:31 | So what that's going to mean is that when I'm in overrun, and this will sort of play into our anti lag setup when we get to that point, this is just going to add a little bit of additional fuel here, it's going to be using that additional fuel for cooling and that's going to be important help with our engine reliability but in this area here where we are genuinely cruising we will have good lean mixture targets so that we're going to get good fuel economy. |
| 10:56 | And because I'm a little bit torn here with this 4000 RPM zone, so that's OK, let's have a look here, what we can do is we can change that to 3500 RPM, probably unlikely that I'm going to be cruising above 3000 RPM and now as we go above 3000, we're going to actually start interpolating from lambda one down to 0.95, if I want to get a little bit more granular, what I could do is make this zone here just 5000 RPM, we could make that 4000 RPM and that'll just mean that that interpolation happens a little bit quicker. |
| 11:30 | Alright so that's our overrun area, our cruise area and our idle areas dialled in. |
| 11:35 | 100 kPa, 0.95 lambda, yeah I'm pretty happy with that, I'd probably be there or there abouts anyway so what we're going to do is make sure that our targets for the rest of this table are pretty safe. |
| 11:47 | So I'm going to go with 0.80 at 190 kPa and then above 190 kPa, let's go to 0.78. |
| 11:55 | I do find that the Subaru engines do respond or do prefer to run a little bit richer than some other four cylinder engines to I do tend to be a little bit richer on these than typically I would otherwise. |
| 12:10 | 160 kPa, let's just set that to 0.86 is probably pretty good, we're only transitioning through there, unless we're running our base wastegate duty cycle or something of that nature. |
| 12:23 | And let's just set 130 kPa there to 0.90. |
| 12:29 | Again we can come back and set these, change these to suit at a later point if we do see the need but for now, this should get us up and running and be pretty good starting point. |
| 12:41 | The worst case scenario is if we haven't dealt with this table and the numbers are all over the place and we're starting to tune our fuel table to get targets we want that don't actually match this which is very easy to do if you don't understand this interaction. |
| 12:53 | That can start getting yourself into a bit of a problem. |
| 12:56 | Alright so we've got our AFR lamba target table dialled in, we've got our fuel table dialled in, we've got our ignition table dialled in. |
| 13:05 | Couple of other little auxiliary tables that I do like to just consider and address which is some of our corrections as well as our limits so let's press the escape key again. |
| 13:16 | And what we'll do is start with our engine protection here and really the two elements that we want to consider are our RPM limit and our MAP limit which we can see down here. |
| 13:28 | Before we get into the actual tables let's actually have a look at our RPM limit for a start and how this is going to work. |
| 13:35 | So really important to consider the mode and I am a pretty big advocate where possible of making sure that our limiters are very very soft on the engine so that's why this is set to fuel cut, this is actually default but you can also alternatively use ignition cut. |
| 13:52 | Problem with ignition cut is it can be potentially damaging to some valve trains so wherever possible, or if in doubt, make sure that I'm always using fuel cut. |
| 14:02 | We've got the ability to have dual tables as well if you want to have an adjustable rev limit, we don't need anything like that. |
| 14:10 | And advanced mode as well which if we turn this on, and I wont' for the time being, it gives you a lot more control over the actual limiting process and how it works. |
| 14:18 | The default values though should be abossolutely fine for our application. |
| 14:23 | Obviously we've got exactly the same control for our MAP limit as well. |
| 14:26 | So let's have a look at these tables and 2D table here for our RPM limit vs our engine coolant temperature and realistically here, couple of ways of dealing with this. |
| 14:37 | Particularly if you're a little bit nervous and you're just getting started with tuning, I would suggest just starting by setting everything down a little bit. |
| 14:45 | Start with 5000 RPM, what this means is that if for any reason things get away on you, it's not going to end up sitting on an 8000 RPM rev limiter while you sort that out. |
| 14:55 | And then obviously once you actually get to a point where everything's dialled in up to 5000, then you'll need to bump that. |
| 15:02 | In our case, I'm going to actually start by setting this to 8000 RPM, I'm pretty comfortable with how this is all going to go and we can still come back and address this later on. |
| 15:12 | Now other option here is to bring in some sort of engine protection by dropping our rev limiter down where the engine coolant temperature is lower and this can just artificially stop someone from driving the engine really really hard when it is still warming up. |
| 15:27 | So for example down at 20° we might want to limit the RPM to 5000. |
| 15:32 | Now this is a personal preference, I would warn that if you are going to do this, particularly for a customer car, always a good idea to explain to the customer what you've done and why you've done it because otherwise you're almost guaranteed to get a call or a text saying hey, I started by car and it won't rev, what's going on? So just how you use this, again totally up to the individual. |
| 15:52 | Likewise you could do a bit of engine protection at the other end of the spectrum here. |
| 15:56 | By default you can see that at 110°, engine coolant temperature, RPM limits drop to 3000, 2000 and then 1000 so while that can be frustrating out on the road, racetrack or a rally stage, can also be enough to actually save your engine which generally will make up for the slight inconvenience. |
| 16:15 | Alright so we've now got an RPM limit that we know's going to be a good, safe starting point. |
| 16:20 | Let's have a quick look at our MAP limit table and again 2D relative to our coolant temperature, everything I just said still goes for making sure that your customer's aware of how you've set this up. |
| 16:33 | What I'm going to do here is set the entire table at the moment to a value of let's say 200 kPa which is one bar of positive boost. |
| 16:42 | Now this one, I would be a little bit cautious with, particularly if you've got a boost controller plumbed in, particularly if you haven't plumbed that boost controller in, or even if you have and you do the usual and don't actually read the manual properly. |
| 16:56 | In my experience with 15, 20 years now of tuning cars for customers, the plumbing of a boost control solenoid or boost controller is almost always done incorrectly and what this can result in is when you first start running the engine, basically zero boost control, the boost will just skyrocket to the moon which obviously if you don't catch that quickly, can be really damaging so I would recommend always starting with a nice conservative boost cut so 200 kPa there. |
| 17:26 | At the same time, always really important to keep in mind that you've set this because once you've got the base duty cycle, wastegate duty cycle set up and on your minimum boost and you start bringing that boost level up slowly but surely, obviously if you want to run over 200 kPa which we absolutely do, you're going to end up hitting that boost cut and that's going to be frustrating if it takes you a few goes to figure out why the engine's suddenly seemingly misfiring. |
| 17:52 | So 200 kPa for the moment, absolutely happy with that, we'll press F4 and we'll store those changes. |
| 17:59 | So at this point we've really got our base configuration of the important tables done. |
| 18:04 | Remembering again, really at this stage we're just getting some broad values in here that'll be enough to get the engine up and running, none of this is set in stone, we can easily come back and manipulate it and change anything that we need to once we get up and running so don't think this is basically done and now we can't adjust it, it's just enough to get some broad values in here that should be enough to get our engine running before we actually start going in and fine tuning everything. |
| 18:29 | Let's move on with the next step of our process. |
