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Practical Standalone Tuning: Step 6: Idle Tuning

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Step 6: Idle Tuning


00:00 - Now that we've proven that we've got the engine actually running, the next step before we dive too deep into our tuning is to dial in the idle speed control, make sure that we can actually make the engine idle properly.
00:11 Now we're not going to go too deep into the idle control strategy in the Adaptronic, if you want to learn more about that you can check our our webinar archive.
00:21 However we do need to understand the basics.
00:24 It's also important to know what we're trying to achieve here and what we really want to do is first of all make sure that we can make the engine idle at a sensible RPM.
00:34 And this can save you a lot of time, there's a number of tuning situations I've come across where haven't been able to get the engine to idle at an RPM that I know it should and the result of this or the cause of this I should say, has been a mechanical issue.
00:49 Quite often this will be something to do with a cam timing issue or maybe a bent valve, now obviously none of those are issues with a rotary engine but it still pays to just make sure.
00:59 One of the keys here is understanding what the likely idle RPM should be for your particular engine and that's going to depend on the engine itself as well as the mechanical configuration.
01:12 For a typical small capacity piston engine, normally going to see idle speeds in the region of maybe 750 to 1000 RPM.
01:19 For larger capacity V8s, often the idle sped is substantially lower than this.
01:23 However when we start modifying the engine, particularly if we fit a large aggressive cam with a lot of overlap, we're going to need to raise that idle speed, it would literally be impossible to make the engine idle for example at 550 RPM if we've got a large cam.
01:36 Now a lot of this really translates to the rotary world as well.
01:39 For a stock port 13b it's reasonable to expect that engine to idle somewhere in the region of maybe 1000 RPM however if we were heavily ported, then it wouldn't be uncommon to need to set the idle speed up around 1500 so the first thing is to be realistic with that.
01:55 Let's have a look at some of the settings in our Adaptronic here that are related and we're actually going to start here by moving across to our tuning air page.
02:05 And we actually need to move across for a start to our e-throttle setup.
02:10 Now as I mentioned, we're not really going to dive into the e-throttle setup here and really as far as the idle speed control goes, we don't need to know a lot about this but there is one parameter that is worth mentioning here.
02:20 And this is the e-throttle idle authority.
02:24 So here we are using the drive by wire throttle for idle control and what this does is simply set the maximum throttle opening that will be used during idle control so 6%.
02:35 Now how that works is that that comes back to our idle settings which we'll see over here.
02:41 Let's have a quick look at these.
02:43 Click on idle settings.
02:45 And we've got a range of options here for our idle control.
02:51 What we want to do is start by looking at our base duty cycle here and this is how that idle authority of 6% works out.
02:59 So we've got our table here which is a 2D table of base duty cycle values versus our engine coolant temperature.
03:05 So when we've got a value of 100% in here, this is the maximum idle authority in other words we're at 6%.
03:13 So we can see that as our engine coolant temperature steps up or increases, of course our idle duty cycle decreases.
03:21 So we are moving between zero and 6% drive by wire throttle control.
03:26 At the same time, this works in conjunction with our second table down here which is our idle speed control.
03:34 So as I've mentioned, what we want to do is start with some sensible settings for our idle targets.
03:39 So we can see here, up to 20°C I've targeted 1300 RPM.
03:43 By the time we get up to 70°C you can see that I'm targeting 1000 RPM.
03:49 With a nice linear interpolation between those zones.
03:54 Since I've just mentioned interpolation there, that's another function that you may want to use in the Adaptronic to speed up entering values into your table.
04:01 So if for example we take our value here at 20° and then we hold down the shift key and use the right arrow key to highlight out to 70°, what we can then do if we right click here and we scroll down through our options, we can see all of the options available here, what we want to do is come down to interpolate rows.
04:21 Of course the X key will also achieve that.
04:24 So we've got our idle targets set up to sensible values, we've got some base values in our duty cycle table here and we just want to head back to our idle settings for a moment and I just want to also come down to our closed loop control.
04:39 So to start with here, we have got our closed loop control disabled.
04:44 And this is important, again I'm not getting too deep into the idle control settings here, it's important when we are starting out that we actually set up our base duty table properly.
04:56 So this will be the base position that our drive by wire throttle in this case will go to before closed loop comes into play.
05:03 Now the important aspect here is the more accurately we've got our base duty cycle table set, the less work our close loop control strategy needs to do in order to get us into our target and overall the better our control's going to be.
05:17 So with that out of the way, we're going to go back to our base idle and we're going to go to our base duty cycle table here.
05:24 The other thing we're going to do here before we start the engine is just add a gauge for our battery voltage so we can make sure that our alternator is charging.
05:32 So we can do that by coming over to our gauge area, we'll right click, we'll click on add new display and text gauge, I'm going to use a text gauge in this instance, you can search through the menu structure here to find what you're looking for but I find an easier solution, if you know roughly what you're looking for is to use the filter criteria.
05:49 I'll enter volt there and the particular parameter I'm looking for is our voltage 12 volt.
05:56 So what we'll do is choose that and click OK.
05:59 Alright so we've got our little voltage display up here and we'll just position that where it suits.
06:06 So at this point, what we're going to do is start the engine again.
06:09 Now we can go through the process of fine tuning our idle base duty, essentially until we're on our target, so let's get up and running and we'll go through that process now.
06:27 Alright we've got our engine up and running and we're just at the moment using a little bit of throttle just to keep the engine idling, we can see there is a little blue line showing where abouts we are in this table so at the moment we're at about 70°.
06:44 Just coming down to our idle target there.
06:46 We can also see though, we are quite lean at this point.
06:49 So obviously I haven't got a tune up in the engine at the moment.
06:52 So this can be a case of scrolling backwards and forwards to our fuelling.
06:56 At the moment we are in this area here so again what I'll do is I'll just make a couple of broad changes, not trying to be too accurate at this point.
07:03 Obviously we haven't got our tune particularly accurately dialled in right now.
07:10 Looks like we are pretty well on our lambda target at the moment give or take so what we'll do is we can now head back to our idle base duty.
07:22 So at the moment we are sitting at about 72°, we can see that our idle speed is actually pretty close to our target, we're sitting at around about 1060 through to 1100 so our duty is probably just a touch high here.
07:35 We're sitting now between 70 and 80° so we'll just bring the base duty down here at 70° and at 80° a little bit, we can see we come down onto our target there, we're about 1000 RPM now, close enough for the purposes of our demonstration here.
07:53 And we can just manipulate those duty cycle values until we are on our target.
07:57 Now we also will be bringing in here some idle ignition control to help us but right now, for the purposes of our demonstration, we're on our target of about 1000 RPM so that's the first thing.
08:09 Now we can see that now that our engine's been up and running for a little while, our lambda's a little bit rich so we'll go ahead and dial that in.
08:16 We can see that our manifold pressure's sitting around 40, 42 kPa so nothing wrong with that, we've got good healthy manifold vacuum, we can also check our battery voltage, we can see that's sitting at about 14 volts and with our alternator charging, we should be seeing between about 13.8 and 14.2 volts so everything's looking quite healthy here.
08:35 This is a good time to go back and readdress our base ignition timing and dial that in accurately now that we've got the engine actually at RPM with it idling.
08:44 So we can go and dial that in accurately.
08:47 And we also may want to come back and readdress our differential fuel pressure, our fuel pressure setting.
08:52 You remember that we were targeting 350 kPa, we're actually a little bit under that at 335 so we could increase the pressure on the top of our fuel pressure regulator a little bit and get right onto our target.
09:05 So while I've been talking here we are still warming up a little bit so we're getting up to about 83° and what I'm going to do is just reduce the duty cycle in the 90° and above, probably also come back down and just take a little bit out of our 80°.
09:22 So again we're back down to our idle target give or take.
09:25 Let's have a quick look over at our fuelling now and we will go back to our fuel map one and we can pull a little bit of fuel out there.
09:34 You can see that we are interpolating just a little bit obviously between 1000 and 1250 RPM so what I'll do is just reduce the fuelling in both of those columns until we're on our target, we're pretty close there.
09:50 Sitting a little bit richer than our target but at this point, everything's looking pretty good, our idle speed's under control, mechanically our engine checks out, we've got control over our fuelling so at this point we're ready to move on and actually begin our steady state tuning process.

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