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Practical Standalone Tuning: Step 2: Trigger Setup

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Step 2: Trigger Setup

08.49

00:00 - The next step of our process is to set up the trigger inputs to the MegaSquirt ECU so that it has accurate information about engine speed and engine position.
00:08 Without this information, none of the fuel or ignition calculations can be completed accurately so these are arguably the most important inputs to the ECU.
00:18 Now all of this information in the Mazda B6 engine is derived from an optical cam angle sensor mounted off the back of the inlet cam on the engine.
00:28 Now let's have a look at the settings that we need to adjust here and we'll go to our ignition settings, click on our ignition settings drop down menu and we're going to go to our ignition options/wheel decoder.
00:42 This will open up our window here where we've got the necessary adjustments.
00:46 Now in this instance the main setting that we're going to be concentrating on here is our spark mode.
00:53 So you can see that this is actually set to 4G63 which on face value does seem a little bit unusual however it just so happens that the trigger pattern for the Mazda B6 engine and also the 4G63 Mitsubishi engine share the same trigger inputs.
01:10 You can of course open up this drop down menu and select any of a range of different trigger inputs if it doesn't happen that you are tuning a Mazda MX5 or a Mitsubishi 4G63.
01:22 One thing that I will just mention here is that you can see we do have another option for a Miata '99 to '05 model year.
01:31 So be careful here because this might seem like a sensible selection but in our particular case the correct option we want is for our 4G63 trigger pattern.
01:40 Next we have our trigger angle or offset.
01:44 So this is essential in accurately zeroing or degreeing in our timing.
01:50 So this is the function we're going to go through here when we get to the step where we're setting our base ignition timing.
01:56 And this just helps us basically calibrate the ignition timing so that the timing that we're seeing on our laptop screen is exactly the same as what the engine is receiving if we look at the timing using a timing light.
02:07 So again we'll get to that a little bit later on.
02:10 Next we can come to a range of settings that are going to be critical for the rest of the trigger system.
02:17 We start with our first option here which is called skip pulse, as you can see there this is set to three in the default base map here.
02:25 Essentially what this defines is how many input pulses the ECU will ignore when the engine first starts cranking before it'll start its fuel and ignition calculations and begin synchronising so this just means that any inputs when the engine first starts to crank which may result in trigger errors, will be ignored.
02:44 Moving down, we have our ignition input capture.
02:48 So this defines whether the ECU will trigger off the rising or falling edge of your trigger input.
02:55 Now this has to be set to suit your specific trigger input, there is information in the MS3 Pro manual about various trigger inputs and which way around this should be set.
03:06 Alternatively you can use the composite logger to actually view your trigger input in essentially like an oscilloscope and decide which edge you should be triggering off.
03:15 Now if you do have this wrong, you're likely to end up with trigger errors, the ECU not being able to synchronise at all or ultimately, particularly with a VR input, a variable reluctor input, you're going to end up with timing drift as your RPM changes.
03:29 So again rising edge is correct for our application here.
03:33 Likewise our spark output which we've already talked briefly about.
03:36 This needs to be set up based on your ignition system and for our waste spark Mazda ignition system this will be set to going high.
03:44 We can next set up the number of coils that are fitted to the engine.
03:49 In this case we are running the factory waste spark ignition system so we've selected as such, you can also run single coil, coil on plug, or you can run the coil on plug in a wasted application.
04:02 Next we've got our spark hardware in use function.
04:06 So in most instances this should be set to spark.
04:10 However if you are running a CDI ignition box or something of that nature, you can set this to tacho out instead.
04:17 Our next input here is our cam input, so this defines what the cam input will be.
04:24 You can see that this is listed as CMP or camshaft position sensor, which is what we want here.
04:31 This is what we're going to be using in most instances.
04:34 So at this point we've got our main trigger inputs set up, the ECU should give the information on engine speed and position.
04:40 There is a little bit more to discuss on this particular window though as well.
04:43 On the right hand side for a start we've got our fixed advance option.
04:48 So in this case you can see that we are using a table, we can set a fixed advance timing.
04:55 Of course in most instances we're going to want to use a three dimensional table there.
04:58 We've also got this option here labelled use predictive and you can see that this is set to first derivative prediction, or we can turn this off.
05:08 Now essentially what this does is it allows the ECU to adapt the ignition timing when the engine speed is increasing or decreasing rapidly.
05:15 Next we've got some settings for when the engine is defined to be cranking.
05:20 We've got our ignition dwell, we can see that's set at six milliseconds, and we've also got the ignition advance that will be used during cranking.
05:28 Generally somewhere in the region of about 10 degrees is a pretty good starting point for our cranking ignition timing.
05:35 The dwell will depend on your particular coil.
05:38 What you're really wanting to do here is look at the voltage during cranking and make sure that you have sufficient dwell to get sufficient spark energy.
05:47 Moving down the next option we've got here is Toyota Multiplex, we can enable or disable this, this is only going to be useful if you are using a Toyota ignition system, in our case clearly we're leaving that off.
05:59 Next we have our dwell type and in most instances here we're going to leave this set to standard dwell.
06:05 However in some instances, particularly if we are using a capacitive discharge ignition system, we may choose to use fixed duty instead.
06:15 Next we've got the ability to select whether or not we want to use a dwell table.
06:20 In this case the dwell table is set to off or we can enable it if we prefer.
06:24 When we have the dwell table disabled, instead we'll have a nominal dwell time.
06:29 Normally in the range of three to four milliseconds, again dependant on your specific ignition system.
06:35 So this is the nominal dwell before battery compensation is applied.
06:38 We also have our spark duration, typically that's going to be in the range of one millisecond.
06:45 Moving down we've also got the ability to set the spark hardware latency.
06:50 So at the moment that's set to 50 microseconds.
06:53 This really takes into account the latency or delay in the spark actually occurring.
06:58 In particular you can find that if this is incorrectly set, you're going to get a slight difference in your ignition timing at idle compared to what you'll get at 6000 to 7000 RPM.
07:10 So you can adjust that in order to eliminate that delay.
07:13 So at this point we've got all of our base trigger inputs set up correctly and what we can do at this stage is actually crank the engine and make sure that we're getting RPM and that the ECU is synchronising.
07:24 So let's close down our window here.
07:26 What we're going to do is just crank the engine, we've currently got the ignition coils unplugged as well as our injectors so this is going to mean the engine's got no chance of starting and we're not going to end up filling the cylinders with fuel.
07:38 So what we're going to be looking at here on our gauges page is we're going to look at our engine RPM.
07:43 We're expecting to see our cranking RPM probably in the order to 200 to 300 RPM, more importantly we want to make sure that that is stable and not jumping around.
07:51 At the same time we can also see our lost sync counter, this will give us some indication on whether the ECU is receiving valid information.
07:59 We may see this count up initially when we first start cranking but once the engine RPM is stable, we shouldn't see any increments to this number.
08:09 Likewise at the moment we can see that we've got a status flag saying that the RPM is not currently synced, that should go away.
08:16 So let's just crank our engine briefly and we'll see if everything works as expected.
08:27 So we can see everything looks good there, we've got a stable RPM, we're seeing around about 260 RPM, the ECU was synchronising correctly, we saw no increments to our lost sync counter.