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Ethanol & Flex Fuel Tuning: 1. Configure for Primary Fuel

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1. Configure for Primary Fuel


00:00 - The first step of our flex fuel tuning process is to configure our Link G4 Plus ECU to suit the primary fuel that we're going to be tuning on.
00:09 Now we can select either pump fuel or E85 as our primary fuel and in this case the car's being delivered to us with a full tank of 98 octane pump fuel.
00:19 So that's what we're going to be selecting as our primary fuel.
00:24 For this step of our worked example, I'm not going to be focusing on every parameter or change that you may need to go through in order to configure your ECU prior to tuning.
00:35 We're going to assume that you already have that level of knowledge and we're going to be focusing solely on the aspects related to the flex fuel configuration.
00:44 If you do need more understanding around configuring and tuning your ECU, please check our Practical Standalone Tuning course.
00:53 Let's jump into the laptop tuning software, and we're going to start on our fuel main menu.
00:58 One of the key aspects here that we need to configure is our fuel equation mode.
01:04 You can see at the moment I've got that set to modelled.
01:07 If we double click on this we can see the options available.
01:10 And at the bottom you can see there's the modelled multi fuel equation which is what Link use for flex fuel tuning.
01:19 Now it may seem that we want to select that, however right now what we're going to be doing is really treating the ECU no different to what we would be doing if we were tuning just for one single fuel.
01:31 So we need to start by selecting modelled.
01:34 Moving down, other aspects that are important here are our engine capacity.
01:40 This is really important to have right so that the volumetric efficiency or VE based fuel model can work correctly.
01:48 This is important even when the ECU is only being tuned on a single fuel.
01:53 But it becomes even more important with a multi fuel system because this affects the accuracy as the ethanol content moves around.
02:02 So we really need to make sure that this is correct.
02:05 In this case the engine started life as a 1.8 litre, however it has been bored and stroked out to 1994cc.
02:15 Moving down we've also got some aspects to do with our fuel system.
02:19 Again this becomes even more critical for the accuracy of our model fuel equation.
02:23 Here you can see we have our fuel system type set to manifold pressure referenced.
02:28 This means that the fuel pressure will rise and fall with manifold pressure or in other words, our differential pressure should remain relatively fixed.
02:38 The differential pressure itself, or the base fuel pressure is another important aspect here.
02:44 We need to make sure that this is configured to the same base fuel pressure that our regulator is mechanically set to, in this case three bar or 300 kPa.
02:55 Now moving down we've got some parameters that are relevant to our primary fuel here.
03:01 In particular we've got our fuel density at 20 degrees centigrade, our fuel density temperature coefficient, as well as our stoichiometric air fuel ratio.
03:12 Now you may not know necessarily what these particular parameters are for your fuel, and Link make this nice and easy.
03:19 If we press F1 on any of these parameters, the help file will open up and that's going to show you the information that you need to enter for the common fuels we're going to be using.
03:31 In this case remember we are tuning on pump fuel so we can see that the suggested value there is 0.745 grams per cc and I've simply copied that value down and entered it in the parameter here.
03:45 Likewise we can do exactly the same for our fuel density temperature coefficient, F1 gives us the correct values for our common fuels.
03:54 Moving down we've also got our stoichiometric air fuel ratio and again if you're not sure, F1 will bring up the values for the common fuels we're going to be using.
04:03 With pump fuel here we've set this to 14.7:1 Now an important aspect to make sure that we do tune here is our fuel charge cooling coefficient.
04:13 Now this will be specifically set for each fuel for our primary and our secondary fuel.
04:19 And this relates to the amount of cooling effect that the fuel has on our charge, our inlet charge, as it moves into the cylinder.
04:29 So in this case we're going to be tuning that value for our pump fuel.
04:35 So this configures our fuel main table.
04:37 What we'll do now is we'll have a quick look at our injector set up as well because again, all of the aspects of our volumetric efficiency based fuel model need to be correct for the flex fuel or modelled multi fuel system to work as well as it can.
04:55 We'll go through the menus, we'll go through our fuel setup, and then into our injector set up.
05:00 And here the parameters that are really key are our injector flow and our injector rated pressure.
05:08 Now these will come from the injector manufacturer or injector supplier, in this case we're using a set of expert 1600cc injectors.
05:17 From the data sheet we know that these flow 1584cc per minute at 3 bar, remember this also relates to our base fuel pressure selection that we just looked at.
05:27 Moving down we've also got parameters here, or tables here, for both injector dead time and injector short pulse width adder.
05:35 Again these can come from the injector manufacturer and it is really important to get this data as accurate as we can.
05:44 So this really covers the two key aspects that we need to look at.
05:47 One other configuration we will look at is our ethanol content sensor.
05:51 And if we look at our digital inputs we can see that that is configured on DI 7.
05:57 Let's click on that and we can have a look at the parameters that are relevant.
06:01 In particular setting up the ethanol content sensor is as simple as double clicking on the function and selecting ethanol sensor from the drop down menu.
06:11 Once that's set up everything will just work, although it is important to make sure that the pull up resistor is set up and configured.
06:19 Once we've got our ethanol content sensor wired up, connected, and reading into the ECU, we can actually make sure that we're seeing sensible values.
06:29 You can see I've actually got our ethanol content, or ethanol percentage displayed right here on the main tuning screen.
06:36 However if we press the R or F12 key to get to our run time values screen, we can see on the general tab that our DI statuses are shown and in particular what we should be looking for here is that our ethanol sensor status is showing green, and saying that it's OK.
06:54 If we move across to our miscellaneous tab we can also actually see the two inputs coming from that flex fuel sensor.
07:02 We can see our ethanol percentage, again showing zero, as well as our ethanol temperature directly below that showing that currently it's 12 degrees centigrade.
07:11 So at this point we know that our ethanol content sensor is reading correctly, remember we are on pump fuel, so we're expecting to see that ethanol content sitting at zero.
07:21 However in some areas you may find that even pump fuel may contain some quantity of ethanol.
07:29 So it's not uncommon to see this reading, even on pump fuel, register a few percent.
07:36 So at this point our ECU configuration for our primary fuel is complete.