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Ethanol & Flex Fuel Tuning: Blend Table Operation - Practical Demonstration

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Blend Table Operation - Practical Demonstration

07.16

00:00 - In this module we're going to have a look at how the blend table functions.
00:04 We're going to demonstrate this live using our Toyota 86 fitted with our Motec M150 ECU Now the specifics of the ECU aren't too important.
00:13 What we're going to be doing is looking at a really simple example where we're holding the car on our main line dyno in steady state, and we're going to look at how the blend table affects our final ignition timing.
00:25 So what we can do is have a quick tour of the software and I'll show you what we've done to set this up.
00:31 Let's move first of all to our gasoline ignition table.
00:34 And you can see what I've done here is I've set a section of the gasoline ignition table to 20 degrees.
00:43 So particular that's between 30 and 60 kPa and between 1500 and 2500 RPM.
00:49 I've just set a big block there so that we're not going to be affected by any interpolation from surrounding cells.
00:56 So that's our gasoline ignition map.
00:58 We'll now move across to our flex fuel worksheet and we can see that we now have our ignition timing table for E85 or for our ethanol blend.
01:08 Now this time what I've done is I've set the entire block of values there to 30 degrees.
01:14 So we've got 20 degrees on our gasoline map and 30 degrees on our E85 map.
01:21 Currently we're sitting with an ethanol content of about 83% give or take.
01:26 So what I'm going to do now is get our engine up and running, we'll go into fourth gear on our main line dyno and we'll bring the engine speed up to 2000 RPM, and we'll try and hold our engine at around about 40 kPa, so essentially right in the middle of this table.
01:42 And we'll have a look at how the blend varies the final ignition timing being sent to the engine.
01:49 Alright we've got our engine up and running now, and you can see that we're operating approximately in the middle of the block of cells that we've set there.
01:57 So at the moment we've got an ethanol content of 83%.
02:01 Let's just have a quick look at our blend table and see what that's currently doing.
02:05 If we look at our blend table here for our ignition timing we can see that the blend is set to 100% any time we're at 80% ethanol or above.
02:15 Now remember a value of 100% means that the ECU will be taking its timing value, the final timing value, solely from our flex fuel ignition timing table.
02:27 So in this case remember we've got that set to 30 degrees, so we can expect our final ignition timing delivered to the engine to be 30 degrees.
02:36 We can also see we have a parameter here on the right hand side showing our current fuel ethanol ignition timing.
02:43 This shows how much ignition timing is being added by the flex fuel system over and above our gasoline ignition timing table which you'll remember was 20 degrees.
02:54 So at the moment the flex fuel system is adding 10 degrees to get to a final ignition advance of 30.
03:01 Now to make that really easy and clear, let's just have a look at our time graph here, we'll full screen this, and we have all of our parameters to do with our ignition timing being displayed here.
03:11 So first of all we have at the top our fuel ethanol ignition timing blend.
03:16 We know at the moment that's sitting at 100%.
03:18 Below that we have the final ignition advance being delivered to the engine, which is our blue parameter that's showing 30 degrees.
03:27 Below that in purple we have our fuel ethanol ignition timing table value.
03:32 This is coming from our ignition timing table from our flex fuel system.
03:37 We know that that's also 30 degree.
03:40 And finally at the bottom we can see our ignition timing main value, which is our gasoline ignition timing table value, which we know we've set to 20 degrees.
03:49 So we can see all of those parameters and how they're varying.
03:52 Let's close that down now and what we'll do is we'll make some changes to our blend table.
03:57 What I've done here is I've just highlighted the two cells that the ECU is interpolating between, 80% and 90% ethanol, let's set those to 0%.
04:09 What that's going to do is mean that the ECU is now focusing solely on the value from the gasoline or main ignition timing table.
04:18 We can see that our ignition timing parameter here to the right hand side is now showing zero degrees advance.
04:25 This means the flex fuel system is now adding no additional timing.
04:29 Let's again full screen our time graph, and we'll be able to see exactly what's going on in our time graph.
04:36 Let's look at our parameters here.
04:38 And we can see that our current fuel ethanol ignition timing blend value, so that's the number in our blend table, is zero, that's what we've just set it to.
04:48 We can see the final ignition timing being delivered to the engine, the blue parameter, has now dropped to 20 degrees.
04:55 We can still see that the values from our fuel ethanol ignition timing table, still 30 degrees, and our ignition timing main table is still 20 degrees.
05:06 And we can also see if we move this across we can see the point where we made that change to the blend table.
05:14 At this point the blend table value is 100% and we can see that the final ignition timing value being delivered to the engine is 30 degrees.
05:22 As we move across that step we can see the blend value drops to 0% and the final ignition timing value is dropped to 20 degrees, our main ignition timing table value.
05:35 Let's try a blend in between now though.
05:38 And we'll set this to 50%.
05:42 When we set that to 50% remember the ECU is now interpolating halfway between those two tables.
05:48 We have 20 degrees in our gasoline map, we've got 30 degrees in our ethanol map, so we can expect the final ignition timing being delivered to the engine should be halfway in between or 25 degrees.
06:01 Let's have a look first of all and we can see over on the right hand side the amount of additional ignition advance being delivered to the engine now is five degrees.
06:10 This is what we'd expect, half of that difference of 10 degrees.
06:14 And let's just full screen our time graph so we can see what's going on there.
06:19 We'll just move across to the point where I made that change.
06:23 We can see the blend value changing right here.
06:26 And we can see that our blend value at this point is sitting at 50%, this is after I've made that change.
06:35 The final ignition timing now being delivered to the engine is 25 degrees so halfway between those two table values.
06:44 On the left hand side before I made that change remember, our blend value is 0%.
06:49 That's focusing solely on the main ignition timing table for gasoline.
06:53 And of course the ignition advance being delivered to the engine is 20 degrees.
06:58 So that's a quick demonstration of how the blend functionality works in a flex fuel system.