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Practical Standalone Tuning: Step 3: Base Table Configuration

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Step 3: Base Table Configuration


00:00 - The next step of our 10 step process is to configure our base tables so that we're getting close to being able to start the car and get it up and running for the first time.
00:09 This is an area that I know a lot of enthusiasts really worry about, thinking they're going to have to have the perfect numbers in these tables or the engine's going to be damaged the instant we try and start it.
00:20 The reality is nothing could be further from the truth.
00:22 It's going to be very difficult and most likely impossible to damage the engine during cranking and initial start up so we can easily adjust these values as we require once we actually get to the point of starting the engine for the first time.
00:36 Likewise our axes break points, these don't have to be perfect, particularly in our instance, we've got a VTEC setup here and we're going to almost certainly need to move around our axis break points as we get up and running and find out where that VTEC changeover optimally needs to be.
00:53 Again we'll see more about this as we get into the actual tuning of the engine.
00:57 So it's very easy to adapt these tables, make changes as we get up and running, for now we just want a base setup that's going to allow us to get the engine running in the first place.
01:08 Let's jump into our MTune software and have a look at how we're going to be doing this.
01:12 So at this point we're going to be moving down into our tuning section of our menu structure and menu tree and let's start considering it's already highlighted with our fuel table.
01:24 You will notice, because these are three of the tables we're going to be using the most, that there are hot keys for these.
01:30 F5, F6 and F7, just making it really easy to jump between these tables without actually needing to use that menu structure once we're up and running, tuning on the dyno.
01:41 Looking at our table out here on the right hand side, looks exactly like you'd probably expect, we've got our RPM on the horizontal axis and we've got manifold absolute pressure on our vertical axis.
01:53 We can also display it in a number of different ways and we've got some little buttons out here on the right hand side.
01:59 At the moment we're looking at a 2D numerical display, we can on 3D, that will give us a table in a 3D view and then we can also use a combination of the 3D and 2D graphical and numerical display.
02:13 Personal preference comes into play a little bit here, there are pros and cons of using each and in general it can be actually beneficial to see both views like we're looking at here.
02:23 The reason for this is that obviously when we're looking at a 3D table, we don't see the specific values so it's nice, particularly with a VE based fuel model, to actually see what the specific value we're tuning is.
02:35 However it's also quite easy with a numerical display only to actually inadvertently enter a wrong number and that's not going to necessarily jump out at you when you're looking at a table of numbers.
02:48 It'll be very obvious if we have a big hole in that table, let's say we've got this value here and instead of 77 we've entered a value of seven.
02:57 So straight away we see this big hole here and we know that we've got a bit of a problem.
03:01 It is helpful though that even the values in the numerical table are colour coded to just help make that a little bit more apparent.
03:10 For the time being I'm just going to come back to 2D, as I've mentioned this is a bit of a personal preference thing.
03:16 Now we'll have a look at our axes and our scaling.
03:19 In our instance here, we've actually already got the fuel and ignition tables set up with a correct load parameter which as we already saw is manifold absolute pressure.
03:28 Now we can easily edit that though if we don't want it to be MAP.
03:32 Let's say we're tuning ITBs and we don't have a valid manifold pressure signal so we're going to need to run alpha n where we're going to be using throttle position as our load axis.
03:42 We come over here to the load axis, right click on this and we can come down here to change axis source.
03:50 Click on that and what we can do is just enter throttle and that will just reconfigure our menu and we can see here we've got throttle position as the parameter that we would want to use there.
04:03 I'm not going to do that but that just shows how you can do that, or choose any other axis that you'd prefer.
04:09 Next we have our actual break points and what we've got at the moment's actually pretty close to the mark, it's not too bad but we can see we've probably got a few zones that we don't need.
04:19 We've got a zone at 45 kPa and a zone at 85 kPa, probably a little bit tighter than what we actually need to let's have a look at a few of the ways we can manipulate this so let's say for example we want to get rid of this 85 kPa zone, this break point here, we can click on that, right click and what we can do is go down to remove column or row and that will allow us to remove that 85 kPa break point.
04:45 Let's do that again, we've got a 45 kPa one here, we can remove that as well.
04:52 Now if we want to instead add in we can go and do that a number of different ways so we've got 50 here, we'll right click on that, we can insert a column or row before so obviously in this case, that would insert one before 50 kPa, it interpolates, it'll be between 40 and 50, hence 45, click on that, that does that, likewise we could click on our 80 kPa site here and we can click on insert row or column after, of course that would be between 80 and 90 so it gets us back to essentially where we were.
05:24 If you're starting from scratch, the other option you can do here is come down to rescale axis and that will allow us to set our lowest value, let's say 0 kPa, our highest value, let's leave that at 100 kPa and then we can change the number of cells if we want.
05:41 Let's click on that, so we can have a cell division of 10, that's going to give us 11 cells, maybe we want to have a cell division of five, that will give us 21 cells so let's just start here with 10, click on that and that's just going to give us a nice even interpolation from our minimum and our maximum 0-100 kPa.
06:01 Now this is probably a little bit of overkill here.
06:04 For example at the higher load sites, we probably don't need such tight resolution.
06:10 Let's just make some changes here and we will remove the 70 kPa site here.
06:16 Likewise we might want a couple of sites a little bit tighter down in the idle or cruise areas so let's just for example show, we could add one here at 25 kPa by inserting a column or row after and again we can come back and make further changes to this as we see fit.
06:34 Now let's look at the horizontal axis here, our RPM axis and generally as per the body of the course, I recommend keeping our zoning around about every 500 RPM and that's exactly what we've got.
06:46 Expecting to run this engine out to maybe 8500, 8800 RPM so we want to make sure that we have a zone that just extends a little bit beyond that but let's say we want to go a little bit further, we can then insert another column after that.
07:02 It'll add one at 9500 RPM and what it does as well is just extends or interpolates our fuelling as well so might not be quite right but at least it puts some numbers in there.
07:12 Now I have also got another site here at 750 RPM so it's always a good idea to have a little bit of additional resolution in our table down in the idle area to give us precise control.
07:23 What we haven't got in here, which we will be adding later on, is that around the VTEC changeover point we're going to want to probably almost certainly have some tighter resolution.
07:34 Let's say we switch at 4000 RPM from our low cam to our high cam, now that may result in at some point in the load a reasonable step in our VE so what we might want to do there is have a zone at 4000 RPM and then another zone at 4050 or 4100 RPM and that'll just give us tighter control to make sure we don't have a momentary lean or rich area as we step through that VTEC changeover point.
08:00 This is a good time to just stop and talk a little bit more about how we are dealing with the cam switching or VTEC here.
08:08 Obviously we are tuning a Honda B18C but this really goes for any manufacturer's switched cam control mechanism, so maybe it's a Nissan VCT, maybe it's a Toyota, it doesn't really matter.
08:22 This is different however to continuously variable cam control so just want to point that out.
08:29 But there are a variety of options.
08:32 I've already talked about the fact that for this worked example, we're keeping it nice and simple, we are purely switching our VTEC or cam switching based on RPM solely.
08:42 But that's not the only way we can do it and if we actually investigate how Honda do this, they essentially window the VTEC changeover point and what I mean by this is that it incorporates both RPM and load.
08:55 And if we actually want to get really granular with things we'll find that the optimal VTEC switchover point at wide open throttle or high load, let's say 100 kPa, that's going to probably almost certainly be lower in the RPM range than where we would want to switch the cam control if we're at half throttle or 30% throttle, lower down in the load.
09:17 So we can do that but if we're going to do that and incorporate a second parameter such as manifold pressure or throttle position in our VTEC control strategy and we looked at how that works already then this gives a few inconsistencies in how we're going to be dealing with it inside of this table.
09:36 Let's say for example that we switched at 4000 RPM which is right here at 100 kPa but maybe at 20 kPa we don't want to switch until 6000 RPM, that sort of gives us a bit of a line through our VE table like that and it makes it tricky but not impossible to do all of that tuning really nicely inside of one table.
09:57 So there are options around this, we can switch to a completely second table, completely different table for our fuel and ignition based on our VTEC point.
10:07 There are a couple of ways we can do this and what I'll show you is how we can do this using the 4D axis in the MaxxECU.
10:16 So all we want to do here is start by right clicking and we want to come down to the bottom here to 4D axis and add 4D axis and that gives us our 4D axis over here and by default that's just jumped to ethanol concentration so this is great if we were tuning flex fuel but that's not what we want to do here so what we can do is change the source for that fourth dimensional axis, right click on there, come down to change axis source and again we've got all of our options here, easiest just to search for what we've already called it which is VTEC and we've got our PDM output so we can see we've got our state, our current and our voltage, of course we want to switch on the state change so we will choose that option, click OK.
11:00 Now this is currently scaled between 0 and 100%, makes sense for ethanol.
11:06 In our case the state is changed between zero, off and one for on so we need to make that adjustment as well.
11:13 We'll click OK, now we've got our 4D axis set up that will change on our VTEC condition or VTEC state and we can see at the moment it is in the zero state because it is off.
11:25 So what this gives us now is two completely separate maps, if we click on our 4D axis, state one, we jump to our second table, now nothing changed because these tables currently are exactly the same but let's say we're going to just highlight a large section of this table and let's set it to 20 just so we can see that change take place.
11:47 So at the moment we've on our high VTEC or high cam table, click on zero, we jump back to our low cam table.
11:54 We can also have completely different RPM and load break points if we want between those two tables and traditionally if we see how Honda do this, the scaling or break points for our low cam will be relatively tied up to maybe 4500, 5000 RPM and then get a little bit more sparse because essentially we're unlikely to be operating there and conversely on the high cam table when we are on that high cam, we're going to have tighter break points and more accuracy between 4000, 4500 RPM up to 9000 RPM and a little bit more sparse down below.
12:27 Now this adds some complexity to our tuning.
12:30 Makes a little bit more work for ourselves and it's not strictly necessary.
12:33 What this does do is gives us a little bit more freedom around switching the cam on and off and if we tune the engine thoroughly with the VTEC both enabled and disabled, it's going to mean that if we want to disable the VTEC when the car's stationary which also Honda do or maybe when our oil temperature's low or any of a number of other factors, we can do this and the volumetric efficiency of the engine is still going to be accurate.
12:59 Now again for our worked example, I'm not going to be demonstrating this, it's going to add a lot more work but you've seen now how you can do this.
13:07 Of course if you want to be completely thorough, you could do this on our ignition table as well so for now what I'm going to do though is disable that and we'll come back to our nice simple setup for our tuning.
13:19 Alright so at this point we also need to put some numbers in here that are going to be enough to get the engine up and running but as I mentioned this is the bit that I know people get a little bit worried about.
13:30 This is a volumetric efficiency based ECU which makes our tuning a little bit easier because we are actually taking into account the airflow into the engine or the mass or air entering the engine, the engine capacity and what size the fuel injectors are.
13:45 Now generally what this means is that we can go ahead and highlight that entire table and what we can do is enter a value of something like maybe 50 or 60%, it's not going to obviously be correct but this should be enough to at least get the engine to start and to idle then we can make some block changes as required from there.
14:06 OK so that deals with our fuel table, let's move on and we'll have a look at our ignition table.
14:12 We'll come back and look at our lambda in a moment.
14:15 So our ignition table, everything you've just seen in terms of how you can adjust or manipulate the load axis or the break points is exactly the same, if we have a look here, we've got break points every 10 kPa, again probably a little bit tighter than what we need, let's just remove one here at 70 kPa, we'll leave everything else as it is, again we've got break points every 500 RPM for the most part, we've actually got a slightly tighter break points down in the idle area, let's see how we can change that.
14:51 Now we can actually edit an existing break point as well, let's edit that and instead of 1600, let's call it 1500 and let's just keep things nice and even, we'll call this 1250 RPM and then we already had a fuel break point at 750 RPM which might be where we'll be idling when the engine is cold, remembering we don't have an idle speed control motor on this engine so let's add a break point here before and that'll nicely interpolate there.
15:21 Actually looking at this, I overlooked the fact that we had one here already at 800 which is why that's interpolated there and of course between 800 and 1000 we've got a break point at 900 now so that's OK, let's just edit these.
15:35 This is how quick and easy it is to make changes as you see fit.
15:40 We want that one actually to be 500 RPM and then this one here to be 750 RPM.
15:48 Now what that's going to do as well is interpolate these numbers in the actual table as we make these changes so essentially we should have no effect on our tuning until we make changes in the actual table.
16:01 Now let's look at the numbers in the table itself and you can see at the moment, what I've got is that table entirely filled with a value of 15 so this is just a nice safe number that particularly on the 100+ octane pump fuel we're running on here, given the compression ratio was stock, we should be pretty safe from detonation in this engine.
16:21 However just while I'm getting started, what I'm going to do as well is at lower RPM, just come up to 2000 RPM and down to 60 kPa, we'll change those numbers to 12 just to give us a little bit more of a safety margin there and of course as we go through and tune this engine, we will be using knock detection anyway, audio knock detection so I can actually listen in and make some adjustments to our timing as we see fit.
16:46 The idea here is always to start with safe retarded ignition timing and advance towards MBT and then we can either find MBT or the knock threshold and back off from that, we never really want to be starting with over advanced timing.
17:02 OK so our ignition table and our fuel tables are now set up, got some base numbers in there that should be good to get us running.
17:09 Let's lastly have a look at the third of our main tables which is our lambda target table.
17:15 Now this works in conjunction with a volumetric efficiency based fuel model in that we need to set this accurately to suit our real air/fuel ratio or lambda targets.
17:27 If this table hasn't been adjusted and we're fudging the numbers in our fuel table to actually get a lambda value that we want but not necessarily what's in this table, is going to result in some inaccuracies in our VE and of course if we do want to incorporate closed loop lambda control at a later point of course that's not going to work so this does need to be set up properly.
17:50 Now the break points here don't need to be quite as tight or quite as accurate as what we've looked at with the fuel and ignition tables.
17:57 Of course the ECU interpolates between zones anyway and generally we don't need to want to make really dramatic changes in our lambda targets across a short change in load or RPM so let's have a look at this.
18:12 And start with our wide open throttle area of operation which is in the 190 kPa zone.
18:18 So what I'll do here, and this is really coming from my own experience with tuning 100s of these engines, we're going to start up to 4000 RPM with a lambda target of 0.92 then what we're going to do is from 4500 up to 6500 we'll richen that up to 0.90 and then 7000 and 7500 RPM and above, we will richen that again to 0.88.
18:42 Now of course if we end up running off the end of this table, 7500 RPM, obviously we're going to be revving beyond that, we're still going to be extrapolating these numbers so it's not like it falls off a cliff and has no values, it will continue with that value, that's why we don't need to have this scaled out necessarily to 9000 RPM.
19:01 However, if you do want to, absolutely no problem, let's make that 9000, now we've got our complete range of operation covered.
19:09 In our idle areas which I'm going to class as 60 down to 20 kPa and up to 1500 RPM, I'm actually going to leave this as 0.95 lambda.
19:19 I find, particularly if we did fit a set of aftermarket cams which were a little bit more aggressive, the slightly richer target seems to help these idle a little bit better.
19:29 So we'll leave that unchanged and for the most part, for a race engine we may actually want to leave some of this lighter load area a little richer than stoich anyway just to help with cooling.
19:42 In our intances here, what we're going to do is we'll go up to 4500 RPM and we'll set that to lambda one.
19:50 We've sort of already generally got a nice interpolation as we move up to 80 kPa, 0.95's probably about where I'd want that to be anyway and likewise at higher RPM, we want a slightly richer target there in overrun or light throttle just for that cooling effect but of course you can set these to whatever you want, it's always advisable to at least have a ballpark of where you want the engine to be before you start tuning but obviously later on we can come back and we can manipulate these wide open throttle running lambda targets and see if the engine's going to respond better with a slightly richer or a slightly leaner target, these are never set in stone.
20:30 Lastly for our base configuration, we want to make sure we've got some limits set up just in case something goes wrong while we're getting the engine up and running so let's shut down or shrink down our tuning menu and we'll expand our limits menu and we've got a range of limiter options here.
20:47 Now we're going to have a look for a start at our rev limit and we can be as complex or as simple with this as we want so first of all we've got our rev limit RPM source.
21:00 So we've got that set to a single value at the moment, or we can have two values that are switch activated, maybe for a secondary RPM limiter or for a safety element if you want.
21:08 Or you can have a full table, we're just keeping our single value here and we've got that set to 8800 RPM.
21:15 What we may want to do, particularly when we're just getting up and running is we could bring this down to a lower value just to be a little bit on the safe side while we're getting the engine started.
21:25 If you do do this, make sure you remember this because once you start expanding your tuning out, it can be quite frustrating when you hit this and maybe it'll take you a little while to remember that that's right, I actually set a lower rev limit so just keep that in mind.
21:39 So we'll leave that at 5000 RPM for the moment.
21:43 Also worth talking about our rev limiter settings as well because this is quite important.
21:47 First of all, and probably most importantly is our rev limit type.
21:51 In this case we are using fuel, this is the safest option in terms of not being too harsh on the valve train.
22:00 With a lot of engines, the valve train is very sensitive to ignition cut and this can cause problems with rockers being popped off or shims being thrown off so if in doubt I always recommend using a fuel cut.
22:13 We've got the ignition cut or fuel plus ignition 100 RPM later or ignition plus fuel 100 RPM later, I'm going to leave that on fuel.
22:22 We also have the option to incorporate a dual mode rev limiter.
22:25 We've got our cut pattern as well, we can have a random or a sequential pattern, this just really refers to how the ECU is going to decide which cylinders to cut.
22:36 I'm going to leave that on random.
22:39 We've got our rev limiter control range as well so this gives a range of RPM over which the limiter will increase from 0% cut to 100% cut.
22:49 So the larger this is, the smoother the RPM limiting will be but of course it does incorporate a range of RPM.
22:58 The tighter we have this, if we set this to zero, you're going to have an instant 100% cut, that can be very very harsh as well so generally 100 to 200 RPM there is going to give you a good result, nice smooth limiter.
23:11 You can also incorporate ignition retard on the limiter and fuel enrichment if you see fit, I'm not using any of those.
23:19 We've also got a predictive rev limit option as well which we can either enable or disable, I've got that disabled so that's our rev limit setup, we've got that so that we're going to have a nice safeguard there of 5000 RPM while we're getting the engine up and running.
23:34 Probably the other one that I would consider incorporating here on a turbocharged engine that would make sense is of course our boost cut.
23:41 This is a naturally aspirated engine as we already know so there is no boost, we've got that disabled.
23:45 But certainly with turbocharged engines, the number of times I've seen problems with boost control with the wastegate maybe being plumbed wrong during the initial tuning is probably 10:1 with people getting this right so setting a sensible relatively low boost cut just while you're getting up and running, just to safeguard the engine in case there is a problem with the boost control is a really smart thing to do.
24:10 Alright at this stage we've got all of our base configuration done, our base table's set up and we can move on with the next step of our process.

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