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Practical Standalone Tuning: Step 6: Idle Tuning

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Step 6: Idle Tuning


00:00 - Alright now that we've got our engine initially up and running for the first time, we're going to move on and the next step of the process is to spend a little bit of time and just ensure that we can get the engine to idle properly.
00:10 It's very tempting at this stage now that we've actually got the engine up and running, to jump straight into the tuning process and this can catch you out, particularly if you find there's some mechanical issues such as cam timing for example that could end up wasting a bunch of your time and these can be picked up usually reasonably easily with the engine sitting here at idle.
00:33 So what we're looking for here is some indications that there are some issues with the way the engine's running.
00:40 Key element here is our manifold absolute pressure and the ability of the engine to actually maintain a sensible idle speed.
00:48 What is sensible idle speed mean, well that does depend a little bit on your application, a little bit of common sense and sometimes some experience can help here.
00:56 What I mean by this is that for a completely standard EJ20 like this with stock cams, we could rightly expect that it should be able to idle pretty comfortably at or around the factory idle speed so I would imagine that if I can't get the engine to idle stably between maybe 750 and 950 RPM, something's wrong.
01:19 So if you've got an engine that's sort of hunting, oscillating and stalling at those sort of target idle speeds, that's indicative that there is a problem and that'll normally go hand in hand with the manifold vacuum not being as much as we'd expect.
01:33 So let's have a quick look at this.
01:35 So we can see at the moment, we're still kind of left off from where we were.
01:40 We're sitting at -60 kPa and 750 RPM.
01:44 The engine is absolutely stable, we can see that our engine coolant temperature has come up now, we're sort of in a position where the fans are sort of starting to cycle in and out.
01:53 And if we look at our air/fuel ratio over on our dyno, we can see that we are probably still a little bit richer than we actually need to be.
02:02 Now at this point I am going to start getting a little bit more fussy with my tuning so what I'll do is just start to dial that in a little bit and we can do that just by using the shift and A key and we can see that our target lambda at this point from that air/fuel ratio target table that we already filled out, 0.96, we're at 0.94 so we can take another percent out probably will get us there or there abouts.
02:28 Again once we actually start tuning we're probably going to have a little bit more work to do but yeah that looks like it's got us where we need to be.
02:35 Now looking at our manifold vacuum, -60 kPa, that's about what I'd expect, our manifold pressure is about where I'd expect for a healthy engine so no real issues there.
02:46 Maybe a little on the light side, maybe -65 kPa would be probably closer to the mark but again we're at least in the ballpark.
02:53 If you've got a real issue with cam timing, you're probably going to find that you're going to struggle to pull any reasonably vacuum so you're probably going to be closer to maybe zero to maybe -20 kPa.
03:04 So again that checks out.
03:06 The other element that is worth checking at this stage is our battery voltage and the reason that this is important to check is that again particularly for a freshly built car or something that's been wired up, it's quite possible, the number of times I've seen it is quite remarkable, that the alternator is not charging.
03:24 Now this is easy to overlook, particularly at the start where you've got a properly charged battery, you'll be able to get the engine up and running but if the alternator's not charging, you're not going to get full fuel flow from that fuel pump, your ignition system's not going to have proper ignition energy and over a very short period of time you're going to find that that battery voltage is going to drop and essentially you're going to be wasting a bunch of time so what we can do here is press R and if we cycle through to the general tab, we can see here we've got our battery voltage being displayed and we can see that that's sitting at about 14.2 volts which is about where we want it to be.
04:04 Generally, I say 14 volts but generally it's going to be somewhere between 13.8 and 14.2 volts.
04:09 So at the moment, everything is looking right on point and I'm pretty happy with that.
04:14 Before we move on, I will just have a quick look at some of the idle speed control settings and I'm not going to get too in detail with this but it is worth making sure that we can control that idle speed.
04:25 So let's press the escape key and what we're going to do is come down to our idle speed control settings which is here and let's start with our idle speed setup.
04:37 So for a start, we've got idle ignition control which is our first setting and this uses ignition timing to help with our idle speed control.
04:45 I am a big fan of that but this does come secondary to getting our base idle speed control settings dialled in for a start.
04:54 So we'll leave that off for the moment.
04:55 We've got our more which is closed loop.
04:57 While I'm setting this up I actually want to go to open loop and the reason I do this is that this way the closed loop control system is not going to be basically fixing any errors that exist so we'll turn that off.
05:10 The actuator type, again this is by default for this base map, correct solenoid but we can obviously double click on that and adjust this to suit.
05:19 We can use voltage compensation which is off, I'm not going to use that.
05:23 The actual output that is being used, again I'm not going to get too much more into detail with these things.
05:29 We do need to keep in mind here, we've got some lockouts for speed, for accelerator or throttle position, in this case 1%.
05:37 We can see that that's sitting at 0.3 so we want to make sure that the idle speed control system is only working when we actually want it to.
05:44 I'm actually going to drop that a little bit to 0.5%.
05:47 Now we do also have an RPM lockout here.
05:50 We can see that's set to 600.
05:52 Now this is actually 600 above our RPM target.
05:55 So essentially if our RPM's above that, the idle speed control system won't function.
05:59 Likewise if our manifold absolute pressure is above 50 kPa, it won't function so we can see that our current manifold absolute pressure, sitting at about 36, 37 kPa so we're within the realms there, just important to check these things to make sure that there isn't actually a lock out that's active that is stopping the idle control circuit from working.
06:19 Alright we'll press escape here and what we're going to do is come up to our idle base position table here.
06:27 Now this is a 2D table, it is relative to our engine coolant temperature and this is just simply the duty cycle being delivered to the idle speed control soleoid so what we can see is that we've got this yellow box showing us where abouts we're currently operating.
06:42 Obviously we are sitting at 94° at the moment so we're between zones.
06:46 We can see the general trend here that when the engine coolant temperature is cold, we're using more idle air bypass than when are up to our operating temperature here.
06:59 So we can see our current engine RPM here so we're sitting 770, 780 RPM which is a little bit lower than I want, even though the engine is actually idling quite happily.
07:09 And at the moment because we're in open loop mode we don't actually have an idle speed target table so few ways of going about this, what I'm going to do here is just simply grab the cells to the right of where I'm operating and by using the shift and Q key, I can increase that duty cycle and we see that our idle speed's coming up, we're now sitting at 850 RPM, I'm going to get that to 900 RPM, should be a pretty happy place for this to be idling and looks like we've got that dialled in.
07:41 We'll just have a quick check of our air/fuel ratio as well.
07:44 Got a little bit richer but I'm pretty happy with that, 0.94, 0.93, at the moment I don't see the need to make a change so our idle speed control system is working and it is responding.
07:56 Let's just go a little bit further here and we'll come back to our idle speed control setup and what I'll do is we'll go back into our mode and we'll change that to closed loop and now what we're going to do is press the escape key and we now will have a idle target RPM table which is really important.
08:16 So you can see that at higher RPM it's actually set that to 750 which is again a little lower than I want so what I'm going to do is just highlight that out to 80° and I'm going to set that to 900 and you can actually see that the closed loop control is working because when I enabled that, it actually dropped the idle speed back down to 750 so we'll set that back to 900 and that'll come back up.
08:39 And then I'm going to use the interpolate function just to interpolate this down to 20°.
08:44 So if we want to use the interpolate function, there's a shortcut key but if we, just actually highlight that again, so I've got everything highlighted that we want to change and if we right click here, we come down to interpolate we can see, interpolate horizontal is the hot key or shortcut key, shift + H and that'll just give us a nice linear progression between 1200 RPM target at 20° up to 900 at 80° and above.
09:13 So obviously this doesn't complete our idle speed control tuning but we're at least, we've at least got the idle speed control system working at operating temperature and we've proven that it is actually able to control the idle speed.
09:28 What I'm going to do is go one step further and we'll go back to our idle speed control setup and I will also just add in our idle ignition control so we'll press OK, I'll turn that on.
09:39 And what that's going to do now is use our idle, sorry our ignition timing to help with our idle speed control.
09:46 So to see how that's working, if we press escape again, we now have the option for idle ignition control so we'll click on that.
09:54 And this is relatively straightforward the way the G4X deals with this.
09:59 We have our idle ignition target so essentially this is the ignition timing we're actually targetting so all things being equal, should be cycling backwards and forwards across 10°.
10:08 Then we can simply set in our maximum, 30°, probably a little bit optimistic, let's try 26 here, 30's probably a little over advanced.
10:16 Our minimum clamp here, zero, I'm OK with that.
10:20 Do need to be a little bit careful when we're using ignition timing particularly if it's over compensating for our idle air control valve being too far open, it'll overly retard the timing and if we're sitting there for extended periods of time idling at let's say zero or maybe -5°, maybe -10° if you're getting really enthusiastic with it, it's going to be creating a lot of heat in the exhaust system so we want to stay away from that.
10:41 I want to be basically getting the idle control dialled in using the solenoid primarily and just using this ignition timing as a bit of a back stop so it is important to monitor what your ignition timing is actually doing.
10:54 We've also got the ability to control the proportion or derivative gain.
10:59 Base settings here should be enough to get you going and should work quite well and if we press I here, to go to our ignition table, we can actually see, if we monitor our ignition angle we can see that the ignition timing is moving quite rapidly as a result of that idle ignition control.
11:17 So at this stage we've got our engine idling nicely, it's up to operating temperature, we've got control of our air/fuel ratio, our idle control system works, our alternator is charging, we've got good manifold pressure, we're in a pretty good place now to be confident that the engine is operating correctly and if it wasn't already, this would be the point where I'd finally be comfortable actually putting the car on the dyno, having a reasonable amount of confidence that the tuning session should progress reasonably smoothly and we're not going to get stuck with any really obvious issues that will trip us up straight away and waste a bunch of dyno time.
11:53 Let's move on with the next step of our process.

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