Practical Standalone Tuning: Step 2: Trigger Setup

Back to course

Watch This Course

$229 USD $114.50 USD

-OR-

Or 8 easy payments of only $14.31 USD Instant access. Easy checkout. No fees. Learn more

Enroll Now
8 easy payments of only $14.31 USD

Course Access for Life

60 day money back guarantee

Step 2: Trigger Setup

07.37

00:00	The next step of our 10 step process is to configure our trigger inputs.
00:04	And these are the most important inputs to the ECU, giving it information around engine speed and engine position.
00:11	All of the subsequent calculations around fuel delivery and ignition timing are based on these inputs, so basically if we've got these wrong, then all bets are off.
00:20	We're probably never going to get the engine to start, or if it does, it's going to run very poorly and we're going to end up with a huge number of problems that we're going to have to fault find.
00:31	As I touched on briefly in the last step, this is actually greatly simplified in our particular example here with the Holley Terminator given that it is a predefined configuration for the LS24X trigger input.
00:46	But let's go over this anyway.
00:48	So, we'll come into our systems parameters and we come into our ignition parameters and this is where we sort of touched on this lightly already.
00:58	So, we've got our ignition typeset as GM LSX 24 tooth.
01:03	Huge range of options here, but when we've got this configured we can see that we really don't have any adjustability, there is no ability to offset our ignition timing, there's no inductive delay and there is no dwell table.
01:19	So, it really does make it much easier if we've got something like this that is predefined because there's just no room for error, everything is predefined by Holley, there's nothing left for us to do.
01:30	I do still like the ability to be able to adjust our base ignition timing or our offset for our ignition timing slightly though.
01:38	Even with a configuration like this, manufacturing tolerances can mean that our ignition timing might move around very slightly from one engine to another and here we've got no ability to adjust this.
01:51	Let's just have a look through this in a bit more detail though for something that is a little bit more custom and there is some nice functionality actually that Holley have added in here.
01:59	So, we'll go into our drop down menu and what I'm going to do is come down to custom.
02:03	Now, to be clear, as long as you are dealing with an engine that has one of these predefined trigger inputs, then that is absolutely the correct choice for us.
02:13	Now, that we've chosen custom we can see we've got this little configure button available and if we click on that, now we can define our crank sensor and our cam sensor independently along with our inductive delay and our timing offset.
02:26	So, let's just have a look at our options here.
02:29	Let's say we come down to something that's relatively common, a 36-2 on the crank.
02:34	Now, if we click on that, this is something I actually really like about Holley is that they've given us a nice graphic representation of exactly what this is all going to look like.
02:43	So, for example here we can define the tooth that will be related to TDC.
02:50	Let's say that this is going to now be tooth 18 and when I press enter, we can see as everything changes, our actual trigger wheel moves and we can see exactly where everything's going to be.
03:02	So, I actually think this is a really really nice option that Holley have brought in here.
03:06	Likewise we can just create the timing offset to set our timing as required.
03:12	Also got the sensor type, we can have digital rising, digital falling or a magnetic VR sensor.
03:18	And likewise for our cam, we can also basically have the same options available.
03:22	And let's go with this being a magnetic.
03:26	Now, one thing that I have noticed here though is that when you choose a magnetic or VR reluctor sensor, we don't have a full arming threshold table, instead it's just a single value here.
03:42	And to me this doesn't make a lot of sense because the amplitude of a magnetic sensor input is going to vary hugely based on the engine RPM.
03:51	So, most ECUs would normally incorporate a two dimensional table here.
03:55	I'm unsure of what Holley are doing in the background here, but we need to set this to a minimum voltage that's going to allow the trigger input to be picked up at cranking speed where the magnitude or amplitude I should say of the input is going to be low.
04:08	But we also need to set this high enough that it's going to ignore background noise that's always going to be present.
04:15	So, this will depend on your setup, I'd probably suggest starting somewhere around about 0.3 volts and see how you get on there.
04:21	We basically want it set as high as we can while still getting reliable triggering.
04:26	We've also got the ability to set our filtering level here as well and as usual we want to use as little filtering as we can get away with and still have a clean signal.
04:35	So, I'd start very low and only add filtering if required.
04:40	Then we come to our output setup here, so our actual ignition system.
04:44	And in this case we've got the option to go for a variety of different styles, coil on plug for example there.
04:53	And then we've got the option of how we're going to deal with our dwell.
04:56	I've already touched on this briefly, but we can see that we've got our dwell time set at 1.5 milliseconds which definitely wouldn't be sufficient, but we need to set this based on the individual coil.
05:09	If we've got the dwell time set too low then we will find that we may not have enough spark energy or we may end up with ignition misfires under higher load.
05:18	If it's too high then we can end up overheating the coil and damaging it.
05:23	Alternatively we can of course enable our dwell table and then we can set our axis here.
05:28	In this case by default it's gone to TPS via MAP, but we can look at our options here.
05:33	And generally we would have battery voltage on one of these axes.
05:39	So, we can actually vary the dwell, we'd increase the dwell at low battery voltage and we would reduce that as the battery voltage increases because we don't need to dwell the coil as long in order to fully charge it.
05:50	So, there you go, that's a bit of an introduction to the trigger system.
05:54	And if you are using something custom, this is what you're going to be dealing with.
05:58	Obviously, this does need to be set up to suit your specific engine application and trigger system, but for now I'll just revert to our default values, our default setup, so we can see the next part of this step.
06:13	Alright, so at this point we now want to actually see if we are getting a sensible RPM input to the ECU.
06:22	Basically, is everything working, are we getting input and does the ECU know what the engine speed is? So, to do this we've disconnected our coils and our injectors, so we're not actually going to be injecting fuel or actually creating spark, we don't want the engine to start at this point.
06:36	There's a couple of ways we can do this, we can see down in our little sensor panel here we've got our RPM which is currently saying stall.
06:43	That's probably sufficient in what I normally use.
06:46	We do also have a gauge panel here which I find that I just don't really use, but can be useful for our purposes here because we can see we've got our RPM gauge being displayed.
06:57	So, what we want to do here is just crank the engine, watch the RPM, make sure that we are reading sensible RPM, something that makes sense for cranking, probably somewhere between maybe 150 and 250 RPM.
07:10	We also want to make sure that the RPM is consistent and isn't jumping around.
07:14	So, let's go ahead and crank the engine briefly now and see what we've got.
07:18	OK, so our RPM's consistent at 150, 160.
07:22	Alright, so this stage we've got a stable RPM signal, we know our trigger inputs are correctly configured and the Holley ECU is able to decipher these properly, so we can move on to the next step of our process.