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Practical Standalone Tuning: Step 4: Base Ignition Timing/Fuel Pressure

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Step 4: Base Ignition Timing/Fuel Pressure

05.50

00:01 - So our next step is to set the base ignition timing and the base fuel pressure.
00:05 We're just gonna deal with the fuel pressure first because on this particular car that's really easy, we can't do anything.
00:11 The car's got a factory fuel system in it.
00:14 As with most late model cars, it's a returnless fuel system.
00:18 So the fuel pressure regulator is fitted in the tank and it's not vacuum referenced.
00:23 So basically it runs a fixed 400 kPA, four bar, or 58 psi.
00:29 However I just want to show you how that would look in the software and what effect that has.
00:35 So you already saw that we've set up a fuel pressure sensor input in the initial setup phase.
00:43 Now if we go through to the injector tables, you can see here in the injector linearisation table for the port injectors we have this differential fuel pressure reference.
00:56 So basically the ECU is going to use the input from the fuel pressure sensor as well as the input from the manifold pressure sensor to work out a differential fuel pressure.
01:08 So what that means is the difference between the fuel pressure and the manifold pressure.
01:12 So once it knows that, that basically tells the ECU where abouts in these particular tables to reference and that's going to help keep our injector linearisation much more accurate.
01:24 We're gonna get much more accurate control of our fuelling.
01:28 So in a conventional ECU without linearisation data, it would use that for the injector dead time table potentially.
01:37 OK so now we'll move onto the base ignition timing calibration.
01:42 Again because this ECU comes with a base map, it's preconfigured and it's ready to go, technically we don't need to do anything.
01:50 As a professional tuner, regardless of how it comes to me, I will always check and make sure that the base ignition timing is correct.
01:59 I don't like to trust other tuners, I don't like to trust ECU manufacturers, I need to know for myself that the ignition time is 100% accurate because if you can't trust that and you're relying on it, it's very easy to end up with engine damage if that base ignition timing is a few degrees out.
02:18 So by setting the base ignition timing, what we mean is calibrating the ECU so that the ignition timing that the laptop is displaying is exactly the same as the ignition timing the engine is receiving.
02:31 Now the first step with that is to actually get a timing light and physically fit it to the engine.
02:37 With this particular engine it runs coil on plug.
02:40 That can be a little fiddly but fortunately with the FA20, the wiring to the coils have enough ignition energy that we can actually pick up off that.
02:51 So once we've got the ignition timing light connected to a coil lead, it's gotta be the number one coil lead, we can physically see the timing that the engine is receiving.
03:03 Now if we go to our rev sync page here, and you can see down the bottom we've got a reference offset and in brackets it's CRIP test.
03:14 Now CRIP is, for anyone who's familiar with Motec, that's always been their term for base ignition timing.
03:21 It stands for crank index position.
03:23 So it's indexing the position of the timing relative to the signal the ECU is getting from the pickups.
03:31 So what we can do is we can set the ignition timing mode from normal to check timing.
03:38 Now what that does, as soon as we do that, it fixes the ignition timing at the timing value we've got here in our ignition timing check.
03:47 In this particular example here we've got that set at 10 degrees.
03:50 What that means is regardless of engine RPM, regardless of load, the ECU will supply a fixed 10 degree ignition advance.
03:57 OK so that makes it really easy for us to see on the timing light and compare.
04:01 Are we actually seeing 10 degrees at the crankshaft? If we aren't, then what we can do is go up here to our engine speed reference offset, and we can adjust this offset up or down, until we correct that difference and our ignition timing is 100% accurate.
04:22 Now once we've done that, if you've got the car idling, particularly if it's idling quite low, you may notice that the ignition timing is jumping around a little, it's not uncommon, particularly on older trigger systems, to see that ignition timing moving around three or four degrees, maybe even five degrees.
04:42 It doesn't really help us set the ignition timing.
04:44 If that's the case bringing the engine RPM up with the throttle and holding it around 1500 to 2000 RPM, you'll often find that that makes the timing become a lot more stable.
04:57 Basically the ECU is seeing a more consistent trigger pattern and it can work out more accurately what the ignition timing, when the ignition event should be.
05:05 So bring it up to a point where the ignition timing is steady, and that's where you want to be setting your base ignition timing.
05:12 Once you've set it and you know it's accurate, I also like to increase the RPM, so maybe up to about 3000, 4000 RPM, just rev it up, watch what the timing does, and make sure that it stays stable.
05:25 It's not uncommon to see the timing move or drift by maybe one or two degrees.
05:30 That's noting to worry about.
05:32 If you're seeing much more than three or four degrees drift though, that indicates a problem that you really want to address and fix.