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Practical Standalone Tuning: Step 3: Base Table Configuation

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Step 3: Base Table Configuation


00:00 - At this point we're ready to make some basic configuration changes to our fuel and ignition tables to get them ready for the point where we're going to start our engine for the first time.
00:10 Again in this instance, we are a little bit fortunate that we do have a base map for this MX5 however we're going to see how we can use the MegaSquirt ECU in order to set up any engine from scratch.
00:22 Now what we're going to do to start with is head to our fuel settings and we're going to click on that drop down menu and we've got two tables that we're going to need to configure, we've got our AFR table one here and we've got our fuel VE table one.
00:37 Now as I mentioned briefly, this ECU is now set up and configured as a true volumetric efficiency based fuel model.
00:45 So our fuel VE table needs to be adjusted until we reach our air/fuel ratio target.
00:50 So we need to understand the way the tuning workflow needs to be performed, as well as the interaction between these two tables.
00:58 Let's start however by bringing up our fuel VE table one.
01:02 Now at the moment we've got our fuel table with some volumetric efficiency numbers already entered into it.
01:08 We'll just have a quick tour of the table, it's pretty self explanatory, on our vertical axis here we've got our fuel load.
01:14 So this is just manifold absolute pressure.
01:16 And then of course we've got our RPM on the horizontal axis here.
01:19 Nothing particularly unusual.
01:21 And we've got our volumetric efficiency numbers in here.
01:25 Now you can see at the moment that this is spanned into positive boost which isn't strictly necessary.
01:30 We've got a couple of options that we can work around here when we are adjusting our break points.
01:36 What we can do is click on a particular break point and then we can just enter a new value in and that will respan the break point out to whatever we want.
01:45 So we can go through and set this up.
01:47 In this instance our RPM scale is basically where I'd want it, we've got basically 500 RPM increments at the moment, we can see we've got a little bit more detail down particularly around the idle target of 800 RPM.
02:00 Nothing particularly wrong with that, however we don't strictly need these positive boost values in our break points.
02:06 Now this is where we've got the option of having the MegaSquirt or TunerStudio software actually do some of the work for us.
02:13 So if we head to our tools dropdown menu here, we'll see we've got VE table generator.
02:19 Now we've got the ability here to let the MegaSquirt software, the TunerStudio software generate our break points as well as actually generate some base numbers to put into that VE table.
02:31 How you choose to use this is totally up to you.
02:34 For the purposes of this demonstration though we will use it because for all intents and purposes, this should at least get us up and running with some relatively sound numbers and of course we're going to be optimising each of the zones anyway so we're not stuck with what we get.
02:50 So let's talk through this, we're going to start by selecting our engine type.
02:53 So obviously here we are naturally aspirated.
02:56 I've made some basic assumptions here that our idle speed is going to be 800 RPM, at which point we're going to be pulling 35 kPa manifold pressure and our engine red line here is 7500 RPM.
03:09 I might actually pull a little bit lower than that but that will span us out beyond that point.
03:13 Then we're taking some rough guesses here of our peak power and our peak torque.
03:17 You can see I've listed those at 135 horsepower, 6500 RPM and 120 pound foot of torque at 4000 RPM.
03:25 These don't need to be accurate, again we're not going to be sending the car out on the road with these numbers in here but it will generate a starting point for our tuning.
03:34 In particular here if you aren't tuning on the dyno, if you are going to be tuning on the road, this should give you a reasonable shape to our VE table to get us up and running and for something that you can work from there.
03:45 Then we've also got our engine displacement so in this case of course 1600cc.
03:50 Now we can choose here to generate new X and Y bin, so basically our break points for our load and RPM axis or alternatively you can choose to use your existing break points if you'd prefer.
04:03 We'll allow the software to generate those bins now so we can click generate.
04:08 And we can see straight away it generates a new VE table for us.
04:12 Now in this instance we can see the break points that it's generated, quite small at the moment, they'll be applied in a second.
04:18 Does give us a little bit more resolution than we realistically need so it's a coin toss or personal preference between whether you want more break points in there or whether you want a table that spans out into positive boost which you're not going to be using.
04:32 With the MegaSquirt software you are restricted to using the number of break points available so you can't actually delete break points which is what I would normally do there.
04:43 So what we're going to do there is click apply to our VE table one, you can see that's done now.
04:48 Now because we have made a change there we can see we've got our little burn icon which I've already mentioned, we can also see in the background there on our gauge page, the little red status tag has come up there saying needs burn.
05:02 So this is essential in order to make those changes permanent so we've made those changes there.
05:08 You could just as easily use the technique taught in the course where we can highlight the entire table there and by pressing the equals key, we can now set all of our values to somewhere in the region of perhaps 50% or 60%.
05:21 Either way, we're going to be building up our VE table as we go.
05:25 I think it's worthwhile just showing the VE table generator as it is a nice function.
05:30 So what we'll do here, bottom left hand corner we can click the undo function.
05:34 That'll take us back to our generated table.
05:37 So that's our volumetric efficiency table set up.
05:40 Now as I mentioned, this goes hand in hand though with our air/fuel ratio target table.
05:45 So let's click on our fuel settings, we'll go down to our AFR target table one and we'll have a look at this table.
05:52 Now as you can see here, we've got the same situation with our break points being spanned out into positive boost.
05:59 We've got the other option here again of using our AFR table generator.
06:04 So we can go through that exact performance there, it's totally up to your own personal preference.
06:10 Now with our AFR target tables we don't need to be so accurate with the number of break points, there's no real advantage in having a huge number of break points in this table.
06:20 So for the purposes of this demonstration, I'm actually going to leave this with our table spanned out into boost.
06:25 Even though we are obviously only going to be using the vacuum area of this table.
06:32 So I've gone ahead and I've entered some numbers in this table already that are probably pretty representative of where I expect this engine to end up.
06:40 Remembering again we're not fixing our air/fuel ratio targets at these numbers.
06:44 We can easily go through once we start optimising our tune on the dyno and refine these further.
06:50 But important points to take away from this, what I've done here is I've set our idle target just a little bit richer than stoich there at 0.95.
06:59 I find that some engines do tend to idle a little bit smoother if we're just a touch richer than stoichiometric.
07:06 Of course we've got a reasonably large section of this table that is set to lambda one, our stoichiometric air/fuel ratio.
07:13 This incorporates our cruise areas and some of our part throttle or light load areas where we're really more interested in good fuel economy than we are in maximum power.
07:24 Then as we move up to the wide open throttle area of operation which in this case of course is 100 kPa, we can see that we progressively move richer.
07:32 And for simplicity at the moment I've just set our wide open throttle operating target there to 0.90 lambda, it's reverted to 0.898 but we're splitting hairs.
07:43 At high RPM and in light load I have targeted a little bit richer, just to help with some additional fuel for cooling.
07:51 Now you will notice here that our maximum RPM break point there spans only to 6000.
07:55 Now that's not to say that if we fall off the end of this table that we have no targets, these numbers that we'll see in the last column here, those will just be extrapolated out to the right.
08:08 Of course the other option there is we could just click on our final break point and span that out to 7500 RPM.
08:15 Really again, personal preference but just important to understand here that this table does interpolate so it doesn't need to be very very high resolution, we don't need to make dramatic changes to our air/fuel ratio targets across a narrow range.
08:31 So with that table deal with, we're going to close that.
08:34 What we're going to do now is click on our ignition settings and we're going to come down here to ignition table one.
08:41 Now in this instance we can see again we're in the situation where we are spanned out slightly into positive boost pressure, obviously we are solely going to be running through at around about this 100 kPa point.
08:53 Again I'm not too worried about the fact that we're spanning out into positive boost.
08:56 It's really again that personal preference as to whether or not you want to have more break points and higher resolution which really in my opinion for this particular engine, isn't going to give us any advantage.
09:08 So we've got our RPM break points and we can see again we're spanning out to 7500 RPM, we've got a little bit more resolution down in our idle area, our transition area.
09:18 Particularly I've got a site there set at 1250 RPM.
09:22 What I'm going to do for a start here is highlight the entire table there and we're going to hit the equals key and we're going to start by setting our values there to 15 degrees.
09:34 Now again this should be a good safe starting point as we begin our tuning.
09:39 We're going to burn those changes to the ECU and we can close that table.
09:44 Now the last table we're going to have a quick look at here is if we just head back to our basic/load settings and we're going to come down to our rev limiter table.
09:54 Now it's a good idea just before we start tuning to just make sure that you've got some basic RPM limits set into the ECU so if something goes wrong, you don't find out the hard way that the RPM limit wasn't set at all or it's set to something ridiculously high like 10,000 RPM which would result in engine damage.
10:13 So at the moment you can see we've got a hard limit set at 7200 RPM.
10:18 So I'm more than comfortable with that.
10:20 We can close that down.