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Practical Standalone Tuning: Step 3: Base Table Configuration

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Step 3: Base Table Configuration

10.20

00:00 - Our next step is to do some basic configuration of our fuel and ignition tables and set this up how we want it to be before we get started with the actual tuning.
00:10 Now, remember we don't need to be too worried about the exact configuration of our tables at the moment because once we start tuning we decide that we need some extra resolution in some areas of the map it's a simple task to add more zones around those particular areas.
00:30 We're gonna start by looking at our VE table or Volumetric Efficiency table here so this is where we're going to be defining the engine's volumetric efficiency which in turn helps control the fuel delivery.
00:45 You can see we have our Manifold Air Pressure Manifold Absolute Pressure on the vertical axis and we have our Engine RPM on the horizontal axis.
00:56 If we want to make changes to the axis and the set points on the axis we can right-click and we have the option to Add Column, Remove Column, Add Row or Remove Row.
01:09 So let's just try that let's remove the 1,250 rpm column and we're going to do that by selecting the 1,250 rpm column from this dropdown list and click Ok, that removes that particular rpm column and then reinterpolates the rest of the cells around it.
01:34 Likewise if we wanted to add a particular site we can do by right-clicking and clicking Add Column or add the 1250 rpm column back in and then that changes made.
01:49 Generally as a good starting point I'd suggest having load zones of about every 20 kPa and rpm sites around about every 500.
02:00 So why's with while adding some extra resolution around the Idle and Cruise areas and you can see I've done that by adding a 750 in the 1250 rpm column that we just looked at.
02:14 Likewise, we got slightly tighter resolution in the load zoning around the Idle and Cruise areas as well.
02:22 We've got a 30, a 35 kPa zone added in there just to give us a little bit more control.
02:30 And we don't need to worry too much about the actual numbers in this table just yet we're going to look at how we can adjust that a little bit further into the process.
02:41 So it takes care of our Volumetric Efficiency table which is where we're going to be indirectly controlling the fuel delivery.
02:49 Let's swap across now to the Ignition Map tab.
02:53 We've got the same style of map for our ignition timing.
02:58 Again, we've got Manifold Pressure and we've got Engine RPM.
03:04 And I'd again suggest using similar zoning.
03:07 With the ignition timing you'll remember from the main body of the course, it's actually not quite so critical to have such fine control over the ignition timing as perhaps the fuel delivery because the engine is a little less susceptible to changes in our ignition timing.
03:25 So again, a good starting point would be every 20 kPa in every 500 rpm.
03:31 For the sake of completeness and demonstration you can see we've actually got slightly finer resolution on our load axis it's not strictly necessary as we're going to see once we actually start running the car and tuning it.
03:46 Remember that the ECU will interpolate between surrounding cells and that's why we don't have to have incredibly high resolution, enough fuel or ignition tables when the ECU is operating.
03:59 So when the engine is operating between adjacent cells the ECU will be interpolating between those cells to decide on the correct volumetric efficeincy and the correct ignition timing values.
04:13 As one more table that we do need to look at here and this is our Lambda or Air/Fuel Ratio Target table.
04:21 This is critical to the operation of a volumetric efficiency-based ECU and in this particular table here we are defining the Lambda value or Air/Fuel Ratio Target that we want the engine to be running.
04:37 And again you can see we've got the same axis, we've got the Manifold Absolute Pressure versus Engine RPM.
04:44 And what I'm going to do here is first of all remove the 110 kPa row because obviously with our naturally aspirated engine we're not going to be operating in positive boost pressure so we can get rid of that particular row.
05:02 So we want to do here is configure the Lambda targets that we actually want the engine to be running and this is a really critical step in tuning a VE-based fuel model.
05:18 We need to choose these Lambda targets accurately and then in turn once we've done that we would then churn the VE table to achieve these Lambda targets.
05:29 So this is the first place we need to make our tuning adjustments.
05:34 And you can see here I've already pre-configured this table and what we're doing is in the Idle and Cruise areas you can see that we have a target of Lambda 1.00.
05:47 It's going to give us good fuel economy and low emissions.
05:50 As we move up the table however you can see that in the 90 and 100 kPa areas we're targeting 0.87 Lambda and as we move to the right and go into higher rpm we're actually moving a little bit richer we're now targeting 0.85 between 6 and 8,000 rpm at 90 to 100 kPa.
06:15 What I've done here is then interpolated between the Lambda 1 at 60 kPa and the Lambda 0.87 at 100 kPa.
06:28 And we can interpolate by simply selecting the cells that we're wanting to interpolate and if we right-click you can see that we have our Interpolate options there is a quick key-shortcut key for that so what we want to do is interpolate vertically here so we can do that by pressing the "V" key or selecting that from the dropdown menu and you can see that's now smoothed those numbers so we get a smooth progression from Lambda 1 through the 0.87.
07:04 In the high rpm areas in vacuum you can see that I've targeted a slightly richer Lambda.
07:14 In fact I'm going to change that to 0.95 and we're going to then, we're going to use the richer mixture in that area because we're not going to be running the engine continuously there.
07:29 That's not an area that we normally operate in and what we're doing there is we using that additional fuel we're not so worried about fuel economy here.
07:37 We're using that additional fuel because this is the area the engine is going to run through on a transient or a throttle lift when the engine is being driven hard.
07:48 We're using a slightly richer mixture to help cool and control combustion temperature in that area.
07:56 And once we've churned, once we've set some realistic targets for our Lambda aim or air/fuel mixture aim we can move on and we're going back to our Ignition table now and what I'm going to do before we start tuning is I'm going to highlight this entire table and I'm going to set the entire table to 15 degrees.
08:21 This is going to be a good, safe starting point for beginning our tune.
08:27 It's our timing and ignition advance that I know should be very, very safe and keep us away from knock when we start tuning just as an added precaution because I know that this engine at low rpm can be a little bit sensitive to knock.
08:45 What I'm going to do is further retard the timing up to 2,000 rpm between 80 and 100 kPa just so when we're at wide-open throttle at low rpm we know that the engine is going to be retarded below MBT and we can work up to we always want to start with retarded ignition timing safe retarded ignition timing that's not going to create any knock and then we can advance the timing towards MBT as we begin our tuning.
09:19 So that takes care of our Lambda target.
09:21 It takes care of our base ignition table.
09:24 We're also going to move back to our VE table and because we don't really know what the engine volumetric efficiency is going to be we can start by simply entering a VE or volumetric efficiency at 50% right across the entire table.
09:43 And that's not going to be correct but we'll see we can very quickly and easily adjust this once we get the engine running and dial-in the VE table.
09:52 We're also going to be able to quickly see the general trend or shape of that VE table begin emerging as we're tuning and we're going to be able to copy that ahead as we begin our tuning to speed up the process.