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Ethanol & Flex Fuel Tuning: 2. Tune for Primary Fuel

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2. Tune for Primary Fuel

05.48

00:00 - With our ECU now configured for our primary fuel, we can go ahead and complete a full tune for that fuel.
00:07 The process I'm going to follow through here, is the HPA 10 step process that we demonstrate in our Practical Standalone Tuning course.
00:17 Again if you're not familiar with that process, please check back there.
00:21 In this particular worked example, we're not going to highlight the entire tuning process, we're just simply going to perform the process, and at the end of this step we'll go over the results that we've got on pump fuel, and talk about anything specific that we've found, that we may need to keep in mind when we move on and begin our ethanol or flex fuel tune a little bit later on in the process.
00:46 Now in particular with this engine, it is running a relatively high compression ratio, so here while we're tuning on pump fuel, I've got the expectation that I am going to end up running into problems with detonation as we move into positive boost pressure.
01:01 This is always something to keep in mind.
01:04 But of course as with any tuning exercise, we're always going to be monitoring for knock using audio knock detection equipment while we are tuning on the dyno.
01:14 We're also going to be targeting a relatively low boost pressure here while we're running on pump fuel.
01:20 The aim is to produce a relatively conservative state of tune for pump fuel.
01:25 Later on when we move onto E85, this is where we're going to be able to run more boost and set up a more aggressive tune to produce considerably more power.
01:35 Let's move on now, we'll go through the tuning process, and then we'll have a look at our results.
01:40 So we've gone through now and we've completed our tune on pump fuel.
01:44 I'll just take a few moments to go through and see what the results of that tune have been.
01:50 Now we have tuned up to 16 psi and as I had expected we do end up becoming knock limited.
01:58 At 16 psi we're actually able to get pretty close to MBT timing.
02:03 But we did try increasing the boost pressure and as we went past 16 psi we rapidly found that we ran into fairly severe problems with knock, and this really limited how much boost we could run.
02:16 Now for our purposes though this is always a good thing when we're performing a flex fuel tune, because when we know that we are heavily knock limited on pump fuel this is pretty indicative that there should be quite large gains to be had when we move on to the ethanol fuel.
02:33 Let's have a look at the dyno results.
02:35 And what we can see here is our power graph.
02:38 We have made 242 kilowatts or 324 horsepower at the wheels.
02:44 In the middle of the graph here we can see our boost pressure.
02:47 We've got our reference line running through here at 16 psi and we can see we're really close to that.
02:52 Above this we have our lambda value coming from the wide band sensor on the dyno, and again I've got a reference line running through here at 0.80 lambda which is the air fuel ratio or lambda target that I've chosen here for pump fuel.
03:09 So all things considered this is a pretty good result, this is in line with what we were hoping to achieve out of the engine on pump fuel.
03:17 Let's have a look into the G4 Plus tuning software, and we'll just have a quick look at the maps that we've produced.
03:24 So first of all we have our fuel or volumetric efficiency table.
03:29 And in this case we were running up around about the 100 to 110 kPa row.
03:36 So we can see we've got efficiency values sitting in there around about 94% peak.
03:41 It's always important to have a view of our volumetric efficiency or fuel table graphically.
03:48 What we're looking for here is something, and it should be broadly smooth in its shape, which is exactly what you can see there.
03:56 What we'll do is jump across to our ignition table now.
03:59 And again looking at the values or the area we're running in in this case in absolute pressure value, we're running up around here, around about the 200 to 220 kPa column.
04:11 So we've got, particularly where the engine comes up on boost, this is where we had to be very careful with how much timing we could use.
04:20 And you can see I've got relatively conservative numbers in there, 10 to 12 degrees.
04:24 At higher RPM we've increased or advanced that timing up to 17 to 19 degrees.
04:31 And again we can have a look at that table graphically.
04:35 Again we're expecting something that should be broadly a smooth shape where we're seeing the timing retard as boost pressure increases, and we're seeing the timing increase as RPM increases.
04:48 And particularly what we can see as we've gone into the higher boost areas, in this case at 240 kPa, which is the limit of my pump gas ignition table, you can see I've tapered the ignition timing off quite sharply and this is just a safeguard in case the boost accidentally exceeds my target.
05:07 Being that we are quite knock limited on pump fuel, I've removed that timing there just as a safeguard to ensure that if there is an occasional boost bite for whatever reason, the ignition timing should be conservative and we should avoid knock.
05:21 So at this point we've also completed our cold start tuning, our idle speed tuning, so that we know that everything essentially is complete, and right now if we were only tuning on pump fuel, we'd be ready to send this car out, and our tune is completely finished.