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Practical Standalone Tuning: Step 3: Base Table Configuration

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Step 3: Base Table Configuration

12.45

00:00 - So our next step is to configure the base fuel and ignition tables so we've got all of our axes set up, our inputs for our load are all set up and everything's ready to go so we can start tuning.
00:13 Now you've already seen me work through this in the main body of the course but I'm going to just explain it again and go through it in a little bit more detail.
00:21 So if we start by going to our engine details page here, this is where we can set up what the input for the load axes are.
00:31 Now MoTeC, the same as they've done it on their 100 series, they have two terms, one is called efficiency.
00:38 Now basically efficiency in MoTeC lingo is the load axis for the fuel table.
00:43 So if we go to efficiency we've got our mode and basically the options we've got there is manifold air density or ambient air density.
00:53 We're using a standard manifold pressure sensor so we want to leave that set to manifold air density.
01:01 Now for the ignition table, we can have a different load axis and in MoTeC lingo, that's called load as opposed to efficiency.
01:11 And in the M150 it's actually engine load normalised so we've got our options here, we can have inlet manifold pressure, basically manifold air pressure, or throttle position.
01:22 And we're just going to leave that on inlet manifold pressure.
01:26 So that makes sure that we know our tables are set up with the right load axis, that's the first step.
01:32 Now we can actually swap back through to the tuning workbook and we can go between the ignition and the fuel tables.
01:41 So what we're looking at with the fuel table is our engine efficiency table.
01:46 If we press F6, that'll maximise that and we can move around the table.
01:50 I said one of the most common problems I see or common mistakes I see people making is trying to add way too many zones into a table.
01:59 The ECU, even a basic one will interpolate between the surrounding zones so we don't actually have to have the engine set up with a million zones.
02:08 All that's going to do is make our job more difficult and more time consuming as we fill in the table and what's going to happen basically if we have less zone's, the ECU's just going to do all of that work in the background so my advice is don't make your job any more difficult than you need to.
02:24 There will be occasions, and we're going to see this a little bit later on, where we will want to add a zone maybe into the table and we can easily do that later, it's not a big deal and we don't have to retune the table just because we've added a zone.
02:38 So in the MoTeC, if we press the A key while we're on one of the tables, you'll see we get an axis setup menu come up.
02:45 Now what I'm going to do there is just generate a new table and we're going to make it pretty basic so for the engine speed axis we're going to go between zero and 8000 RPM and I'm just going to start with increments of 500 RPM.
03:00 So that'll set up up with a nice easy fuel table.
03:04 Because I'm going to expect this engine to idle at around about 750 RPM, sometimes it can be handy just to have down at idle, an RPM zone that is right on our target idle speed so we can make some really accurate changes to the fuelling there.
03:21 So I'm just going to add another one in at 750 RPM and oops we've actually just removed the zero so I'll just add that back in.
03:30 So now we've got 500, 750 and 1000.
03:33 Quite possibly we also might want to add another zone in at 1250 RPM.
03:38 That'll just give us a little bit more control just as we come off idle and quite often that can be a fiddly area that we want to spend a little bit of time getting really right.
03:49 And that'll allow us to do that.
03:51 So that's the RPM axis that I'll start with.
03:54 Now let's have a look at the inlet manifold pressure.
03:57 Now again we've got a base table there that's got zones everywhere and we're just going to start again.
04:03 We're going to go between zero and 100 kPa, 'cause this is a naturally aspirated engine, and we're going to start with zones every 20 kPa.
04:12 That's going to give us a reasonably broad map, you can see we've got six zones here and that's not a heap of points that we need to tune.
04:21 Again, the engine's going to spend the majority of its time cruising and we want to be able to make sure that our mixtures in our air/fuel ratio control there are really accurate so quite often I will then add in slightly tighter zoning around those cruise areas.
04:39 Chances are though we're not going to know exactly where those cruise areas are until we've actually got the engine running and we see how much vacuum the engine pulls in cruise and that's going to depend on the engine capacity, the number of cylinders, camshaft timing, compression ratio and a number of other features so again, don't get too hung up on it now, it's really easy to change this later if we need to.
05:03 At a guess, what I'm going to do is I'm going to add a zone in there at 30 kPa and I'm going to add another one in at 50 kPa.
05:12 If in the midst of tuning the engine, you do find that it's a really dramatic change in VE across quite a tight manifold pressure range, it's really easy again, maybe you want to add another zone in at 70 kPa, all you have to do is go like that, add it in and you're away.
05:32 So it's really easy to set this up.
05:34 So once we've done that, we can just press OK and the ECU is just going to automatically fill in that table and interpolate any results that weren't there.
05:46 So that's how we do that with the fuel table, we'll now swap over to the ignition table and we'll basically go through the same procedure.
05:53 Now if we press the A key in the ignition table, again we're going to generate a new engine speed table and as I said in the main body of the course, we don't need to be so accurate with our ignition numbers because the engine's performance is not quite so sensitive to changes in ignition timing.
06:13 So generally 500 RPM increments in the ignition map are totally fine.
06:18 If we go through to the engine load normalise table, again we know from our setup that this axis is also manifold pressure and we're going to generate that table as well.
06:30 Again we can just go between zero and 100 with 20 kPa increments.
06:35 If for some reason you decide that you need to add some more zones or you want more zones for whatever reason, again easy to add these in if you want.
06:44 In my experience, except for anything that's tuned on throttle position or alpha-N, 20 kPa is generally pretty much OK for most engines.
06:54 So we're going to press OK and again that will automatically generate the table and interpolate all of the results.
07:02 So all that remains now is to get some numbers into that table that we know are going to be a reasonable starting point, so all I'm going to do is highlight the entire ignition map and we'll just enter 15° everywhere and I know that's going to probably be a pretty safe starting point for most engines.
07:20 Unless you've got a very high compression ratio or you're running on very very low grade fuel, 15° shouldn't be a problem with detonation.
07:28 As I've said though, when you're tuning any engine, always use quality knock detection gear so you can pick up any detonation immediately and back off before you cause any damage.
07:40 We'll just swing back to the fuel table and we're going to enter some numbers in there that'll get us running as well.
07:49 Now again this is a proper VE based fuel model so as long as our fuel table is, sorry our injector information is correctly entered, this is a table of proper volumetric efficiency and generally somewhere around about 40 to 60% VE is about what you'll find with most engines at idle.
08:11 So what we're going to do is just enter a number of 50 everywhere in the table and that'll just flatline the table, should be enough to get us up and running and we can quickly change that once we've got the engine running.
08:24 One more part with the MoTeC M150 because it is a VE based fuel model, we do need to enter in our fuel mixture aim table.
08:35 Now I've still got this set up from before, but we're just going to zero it out and set it all to lambda one and we'll talk through how we can change that.
08:45 So the VE based fuel model is always using this mixture aim table to try and achieve the correct air/fuel ratio.
08:56 So it's important that we firstly set this to the lambda numbers that we actually want to achieve and secondly once we've done that, it's important when we're tuning the engine which we'll look at soon, that we actually adjust the volumetric efficiency table until we're achieving these aim lambda numbers.
09:13 OK so what I'm going to do is first of all we've set everything here is at lambda one and that's going to be where I'm going to run the engine for the idle areas and all of the cruise.
09:27 And that's going to give me good fuel economy which is really important.
09:31 When we get up to wide open throttle though we don't want to be running at lambda one, we're going to need to add some fuel.
09:37 Now that extra fuel's going to help control combustion temperature.
09:41 It's also going to make sure that we're using up all of the available oxygen and we're getting maximum power.
09:47 Now you can see this particular table is spanned all the way out to 110 kPa so that should go slightly into positive pressure.
09:54 So what I'm going to do is I'm going to highlight the 100 and 110 kPa rows and out to 5000 RPM I'm going to target 0.90 lambda.
10:07 Now I know from my own experience with a low powered naturally aspirated engine, that's going to be a pretty safe bet that that's where the engine's going to make good power.
10:17 Now this particular engine's also fitted with a catalytic converter in the exhaust and what we'll do is we're going to run the engine a little bit richer as we go up in the RPM and get closer to engine redline and that extra fuel's going to help keep the combustion charge cool and it's going to control the exhaust temperature and that's going to protect our catalytic converter.
10:39 So what I'm going to do is at 8000 RPM, so it's just a little bit past our engine red line, I'm going to target 0.87 lambda.
10:49 I'm just going to use the interpolate function in the M150 and I'm going to press i and that's going to interpolate between 0.90 at 5000 and 0.87 at 8000 RPM.
11:02 OK so now what we need to do is get some smooth sort of transition between our cruise lambda one and our target 0.90 at wide open throttle.
11:14 And basically I'm going to allow it to target lambda one up to 80 kPa.
11:18 So we'll just highlight that 80 kPa row there and out to 5000 RPM again and again we're just going to interpolate between lambda one in that 100 kPa row at 0.9, press the i key and that fills that in for us.
11:37 Now above 5000 RPM, I'm actually going to target slightly richer than lambda one, even in the cruise areas.
11:46 Now we'll just highlight this area here that you can see.
11:49 I'm going to set that to 0.95 lambda.
11:52 And again I'm just going to use the interpolate function here to just fill in the rest of the table.
12:02 Now the reason I'm going slightly richer in this high RPM low vacuum area is it's not an area we're going to be cruising in so we're not so worried about fuel economy.
12:12 That's an area we may access when the car's in overrun, maybe being driven hard on a racetrack or something like that and the driver's just coming out of the throttle.
12:22 So we're not really too worried about power, we're really not worried about fuel economy, I'm just going to add a little bit of extra fuel in there to help control combustion temperature and keep that exhaust temperature down.