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Practical Standalone Tuning: Step 7: Steady State Fuel Tuning

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Step 7: Steady State Fuel Tuning

21.29

00:00 - OK so now that we've got the engine idling properly, we know everything's OK, it's time to actually start running the car on the dyno and doing some tuning.
00:09 Now we're going to split this up into two different sections and we're going to deal with the fuel side of things first.
00:14 Basically the ignition timing that we've got in there, we know that should be safe, and it should be pretty conservative.
00:23 So particularly when you're just starting out, it can be really quite daunting trying to do the fuel and ignition timing together.
00:31 Once you get a little bit more confident, and a little bit more experience, you can easily swap between the fuel and ignition tables.
00:38 And you'll tend to tune both of them simultaneously.
00:41 For now just to make it really easy, we're just going to deal with the fuel side of things.
00:46 So if we look at our fuel table here, we've got our fuel mixture aim which we've already set up.
00:54 We've got our volumetric efficiency table, and I've got our special worksheet that I've set up with our fuel mixture aim and our exhaust lambda.
01:02 So for this particular part of the course, we're not actually going to worry about looking at the dyno screen, we're just going to be concentrating on what's happening on the laptop.
01:12 So what we wanna do is we want to start with as little load as possible, and as low in the RPM as we possibly can.
01:20 So we're going to start with 1500 RPM.
01:23 So we'll just start the engine running on the dyno.
01:25 And what I'm doing now is we're up to 1500 RPM, and I can just remove the throttle slowly and surely and see how far down in the table I can get.
01:38 Now I'll just show you, if I drop the throttle down too far, at some point what will happen is that the engine will actually just slow down.
01:48 The dyno requires a certain amount of torque to keep it spinning.
01:52 So you can see here we're actually just starting to drift down to 1250 RPM.
01:57 So basically the 50 kPa row, it's about as low as I'm going to get here.
02:03 And this is really important, this little target that we've got here.
02:07 That shows us how close to the centre of the row we are.
02:11 Now it's time to actually make some adjustments to our fuelling.
02:16 Now there's a few different ways we can do it, and the way that you choose will depend on how far out the mixture is, how comfortable you are with the software, and how quick you are as well.
02:27 There's no right or wrong way.
02:29 You basically need to figure out for yourself, which works best for you.
02:34 So for a start what I'm going to do is show you how you can just directly enter numbers into the table.
02:39 So I'll bring it up to the 60 kPa row where I know that I can be centre on the target.
02:46 And you can see that we're running at lambda 1.08 and our aim is lambda one.
02:53 OK so the first way we could make an adjustment to that particular number is we could just enter it.
02:57 So let's enter 52 and see how we get on.
03:02 So you can see it's gone slightly richer, but it hasn't really made much of a change.
03:07 We could go maybe 58, let's see how that works.
03:10 You can see we've gone quite rich.
03:13 Maybe we could try 55.
03:15 OK look we're right on the money there, we're bang on where we wanna be.
03:19 OK so that's kind of what I'd like to call the trial and error method, and there's nothing wrong with that to be honest, that's how 90% of tuners get the job done.
03:27 It is quite slow though and there's a much quicker way of doing the tuning changes.
03:34 So now we've tuned this zone here at 55 and what we wanna do is increase our load, get up into this 70 kPa row.
03:44 But before we do that we're going to copy the 55% VE that we've got in the 60 kPa load zone, and we're going to enter that into the 70 kPa zone.
03:54 'Cause we know there's a pretty good chance that the volumetric efficiency's going to be at least 55 if not higher.
04:01 Now I'll increase the throttle position and you can see we're now centred on that site and you can see we are very close.
04:09 We're running at lambda 1.02 What that means is we're around about 2% lean.
04:14 So we can use our calculator, and I'll just bring up the calculator and show you that.
04:20 And I'll show you how we could calculate a correction factor to enter in here.
04:27 So we use our have over want.
04:29 So we have a lambda of 1.02 and we divide that by what we want which is lambda one.
04:35 That gives us a correction factor of 1.02 Basically we're adding 2% to that particular zone.
04:42 So if we take that 1.02, we enter it here, so 1.02, if we hold down the shift key and press the asterisk, that will multiply the number by 1.02 And you can straight away see, bang we're right on our target.
04:58 So that's how we can use the have over want function.
05:01 Once you get a little bit more familiar with tuning like this, particularly if you're using lambda, you actually tend to look at the difference in lambda and that basically gives you a really good guide as to the percentage change to make.
05:14 So let's take our 56% that we've got there, copy that into the 80 kPa row, we'll increase our load.
05:23 So again we're running at that 1.02, almost 1.03 lambda.
05:29 So we're about 3% lean.
05:32 So what we're going to do is we're going to just make a guess based on that.
05:37 We know 1.02, 1.03, 2% to 3% lean, so we're going to multiply that particular value by 1.03 Again straight away we can see we're on our target.
05:48 So that's how we do it without the calculator.
05:51 This is one of the reasons why you should be using lambda to tune.
05:55 OK the third way is to allow the Motec to actually do the hard work for us.
05:59 Motec have a function called quick lambda.
06:02 And what that does is you basically go to a particular site you want to tune, make sure you're centred on that zone, and the Motec will do that have over want for you.
06:13 So does all that calculation and applies the correction directly.
06:16 So we'll do this in our 100 kPa zone.
06:19 So before we do that we're gonna copy our 57.7 from the 80 kPa row.
06:25 And we'll copy that up to the 100 kPa row.
06:29 So now I'm gonna go to full throttle.
06:32 OK so you can see our target lambda has dropped to our 0.90 Now we're running around about 6% to 7% lean.
06:40 So if I just press the Q key, that will make that change for us, and you can see straight away we're just about on target.
06:50 It's actually a little bit lean still, not very much, maybe 1%.
06:54 So again we could press the Q key again and it'll just make a further adjustment based on any remaining error.
07:00 Or we can just use the page up to make a small manual change.
07:05 OK so that basically covers the tuning of the 1500 RPM row.
07:10 But before we move on, I just want to show you a little trick we can use to get a little bit lower in the load because we've only been able to access the ECU properly from around about 60 kPa and above.
07:23 Now when we're cruising down the road, only just touching the throttle, we're likely to be more down in this 50, 40, or even 30 kPa area.
07:32 So basically what that means is we've got a large chunk of the map that currently we haven't actually been able to access and we haven't been able to tune.
07:40 Now the dyno works, it requires a certain amount of torque to keep it running as I've mentioned.
07:46 What we're doing at the moment, we're tuning the car in fourth gear.
07:49 So what I could do is I can actually run the car in first gear and that basically multiplies the torque through a shorter gear and basically we're going to end up producing more torque for the same engine torque at the axles.
08:04 And this will allow us to drop the throttle a little bit further and we'll be able to access some of those lower areas.
08:11 So just going to do that now and I'll show you how it works.
08:16 OK so we've now got the engine running in first gear.
08:20 And we just need to recalculate our RPM so that we can get that down to where we want.
08:28 So I'm just bringing the dyno RPM down now.
08:32 And you can see we're moving down into that 1500 RPM row.
08:41 We'll just keep going, so now we're centred pretty accurately on that 1500 RPM row and you can see now I'm actually down in the 40 kPa area.
08:51 So we're accessing well down in the mapping area, we couldn't get to before.
08:55 So I'm just going to press the Q key for quick lambda and you can see that that's correcting our error and we're now idling pretty closely at lambda one.
09:09 We haven't done the 50 kPa area, so I'm just going to increase the throttle a little bit.
09:16 Now we're about 3% lean there.
09:20 So I'm going to enter 1.03 and multiply.
09:25 That's going to correct most of our error, we're still a little bit lean so you could just manually fix that.
09:32 And we'll see how far we can get down in the load just by taking my foot off the throttle.
09:38 And you can see we can only get down to that 40 kPa area.
09:44 So that's filled out a little bit more of the map and that's a trick that we definitely want to use.
09:48 We wanna basically fill out as much of the map as we can on the dyno.
09:53 Now what I'm going to do before we carry on, you can see we got down to 40 kPa and we've got a number of 47.3 in there.
10:00 Below this, these are the areas we couldn't get to and we're still at 50% VE in there.
10:05 So I'm just going to manually set those to 47.3% at the moment.
10:13 There's a pretty good chance just based on the way the engine operates, that the VE will be lower than 47.3 That just gives us a pretty good starting point.
10:22 That basically completes the tuning of the 1500 RPM row.
10:26 Now what I'm going to do is I'm going to highlight that whole column, I'm just gonna press control c to copy it.
10:32 Gonna move across to the 2000 RPM row.
10:35 And I'm just gonna press control v, and that will copy those numbers into the 2000 RPM row.
10:41 Now the reason we're doing that is we're trying to make our job easier.
10:45 We know that the VE numbers at 2000 RPM are probably going to be at least as high as at 1500 RPM if not higher.
10:53 So the next step we're going to do is we're gonna highlight that whole row and we're gonna multiply it by 1.05 to give us 5% additional volumetric efficiency.
11:03 So now that we've done that, we're just going to increase the RPM on the dyno to 2000.
11:12 And we're going to run the car again and basically repeat the process.
11:21 So again we can only get down to 60 kPa.
11:26 Now before I make any changes, what I'll do if everything's equal, basically if one cell at 2000 RPM is a little lean or a little rich, then chances are that whole row will also be a little lean or a little rich.
11:42 So what I'm going to do is highlight that whole row and apply an across the board change before I look at the individual sites.
11:50 Now looking at our lambda, we're actually really close.
11:53 I was just about 1% too lean on that.
11:59 So we almost could leave it alone, I'm just gonna multiply the whole row by 1% And then we're going to drop back and we're going to have a look at our individual sites.
12:10 So we'll drop back to 50 kPa and you can see we're right on our target.
12:13 So we increase the load, and we come up to 60 kPa, and again we're right on our target.
12:24 70 kPa.
12:28 Again just about perfect there, we'll go up to 80 kPa and you can see at 80 kPa we're a little bit rich, we're running at about 0.98.
12:38 So we're about 2% rich so I'm going to multiply that particular number by 0.98 just to correct that back, I'll just make a small manual change there as well.
12:50 And we're close to where we wanna be.
12:54 And we'll go to full throttle and we're already absolutely perfect there.
12:59 So that's the 2000 RPM row.
13:02 So basically what we wanna do is just rinse and repeat basically copy the procedure through the rest of the map and we're going to do this up to 5000 RPM.
13:12 Above that we don't need to be quite so precise because the engine is not going to be sitting there at constant speed.
13:19 So just watch as I complete the rest of this map and you can see exactly what I do.
13:24 We'll start by just copying that 2000 RPM row across to 2500 RPM and we'll do the same procedure of multiplying it by 1.05% to increase the VE.
18:53 So once we've tuned the engine up to about 5000 RPM, beyond that the accuracy isn't quite so important as I said, we're not gonna be sitting in those areas.
19:03 So what I'll do at this stage is basically copy the row that I had at 5000 RPM and copy that across to the remainder of the map.
19:14 Now we're still going to be looking at those numbers when we do the full throttle tune.
19:20 What can be useful though is to just go through and have a quick look and make sure that the numbers aren't too rich or aren't too lean.
19:29 Generally in this area I'd be erring on the side of being a little bit richer rather than a little bit leaner and what we can do is just choose the entire row, highlight the entire row, go into it on the dyno and just make an across the board change to the entire row.
19:48 So I'll show you that now.
21:06 So you can see that in those particular areas, I can actually really quickly dial in the entire row, make sure that it's close enough and it's not gonna put too much stress on the engine because it's not running in those areas for very long.