Emissions Tuning Fundamentals: 5-Gas Demonstration: Evo Haltech

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5-Gas Demonstration: Evo Haltech

16.34

00:00	We're now going to have a practical demonstration of some of the factors in our tuning that impact our emissions and we're going to be doing this on our mainline dyno using a consumer grade five gas analyser.
00:11	Specifically, the one we're using here is a QGA6000.
00:16	This is somewhere in the vicinity of about $5000 Australian, or at least that's what we paid for ours back when we purchased it.
00:25	So, this is probably something that's a bit more relatable to the average workshop owner who wants to start optimising their emissions.
00:33	Now, we've seen a demonstration earlier in the course of Mike McGinnis running some tests on SEMA's professional grade emissions testing lab.
00:42	So, I just wanted to run this demonstration, we're going to cover some of the ground he did including the effective air fuel ratio on our emissions but we're also going to look at our ignition timing and our variable valve timing, see how those three aspects play out.
00:57	Before we do this though, let's just familiarise ourself with the five gas analyser.
01:01	And we can see here while I've been talking, we've got our five gases, we've got CO, CO2, our hydrocarbons, our O2 and our NOx.
01:10	On the bottom left we've also got our lambda.
01:13	Now, just a note about the lambda here, we can see it's demonstrating or showing that we're running about 1.017, let's call it 1.02.
01:22	If we look at our link G5 ECU we can see that in fact we are actually sitting right on our target here of lambda one.
01:31	So, there is a bit of a discrepancy there, you'll note that I am also using closed loop lambda in order to make sure we maintain our lambda target.
01:38	So, a little discrepancy between the lambda numbers that the five gas is displaying and what we're seeing in our ECU.
01:44	And that's not to be unexpected, particularly with the difference in where we are picking up the lambda values, at the tailpipe with the five gas and at the bottom of the dump pipe below the turbo with our actual ECU.
01:57	We also do tend to see some differences in the calibrations between different aftermarket wideband sensors so don't take too much into that, everything else is going to still represent what we want to demonstrate.
02:09	Now, I'm going to focus for these demonstrations on just two of our gas outputs.
02:14	We'll look at our hydrocarbons and we'll look at our NOx.
02:18	Both are being displayed here in parts per million.
02:22	Before we go too far though, what I want to do is just show one test.
02:26	And this is obviously our idle here, I just want to show you the transport delay or the latency in making changes and how they are picked up by the five gas.
02:35	So, we'll just highlight the entire idle area that we're running in at the moment in our lambda target table and I'm going to change that to 0.9 and we'll press enter and now we wait for our five gas to pick up that change.
02:50	And generally I find that this takes around about 10 to 15 seconds on this particular five gas, a lot does come down to the length of the hosing running to it but we can see that that change is now taking place.
03:01	So, just important to demonstrate this and we need to understand that how we interpret our readings, we need to make sure that we allow everything to reach equilibrium and give a good amount of time for that to happen before we actually take any notice of the results.
03:17	We'll change that back to lambda one now, we'll get up and running here on the dyno and we'll start with our first test which is to vary our air fuel ratio.
03:25	Alright, we're up and running at the moment and I'm just going to allow everything to reach equilibrium.
03:29	For this test I'm going to maintain an operating point of 3000 RPM and 60 kPa which is what you can see we've got in our G5 software here.
03:38	And I have highlighted the cells surrounding our operating point just so that we're not going to be affected by any interpolation.
03:45	So, what we're going to do is actually start by setting our lambda target to 0.70.
03:50	Obviously, a very rich air fuel ratio target and probably not too far away from the sort of rich limit where we're going to start getting into a situation with misfires.
04:00	But what we're going to do is step our cells from 0.7 all the way through to lambda 1.2 in 0 .1 increments.
04:08	Let's talk about what we can expect from this test.
04:11	At 0.70 we're excessively rich so we should see quite a high level of hydrocarbons but also that excess hydrocarbons, the excess fuel passing through the combustion chamber is going to tend to cool our combustion charge temperature.
04:24	And we know that temperature is one of the factors that drives formation of NOx so we should see relatively low NOx output.
04:32	Now, we've reached equilibrium or we should be pretty close to it, let's look and we have our hydrocarbons sitting at 222, 223, let's move around a little bit, and our NOx sitting at about 130.
04:44	Ok, let's make a change here to 0.8 and again we'll just allow a little bit of time for everything to reach equilibrium.
04:52	Now, the transport delay is a little bit reduced once we're up at 3000 RPM compared to that test that we did at idle but still we can expect some delay.
05:02	Alright, so we've reached a good equilibrium here so hydrocarbons sitting at 170, 273, our NOx at around 300 parts per million.
05:10	Let's go to our next step here, 0.90.
05:13	So, again we should expect to see our hydrocarbons drop and we should see our NOx increase.
05:19	We'll just again wait for everything to reach equilibrium.
05:22	Alright, we've got equilibrium here, around about 130 on our hydrocarbons and around about 340 on our NOx.
05:29	Let's go one step further.
05:30	Alright, looks like we've reached equilibrium here with about 36 parts per million on our hydrocarbon and about 28 to 30 on our NOx.
05:39	Now, we can see here that our NOx in particular has not followed our trend, it's dramatically jumped away from the trend we were seeing where we were leaning the air fuel ratio out and our NOx value was increasing because of increased temperature.
05:53	We'll put a pin in that, we'll come back to it in a moment.
05:55	Let's make another change now, we'll go a little bit leaner to lambda 1.1 and we'll see what effect that has.
06:01	Again, let's just allow everything to reach equilibrium before we analyse our results.
06:06	Alright, so we've got ourselves to a bit of an equilibrium here, hydrocarbons sitting at about 13 parts per million, 12, still moving around a little bit and our NOx has absolutely gone through the roof here with about 3000.
06:18	So, a massive change there, let's go one step further and we'll go to 1.2 lambda.
06:24	Alright, looks like our NOx is still moving around a little bit but we're pretty close, we can see that we're actually reading, registering zero on our hydrocarbons there.
06:31	And our NOx is still incredibly high but it's dropped significantly down to about 1760.
06:39	So, let's back off and talk about our results there.
06:42	So, everything's basically aligned with what we'd expect there given that we know that the NOx is related to our combustion temperature.
06:50	From a very rich air fuel ratio, our combustion temperature is low so NOx formation should be low.
06:55	As we lean out the air fuel ratio, our combustion charge temperature increases so NOx formation will increase.
07:00	We do get to a point though, in peaks here with our little test at about lambda 1.1, we get to a point where if we continue to go leaner, we're going to actually find out our combustion charge temperature drops, our power output also drops in line with this so that's why as we go from 1 .1 lambda to 1.2, we see our NOx formation drop.
07:19	If we look at our hydrocarbon which was the other exhaust emission that we were concentrating on here, the theory here is that with a very rich air fuel ratio, we should see high levels of hydrocarbon and this should really drop away in line with our lambda target moving leaner and that did exactly what we'd expect essentially.
07:37	We can also graph these to get a visual representation of what the outputs look like and here it's very obvious to see that dip around lambda 1, particularly in our NOx.
07:49	So, why have we got this outlier at lambda 1 which sort of bucks the trend that we're seeing? Well this is simply because we are monitoring these exhaust gases, these emissions, post catalytic converter.
08:02	And we already know from the body of the course that the catalytic converter, this being a three way catalytic converter that is designed to clean up NOx emissions, is efficient and effective essentially only at and very close to lambda 1.
08:13	So, really here we're just seeing how effective that catalytic converter is at doing the job that it's designed for.
08:20	If we were to monitor these emissions pre catalytic converter or with no catalytic converter in the exhaust at all, then of course we could expect to see a more smooth and normalised linear trend to that graph but that is why we do have that outlier, just our catalytic converter doing exactly what it was designed to do.
08:41	Let's move on to our second test where we're going to monitor the same exhaust emissions relative to ignition timing.
08:48	We'll see how those emissions are affected by changes in ignition timing.
08:52	We're going to perform this test at 3000 RPM, 60 kPa, the exact same operating point we've just used.
08:58	And we're going to sweep our spark in 10 degree increments from a starting point of 10 degrees all the way through to 50 degrees.
09:06	Now, here we really shouldn't expect or wouldn't expect to see a dramatic change in our hydrocarbon output.
09:15	Essentially as long as we are achieving complete combustion, we are basically providing the same amount of fuel and air so that shouldn't really affect our hydrocarbon emissions too much.
09:26	But what we should expect to see here is an effect on our NOx output.
09:30	Now, if we're starting with a very retarded ignition timing of 10 degrees, then we're not seeing much cylinder pressure and that cylinder pressure creates heat in the combustion chamber.
09:40	So, with lower combustion chamber temperature, we should see a lower NOx output.
09:45	As we move through towards MBT and beyond, we're going to start seeing that cylinder pressure, particularly on the compression strokes, start to increase, creating more combustion temperature and hence we can expect to see a higher level of NOx.
09:58	So, let's get ourselves up and running and see how that pans out.
10:01	OK we've got ourselves up and running, I've started with 10 degrees as I explained and looking at our emissions, we've got about 22 parts per million hydrocarbons and about 10 parts per million NOx.
10:13	So, what we'll do is step up to 20 degrees and allow everything to reach equilibrium again.
10:18	Alright, not much of a change here, hydrocarbon's sitting around about 13, NOx sitting at 10, let's step up one more time to 30 and we'll allow everything to reach equilibrium.
10:28	Alright, so looking at our output at the moment, our hydrocarbon's now 10 parts per million, we are starting to see our NOx increase now, not a significant dramatic jump but up to 18 parts per million.
10:41	Let's go to 40 degrees and we'll try again.
10:46	Alright, at 40 degrees we're still sitting at 10 parts per million with our hydrocarbons, up to 40 parts per million with our NOx.
10:53	Let's go one step further to 50 degrees and see what that gives us.
10:59	Alright, so with 50 degrees we've allowed everything to settle down and our hydrocarbons actually has dropped at this point to zero.
11:06	We can see that our NOx has continued to climb a little bit following that trend that we'd expect, in fact it is still climbing a little bit at the moment but let's call that 70 and essentially that's where we've got to.
11:18	So, let's just come back to idle, we'll talk about those results.
11:21	Alright, so essentially we saw much along the lines of what we'd expect.
11:25	Looking at our hydrocarbons, we really didn't see too much change through most of the test there with the exception of our 50 degree test where it dropped to zero.
11:34	But with such low hydrocarbon output anyway, it's fair to say we're probably at or close to the resolution of this consumer grade five gas analyser so that's not unexpected.
11:44	Our NOx has essentially done what we'd expect there, started relatively low and as we advanced the timing and created more pressure and heat in the combustion chamber, we saw the NOx climb.
11:55	Nothing as dramatic as the previous test with our air fuel ratio swing but still a significant and measurable change.
12:02	It is worth noting that this entire test has been performed at lambda one target, meaning that the catalytic converter is in there doing its job and cleaning up our tailpipe emissions so the swings that we've seen here, not essentially as dramatic as what we would have seen if we had no catalytic converter or were at a richer air fuel ratio target.
12:21	With our variable valve timing test, what we're going to do is operate at the exact same point, 3000 RPM and 60 kPa, we're going to be using our closed loop control to maintain a fixed lambda target of lambda one so that the only variable we are changing is our valve timing which will affect our cylinder fill or volumetric efficiency.
12:41	We're going to swing the cam timing in 10 degree increments starting at 10 degrees and moving through to 30 degrees.
12:49	Now, what we should expect to see here is that our hydrocarbons shouldn't really change too dramatically, as long as we're getting complete combustion in essence.
12:58	But our NOx formation will be dependent on our combustion charge temperature of course and when we're starting with low cylinder fill or low volumetric efficiency, this will reduce the amount of fuel and air being combusted in the cylinder, hence we should see lower combustion temperature and lower NOx formation.
13:15	As we move to the optimal cam timing for this operating point, our cylinder fill and volumetric efficiency will increase and because we're combusting more fuel and air charge in the combustion chamber, we should expect to see an increase in our NOx formation.
13:29	So, let's get ourselves up and running and see how this checks out in the real world.
13:33	Alright, we're up and running, same operating point, we've got our 10 degree starting point for our variable valve timing, we can see our hydrocarbons and our NOx both sitting around about 10 to 15.
13:44	So, relatively low on both fronts there.
13:46	It's worth also noting here that at the moment we've got a closed loop lambda control of minus 5 % in order to get us onto our target.
13:55	We'll monitor that because this will help us understand where our volumetric efficiency is optimised.
14:01	So, we'll step up to 20 degrees now and we'll just give everything a moment for it to reach equilibrium.
14:08	Alright, we've reached equilibrium here at our starting point with 10 degrees variable valve timing on our intake cam and looking at our five gas we can see our hydrocarbons actually reading zero and our NOx reading 20 parts per million.
14:21	Also worth just taking note here of our closed loop lambda, in order to get us onto our target here, we're pulling out 4.7% fuel.
14:29	So, this will help us understand when our cam timing is optimised.
14:33	Let's step up to 20 degrees and again we'll just allow everything to stabilise before we look at our results.
14:40	Alright, with our cam timing now at 20 degrees we can see we're still reading zero parts per million hydrocarbon, our NOx stabilised maybe 35 to 38, maybe 35 to 40 so we have seen an increase in our NOx output.
14:54	We can see as well if we look at our closed loop lambda, that's now pulling out 3.6% so a percent less, it's removing less fuel meaning that it needs more fuel in the combustion chamber in order to achieve lambda one which indicates that our cylinder fill is improving, we are getting more air into the cylinder.
15:12	I'll actually just revise everything as well because while I've been talking, our NOx has still come up and it's actually now sitting at 48, 50 parts per million.
15:20	Let's move one step further and we'll try 30 degrees and allow everything to stabilise again.
15:26	OK with our third and final test point here, our hydrocarbon's still sitting at zero.
15:30	Our NOx has been moving around but it's sitting somewhere in the region of the low 50s on average, maybe 52, 53.
15:38	Looking at our closed loop lambda we can actually see now we've gone past our optimal cam timing, we're now pulling out 6.5% meaning there's now less oxygen in the cylinder, less air in the cylinder so we need less fuel in order to achieve our target air fuel ratio of lambda one.
15:56	Alright, so our third and final test complete there and a little less obvious and a little less conclusive than our other two.
16:03	Our hydrocarbons obviously didn't really do anything, sitting at zero through that test, our NOx did for the most part do or track in line with our expectations.
16:12	But essentially I just want the takeaway from this particular test to be that every parameter that we have the ability to change within our tuning software can and will affect our tailpipe emissions.
16:24	Hopefully these demonstrations have helped reinforce the topics taught within the body of the course.