Practical Standalone Tuning: Step 6: Idle Tuning

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Step 6: Idle Tuning

12.40

00:00	The next step of our process is really a bit of a continuation of our last step where we got the engine running for the first time.
00:06	And again this is another one that's often overlooked and it's really worth putting some effort into this step before we actually get near the dyno.
00:14	And yes I know at this stage we already have our car on the dyno, but in a typical tuning session I would be at the end of this stage before, or step I should say, before I ever considered putting the car on the dyno.
00:25	And the reason for this is up until the end of this step we're really going through a bit of a configuration and fault finding exercise.
00:31	And we're making sure to the best of our ability that when we hit the dyno, everything's going to work as planned, we don't have any mechanical issues with the engine and this should ensure that our tuning session goes as well as possible.
00:44	This avoids the number of cars that I saw go onto a dyno only to find that maybe the alternator wasn't charging or there was an issue with cam timing or another mechanical issue with the engine that just wastes time and obviously dyno time is expensive.
01:00	So, what we're going to do here is spend some time getting our idle settings dialled in to make sure that we can get the engine to idle at what I'd consider to be a sensible RPM and with sensible manifold vacuum.
01:13	The reason we're doing this is because if our cam timing is out or maybe there's an intake manifold leak or something of that nature, we'll really struggle to get the engine to idle properly and if that's the case, all of our tuning above idle is just going to be wasted because once we've fixed the actual core issue, we're going to have to come back and redo all of our work.
01:34	This also comes down to a degree to having a bit of an understanding of what we should be able to expect and what I mean by this is with a stock 4G63 Evo9 like this, with stock cams, it's pretty typical that we should be able to make the engine idle at maybe 750 to 850 RPM.
01:50	If we can't, this could again be indicative of an issue.
01:55	Flipside of this though is if we've put in a set of very aggressive cams with a lot of overlap, a lot of duration, a lot of lift, under these conditions we may need to raise the idle speed target to maybe 1000, 1100, even 1200 RPM, my drag car would not idle below about 1700 RPM.
02:13	So, we do need to choose an idle target that is going to be reasonably well matched to the mechanical configuration of the car.
02:21	The other aspect that goes hand in hand with making the engine idle is the amount of manifold vacuum that we're pulling and again this should be something that matches the configuration of the engine.
02:30	If we're struggling to pull more than maybe 10 or 15 kPa of negative pressure at idle, again with stock cams, something is not right there.
02:40	Another issue we want to look at is just to make sure that our alternator is charging.
02:44	This is a surprisingly common mistake that people make or a surprisingly common issue I come across and if our alternator is not charging then our battery voltage isn't going to be where it should be and this kind of has a knock on effect on most of our tune.
02:59	Alright, enough talk, let's jump back into our software and have a look at what's going on here.
03:04	So, while I've been talking, you can see that at the moment now that we are up to operating temperature, we are a little bit rich and let's just start by correcting that.
03:11	So, we'll use the shift and A key and just pull our fuelling back down until we're at least in the ballpark and it looks like we're actually pretty close with our 50% guess, I'm just going to actually pull a little bit out of this.
03:24	Again I don't need to be too fussy with my actual tuning right now.
03:28	Lambda one, we're pretty much right there with values of 48% and we can see that obviously we've got all four cells that we're kind of interpolating through here at the moment set to 48%, that's not necessarily going to be realistic once we've started to actually tune these cells, but for now that's absolutely fine.
03:47	Let's just have a quick look at our runtime values and we'll pull those up by pressing the R key and if we come across to general, let's find that, we will be able to see all of our general inputs and what I want to look at here is our battery voltage.
04:03	We can also display this numerically as a value on our screen anyway, but we just want to make sure, that our battery voltage is sitting somewhere around about 13.8 to 14.2 volts and we can see that it is.
04:15	We can also just give the throttle a quick blip and bring the RPM up a little bit.
04:20	And we can see, yep, our battery voltage is staying nice and stable.
04:23	So, happy with our alternator doing its job, that is charging.
04:28	Let's have a quick look at some of our idle settings.
04:30	Now, I know I'm pretty comfortable with this at the moment because I'm going to be targeting around about 850 RPM.
04:36	You can see our throttle position currently zero, so I'm completely off the throttle and we are idling by ourselves, but we'll press the escape key and what we'll do is come down to our idle speed control and our idle speed control setup.
04:48	Now, a couple of things, I'm not going too deep into our idle speed setup within the worked example.
04:54	Again we do cover idle speed control setup in our members webinar, so if you want a detailed look, at that in a webinar that runs for a full hour, that's the place to go.
05:04	We'll cover some of the basics though, first of all during this particular setup we will run with our idle ignition control off.
05:11	Idle ignition control essentially uses changes in ignition timing to affect our idle speed control as kind of a very fast and accurate way to adjust our idle speed.
05:22	Problem with this is as part of this step we will be coming back and readdressing our base ignition timing and I don't want anything affecting our ignition timing, albeit when we are in base timing mode it will override this, but for now for simplicity and, so I'm not chasing idle settings that are being affected by our ignition timing, we're going to leave it off.
05:43	Likewise our mode of operation, at the moment we're in closed loop.
05:47	And what this means is it's going to be correcting for any errors.
05:51	This can be misleading because at the moment everything looks like we're idling quite nicely, we are sitting around about 900 RPM at the moment and this might be correct or it might be just the idle speed control doing its job.
06:03	Let's just press escape for a moment and we will come down to our idle target RPM table and just check what we've got in here.
06:10	Now, we can see that we are targeting 900 RPM which is exactly where we're at.
06:15	And we can probably drop that down a little bit, let's just drop that down for the sake of making a change to 850 RPM, we'll press F4 and because we are in closed loop mode we can see that the idle speed drops to match our new target.
06:28	OK, let's see how close we actually are though once we disable our closed loop mode.
06:35	So, we'll use the back arrow there and we will go momentarily into open loop.
06:41	OK, so the idle speed has just dropped dramatically, we're now down to about 650, 700 RPM.
06:46	So, what this indicates is that the base idle stepper setting is incorrect, that's OK we'll adjust that in a minute.
06:54	But just as importantly what we can see is that the engine is actually still idling really happily.
06:59	Sitting at about 700 RPM, we've got about 37 kPa manifold absolute pressure.
07:05	So, again mechanically we're ticking the box there, everything is obviously quite clearly OK.
07:11	What we will do though is just see how we can change our base position.
07:16	So, we'll click on our idle base position table.
07:19	And what we're gonna do here, we've got a two dimensional table of course relative to our engine coolant temperature.
07:24	At this stage we can just choose to make adjustments to our up to temperature operating range.
07:31	So, I'll just highlight from 70° up and essentially by using the shift and Q key, we can add percentage to this and as I do this, we should see our idle speed increase.
07:44	And this is coming up very slowly, so we'll just keep going here.
07:49	Let's give the throttle a little bit of a blip here.
07:51	And we're up to 750 RPM, but it's actually doing very little.
07:56	We're up to 800 RPM now.
07:57	So, it looks like our whole table is probably quite a way out.
08:01	We're up to 850, 870, yeah OK, so it is actually working, just that first maybe 10% of changes that I made really didn't appear to have much effect.
08:10	So, we'll come back down, we've changed our target to 850 RPM.
08:14	So, 43.5% is giving us our target idle speed.
08:18	Just as importantly, it does show that the idle speed control system is working.
08:23	When I make a change to this, it is actually affecting the idle speed.
08:26	What we've got now is a bit of a disconnect here.
08:29	I obviously only made those changes from 70° and above.
08:33	It's not really relevant because we are going to need to come back and address our cold start and our idle speed from cold once we've got the whole of our fuel and our ignition table tuned.
08:44	But for now you can see there's definitely going to be some problems here because if we look at what happens from 20°, 45%, then we're 40%, then we drop all the way down to 29.4% at 60° which just looking at what we need at 70, 80 and 90, I know that's not going to be right.
09:02	You could put a bit of a bandaid on this for the moment if you feel the need, and we could use the shift and H key to horizontally interpolate.
09:11	This won't be right, but at least gives us a table that probably has a more realistic set of numbers in it, we can look at that graphically.
09:19	But for now we're happy with what's going on.
09:21	We can choose to convert back to our closed loop mode at this stage.
09:26	So, we'll go back to our idle speed control settings and we'll change to closed loop.
09:32	And we do not want to set all of our tables here to zero, so we'll just run with what we've got and we'll press F4 to store that change.
09:40	And once we've gone through and we're happy with everything, we've set our base ignition timing again with the engine now running and I would do this, as I mentioned, about 1500 to 2000 RPM.
09:50	We can also set our ignition delay and make sure that's correct.
09:55	And once I'm happy with everything, I would also choose to set up our idle ignition control.
10:00	Now, with our idle ignition control there are also some other parameters here.
10:04	So, we'll press escape and come to our idle ignition control parameters.
10:08	So, we've got a single target mode here.
10:10	We are targeting 10° at idle.
10:13	So, what we want to do is target an ignition timing value that we can both retard and advance the timing to achieve an increase and a decrease in torque.
10:22	As that torque change as we advance and retard the timing, that changes our idle speed.
10:27	We've got a maximum clamp of 30°, that's possibly a little aggressive.
10:32	We could set that to 25°.
10:34	Our minimum clamp there is 0°, that's probably about as far as I'd want to go here.
10:39	If we retard the timing too far, and basically this would be in response to our base stepper position being too high, we can end up with the timing in the negatives and what that can do is create a lot of unnecessary engine bay heat in the exhaust manifold and turbocharger at idle.
10:55	So, I don't really like to see the timing go down below zero.
10:59	And then we've also got some adjustments here if required for our proportional and derivative gain.
11:04	I've actually found that the default values here typically are pretty good.
11:09	If you wanted you could bring this ignition idle target up to more like about 15°, that's still going to give us a really good range to both advance and retard.
11:20	Now, if we come across to the ignition table, we can see now we've got this gauge here that shows what our actual ignition timing is doing.
11:28	And it's actually not doing much which generally means that the idle base position is pretty close.
11:33	But what we can see here is that the value in the cell that we're accessing at the moment is 15° and we can see, if we look at that gauge again, it's sitting pretty much on 15° which we also know was the target I just set.
11:45	But it is moving up and down a little bit.
11:47	What we can start to see if we've got much greater error between our target idle speed and our measured RPM is that ignition timing's going to advance and retard quite quickly.
11:58	So, it's a very quick way of making changes to our ignition timing, whereas the idle stepper is a bit of a slower way.
12:05	And what will happen is that the stepper will basically play catch up until we get that ignition timing back into our target range around 15° which is exactly where we are now.
12:15	So, at this point we've got our engine idling quite comfortably.
12:18	We know that we're idling at a sensible RPM and manifold absolute pressure and we know that our idle speed control circuit is doing what it should be doing.
12:27	We also know we've got good battery voltage, there's no mechanical issues with this engine.
12:31	So, we're actually ready to load this car onto the dyno now and actually begin our dyno tuning session.