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Practical Standalone Tuning: Step 3: Base Table Configuration

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Step 3: Base Table Configuration

07.38

00:00 - Our next step is to make some base configurations for our fuel and ignition tables.
00:06 We want to just get these set up with sensible break points and we also want to get some values into these tables that are going to be good safe starting points for when we actually get the engine up and running and begin our tuning.
00:19 So let's go through that process now.
00:21 We'll start with our fuel table here.
00:24 Now there is already a default table setup here.
00:28 Let's press the X key and that'll bring up our table axis setup.
00:33 Now in this case we've got, obviously engine speed on our X axis, we've got manifold gauge pressure on our vertical axis which is the parameter that Link recommend for turbocharged or supercharged engines, and what this does is it gives us a gauge pressure relative to the onboard barometric air pressure.
00:54 So in this case, negative values are in vacuum, zero is our current barometric air pressure and as we move into positive boost pressure, our values become positive.
01:03 So what we've got here, we can see our values, we've got every 20 kPa, I've added in another zone here, another break point at -70 and also -50 kPa, just to give us a little bit more resolution around those idle and cruise areas.
01:21 We can see as we move down here, as we go into positive boost pressure, we've got these values just consistently at 20 kPa.
01:30 Now if we look at our engine speed, again I've got this set up relatively broadly at the moment, we can see that for the most part we've got values every 500 RPM.
01:41 We can see that I do have an extra zone at 750 and an extra zone at 1250 RPM.
01:47 And this just helps give a little bit more resolution again around that idle and that tranisition from idle.
01:53 Now in this particular engine, we're expecting to potentially use as much as 8500 RPM.
02:00 So I'm just going to add some additional zones here and we'll take that out to 9000 RPM.
02:06 It's always a good idea just to make sure that you've gone a little bit beyond your expected engine rev limit so you've got some resolution in your table.
02:15 We're gonna click OK now and the ECU will ask if we want to interpolate our values.
02:22 Now to get us a starting point here, what I'm going to do is just select the entire table and we'll set the entire table to a volumetric efficiency of 50%.
02:31 And this should be enough, broadly, to get us up and running and we'll be able to start tuning from there.
02:38 Let's switch over to our ignition table now and we're going to make the same setups there.
02:45 I'll press the X key.
02:47 This time with our ignition table, we don't really need to be quite so precise and you can see that I've got values every 20 kPa.
02:54 Just got a stray value in there at 170 and I'm just going to remove that by pressing the X key and we're using in this instance manifold absolute pressure instead of manifold gauge pressure for our load axis.
03:10 Our engine RPM is the same as what we saw with our fuel table and again I'm just going to add in a couple of additional zones there to take us out to 9000 RPM.
03:22 Now we want to start here with some safe numbers in our ignition table.
03:28 So what I'm going to do is just select all of the areas up to 100 kPa and I'm going to set them to 15 degrees, and I know that's going to be nicely safe and retarded there, it's not going to cause us any trouble.
03:45 What I'm going to do though is be a little bit more conservative as we move up into boost, and particularly with this engine running quite a high compression ratio of 10:1, and pump fuel, we want to be quite conservative with our ignition timing.
04:00 So what I'm going to do here is set our ignition timing at 240 kPa to two degrees.
04:07 And then I'm just going to interpolate between 15 degrees at 100 kPa and two degrees at 240 kPa.
04:15 I can do that just by highlighting the entire block of values and pressing control and I.
04:19 So this will just give us some numbers that should be nice and safe.
04:24 Of course we always want to be using audio knock detection equipment while we're doing our tuning anyway to safeguard against the potential that even with our conservative timing, we may still have some knock occur.
04:37 OK so we've got our fuel and our ignition table set up and configured.
04:41 There's a couple more that we need to look at here.
04:44 And we're going to move over to our air fuel ratio or lambda target table.
04:48 And this, with a volumetric efficiency or modelled fuel system, needs to be tuned to suit whatever target air fuel ratios we expect our engine to run.
05:01 So you can see here, I've already got our table relatively configured.
05:05 We've got manifold pressure on our vertical axis and we've got engine RPM on our horizontal axis.
05:12 We can see in the cruise and idle areas I've got a target of lambda one.
05:18 Because this engine is also equipped with some large cams, what I'm actually going to do is richen my target at idle to about 0.95 And of course because this is a race car, we're predominantly going to be operating it fairly hard so we're not as worried about our economy in the cruise areas anyway.
05:39 OK we can see that as we move down, our target air fuel ratio does become richer and when we get out to 300 kPa, we've got a target of 0.78 lambds.
05:52 Of course you can set your air fuel ratio targets to whatever you're comfortable with and this is only a starting point as well.
06:01 Of course we have the opportunity once we've tuned the volumetric efficiency table to simply adjust out air fuel ratio targets directly inside this table.
06:11 So we can experiment and find out exactly what air fuel ratios our particular engine wants to run.
06:18 There's a couple more aspects we're going to look at and first of all we're going to go to our RPM limit table.
06:25 And it's really important that we always have a safe RPM limit set for our engine before we start it up.
06:33 And particularly when we're first getting our engine running, it's sensible to actually reduce this RPM limit down so that we're not going to accidentally rev it too far.
06:43 So I'm going to set our RPM limit initially to be 5000 RPM.
06:49 The other aspect we're going to look at is our MAP limit.
06:53 And we can go through and set a manifold pressure limit or an over boost limit just to protect our engine again in case the boost does become excessive.
07:05 So we can do this by going to our MAP limit table and we've got a two dimensional table here relative to engine coolant temperature.
07:15 For a start, what I'm going to do is set that entire table to 200 kPa.
07:20 So that'll just ensure that if something's wrong with our boost control system, we're not going to end up with excessive boost pressure.