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Practical Standalone Tuning: Step 2: Trigger Setup

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Step 2: Trigger Setup

14.48

00:00 - The next step of our process is to set up our trigger inputs and the trigger inputs are the most critical inputs to the ECU because all of the fuel and ignition calculations are based around this information being valid.
00:13 Those trigger inputs, what I'm referring to here is the engine speed and engine position inputs.
00:19 This tells the ECU how fast the engine is turning and where abouts in the engine cycle it is.
00:25 This information is critical as well if we want to run sequential injection and direct fire ignition because we need both of those pieces of information As I've already mentioned, we have switched from the factory Nissan 360° optical trigger system here to an NZ Wiring 24-1 trigger setup so there is a bit of work to do to set this up.
00:50 Let's get stuck in and we're going to actually start on our output setup, our output function setup on our vehicle functions 1 tab and we're going to start by disabling our fuel pump.
00:59 We can do this by simply coming down to the output channel here and you'll recall that we have already tested this previously.
01:05 For now though I'm going to set the fuel pump output channel to off.
01:09 This means that the fuel pump isn't going to run so we've got no chance of the engine trying to start as we're actually going through this process.
01:17 We really want the engine to be able to crank over without any risk of it trying to fire up because we're not at the point where we want the engine to fire just yet.
01:24 Alright with the fuel pump disabled we're going to now come across to our engine setup tab.
01:31 We've already looked at some of these options and we're going to start here with our engine decode setup which is for our trigger input and sensor main.
01:39 The first setting we've got here is for our engine decoding mode.
01:42 And you'll see that I've already selected here, multi tooth custom which is what we need for a multi tooth missing trigger system.
01:50 Over on the right hand side however, you can see we've got a fairly extensive list here of predefined trigger systems for a lot of popular engines so if you're covered here then it's simply a case of selecting the suitable option.
02:04 If we actually scroll down here and we find our Nissan options we'll see that if we look at option 75 here, this is the stock Nissan 360° optical trigger.
02:16 So if you're running the stock system that is what we want to choose.
02:19 So got the right decoding mode, the next setting we have is our engine speed calculation which defines the number of degrees of crankshaft rotation over which the EMtron will average the engine speed.
02:29 Guidelines here as per the help file, a good place to start is to take the number of degrees of crankshaft rotation for an engine cycle, obviously in this case, 720° and divide this by the number of cylinders, in our case 6, so we're using a number of 120 in there.
02:46 Our next option here, our sync lockout RPM so here, this is a little irrelevant to us because we aren't using a sync input but we can with a missing tooth trigger wheel, on the crank for example, choose to ignore the sync input once the engine is up and running because it then can track the location in the engine cycle by counting the number of teeth and looking for the missing tooth.
03:09 I would advise wherever possible to avoid that, it can cause some other trouble and realistically it is a bandaid for other problems that are potentially ocurring in your trigger system.
03:20 So again for our case, our purposes though, that is an irrelevant selection.
03:25 Alright so that's our main sensor setup done, let's go back, pressing the esc key we'll come down now to our multi tooth setup and press enter.
03:32 Now this is all pretty self explanatory stuff here, we start with the number of teeth versus the missing teeth.
03:39 So our crank index count, so this is the number of teeth on that trigger wheel including the missing tooth, this is important.
03:45 So generally when we talk about a 24 - 1 trigger wheel what we're talking about is a wheel that's been manufactured with 24 evenly spaced teeth and then one of them has simply been cut off.
03:56 Now reality it probably was never machined in the first place but that's how we can think of that style of trigger wheel.
04:02 So we want to include the number of teeth as if there were no missing teeth so 24 there.
04:07 Obviously the next one our missing count, very simple, how many missing teeth are there, in our case 1.
04:12 There's no fixed rules on what we must use for a missing tooth wheel, 24-1 is relatively common, 36-1, 60-2 so it's just a case of understanding what your trigger wheel actually has.
04:27 We also need to define where abouts the wheel, the trigger disc is located so in our case it is located on the camshaft.
04:34 We then have the option to either use or disable the sync input.
04:39 We can see over here, we've got our options of having that disabled, turned off, we can locate it on the crankshaft, the camshaft or custom.
04:46 So again in our case, we're not using the sync input, it's not required, 24-1 missing tooth wheel, located on the camshaft.
04:54 I've got some information here then on our gap detection method as well and in most instances there's not going to be any need to make changes from the default values there.
05:03 So we can skip past those.
05:06 So now the ECU knows what it's expecting to see however we still need to actually tell it what style of sensor is fitted so let's press esc again and what we can do is come down to our crank index setup and we'll start with our crank index sensor.
05:21 So here we can see that we've got a few options to select.
05:25 The first and key one is what type of sensor are we using? We're using a magnetic or varyable reluctance sensor, that's what we've selected, the other common option would be a hall/optical sensor.
05:37 That what we would be using for the factory Nissan sensor there.
05:41 We also need to define the trigger edge that the ECU will trigger off.
05:47 Now with a magnetic sensor, this is very critical because if we have this wrong, we're going to end up suffering from timing drift and that can cause big issues.
05:56 So typically with a reluctor sensor we're going to set this up, we're going to wire it so that it will trigger off the falling edge.
06:04 I still use that as a default method of wiring because a lot of ECUs won't actually give us the option to switch the trigger edge like the EMtron does so falling edge, that would be default, here we do have the ability to select rising if required.
06:21 Coming down, the greyed out option we have here for our crank sensor pullup, with a variable reluctance sensor we don't need a pullup so that's greyed out.
06:29 With a hall or optical sensor we will typically need to enable that pullup resistor, otherwise we're not going to actually see a signal and that's a really easy place to come unstuck when you're setting up a hall or optical input to the ECU.
06:43 So at this point the majority of the work's done, we do also have to consider our arming threshold, so we can find that here, crank sensor arming threshold.
06:51 This is a simple 2D table and it defines the voltage above which the signal needs to rise before the ECU will actually arm and start looking for a valid trigger input.
07:02 Basically this is here to allow the ECU to define what is noise and what's a valid signal so we want this arming threshold to be at a level that's above the background noise that's always going to be present.
07:16 And this is something we need to consider with a VR sensor because the arming threshold or the voltage amplitude from the input will actually increase with RPM.
07:27 So we can see for example down at 0 and 500 RPM we're down around 0.4-0.6 volts.
07:34 Once we're up above 7000 RPM, we can see we're sitting above 4 volts.
07:38 It's actually a nice function with the VR sensor because at higher RPM it does give us a really nice signal to noise ratio.
07:46 This default table is most likely going to be sufficient to get you up and running and then you can come back and refine the table, the arming threshold as required.
07:56 One little trick that can trip you up though, if your gap between the trigger tooth, the trigger wheel and the sensor is large, you may find that down at the cranking RPM you may find that you're not actually getting the voltage exceeding the trigger input and basically you'll crank the engine and see no RPM.
08:15 If that's the case, you'll be able to see this also on your scope to make sure that there is a signal there, we'll look at that in a second.
08:21 If that's the case it's simply a case of reducing the numbers in that cranking RPM area.
08:26 Now it's also worth talking about here what should our arming threshold be? And the rough rule of thumb here is we're going to use our scope and we're going to see what our peak voltage amplitude is on the signal and various RPM points and generally we want our arming threshold to be around about a third of the peak voltage so that should give us a good signal to noise ratio that's going to work really well.
08:50 However for the moment this is going to be suitable to get us up and running.
08:55 Alright so our job's really done here.
08:57 If we go back to esc we can see that if we are running a sync sensor we've essentially got exactly the same options available for the sync sensor so I'm not going to go through those, they're just a rinse and repeat of what we've already looked at.
09:09 We now want to actually crank the engine and make sure we are receiving a valid input so there's a few things we want to be checking here.
09:18 Over on the top right hand corner in our main dash display we can see we've got our engine RPM so we want to be looking for a good stable RPM.
09:27 At cranking speed it's going to depend on your compression ratio and your battery voltage, probably anywhere from 150 to maybe 250 RPM.
09:35 The RPM is less relevant than the fact it should be reasonably consistent.
09:39 If you're seeing big oscillations in the RPM that's indicative of a trigger problem.
09:44 We also down here at the bottom have some live values that will come up here showing us the condition of the trigger input.
09:52 Easier way to see all of this information in one place though is if we go up to our utilities tab and we click on ECU run times.
09:59 This will bring up a huge amount of information depending on what specific function or task you're completing.
10:07 And you can see here we are already on our triggers and limits run time tab.
10:11 So this will show us all of the information we are interested in.
10:15 Particularly over here at the top under engine decoding, we're going to be able to see our engine speed as well as crank and sync errors so that's where we can view our engine speed.
10:26 We'll also be able to see our engine decoding status and we should see that basically everything here goes green showing that we are triggering correctly.
10:34 So let's try cranking the engine and we'll see what we've got.
10:39 Alright so we've got a fairly consistent 150 RPM.
10:41 Everything's green there, obviously we do have no sync signal so that's to be expected so all looking good there, we know that the ECU is triggering, that RPM was consistent.
10:52 So looking like we're getting valid information into the ECU.
10:55 We will also have a quick look at the scope function as well because this is quite useful.
11:01 So that's under the utilities tab that we're already on.
11:04 On the left hand side we can see we have our scope.
11:08 The scope function really is just like any normal oscilloscope with the same functionality.
11:13 We have the ability with the built in scope to display up to 4 channels which we've got available along the bottom.
11:20 In this instance, we would normally use this to display our engine speed, our crank synchronisation inputs as well as any cam position inputs.
11:29 But of course we are only using our crank input so you can see I have disabled everything else, we've only got channel 1 being visible here.
11:38 We've assigned this to the crank.
11:40 We can also select the volts per division, so this is for our vertical divisions there and this allows us again to see what the peak amplitude is which is important when we are selecting the arming threshold.
11:53 So the process here what we're going to do is we're going to start cranking the engine and then we're going to click on the little start button in the top right.
12:01 That'll start gathering data.
12:03 Once we have gathered enough data, generally a couple of seconds of cranking is more than sufficient.
12:07 We can press that button again and we'll actually say stop once it's started recording and then it'll download and display that data so let's go ahead and do that now.
12:21 Alright so we're just getting the data ready to display here and we'll be able to see that trace, and we've got it displayed there on the left hand side.
12:29 So for a start what we want to do is actually zoom in a little bit so we can start to see that signal.
12:34 And we'll just scroll along here until we've got our missing tooth visible.
12:40 So we can get a lot of information from this.
12:42 Particularly if you've got an unknown trigger, maybe one that's a little bit harder to get access to, you don't actually know how many teeth it is, you can literally count the teeth off this.
12:52 We can see the missing tooth here because it is represented by a gap.
12:56 First thing we want to do here is just check that we are seeing a valid signal, obviously we are.
13:01 We also want to now check that polarity which we've already discussed so for a variable reluctance or magnetic sensor, what we're expecting to see is exactly what we've got here, the voltage starts low, comes up through zero, climbs again and then it's going to essentially drop vertically back down through that 0 plane and that's the point where it crosses the 0 volt plane where the ECU will trigger.
13:24 So if we had our polarity around the wrong way, this would literally be an inverted form of what we've got now.
13:30 Of course if that was the case, you've got two options, you can reverse the polarity, given that a magnetic sensor is just two wires, that will give us the flipped signal like we're seeing now, or alternatively because the EMtron does allow the trigger off the rising edge you could select that.
13:44 Anyway we're good to go here so no problems.
13:46 The other thing we can look at here is our peak voltage which at the moment you can see, cranking speed it is varying a little bit but we're seeing the peak voltage around about 1.2 to 1.3 volts so it's actually quite a strong voltage.
14:01 You can actually also note there there is a slight offset from zero volts so that's how we can use the scope functionality.
14:08 Everything's looking good there, if we did have a synchronisation input we can also make sure that the location of the synchronisation input isn't occurring in an area where it's likely to cause trouble, coinciding with the missing tooth or something of that nature.
14:23 Or coinciding with one of the other teeth on the crank.
14:26 In this case, obviously not an issue for us so we can close that down.
14:30 At this point we're ready to move on however it's worth also mentioning just so we don't end up getting tripped up by this in a later step, remember we have disabled that fuel pump, this is the perfect time to reenable that fuel pump.