Practical Reflash Tuning: Step 4: MAF/Injector Scaling
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Step 4: MAF/Injector Scaling
40.23
| 00:00 | - This step is traditionally where we would be rescaling our mass airflow sensor or perhaps setting our tune up to suit a different set of injectors. |
| 00:09 | Now, in our case we're still running the factory injectors, and with the speed density operating system we're not using the mass air flow sensor. |
| 00:17 | However, part of the speed density operating system relies on the volumetric efficiency or VE table being accurately configured and calibrated. |
| 00:28 | The process we use to do this is very similar to how we tuned the mass airflow sensor, so in this case we're going to cover this step now. |
| 00:40 | Now we left off with our base ROM file. |
| 00:42 | You'll remember that our new VE tables are set up as we can see here, currently, with zeroes throughout the table. |
| 00:51 | And if we flash this into the PCM right now, our engine's not going to start and run. |
| 00:57 | We need to get some valid numbers into our VE tables before we can actually start tuning and optimising the volumetric efficiency data. |
| 01:06 | So where can we get this data from? Well, if our engine's still relatively standard, what we can do is simply take the data from our virtual VE editor and use that in our new VE tables. |
| 01:20 | But there is a catch, so let's talk about that. |
| 01:23 | We can see here the way our axis is set up on our new VE tables and our speed density tune, we have manifold absolute pressure on our X-axis and we have engine RPM on our Y-axis. |
| 01:36 | Now let's close this particular file down now. |
| 01:39 | And what we'll do is we'll reopen our original file with our factory stock operating system using the blended VE and MAF system, or virtual VE and MAF system. |
| 01:52 | And if we open up our virtual volumetric efficiency editor, you can see the problem we have is that the stock virtual VE table uses engine RPM on the X-axis and manifold absolute pressure on the Y-axis, so, our issue here is that our axes are transposed and we can't simply copy this data across and dump it into our new VE tables. |
| 02:17 | So the solution here is to do some basic editing using Excel. |
| 02:22 | It's nothing particularly taxing and I'll talk you through it now. |
| 02:25 | What we're going to do is click in the top left corner to highlight the entire table. |
| 02:30 | Then I'm going to right click and I'm going to use the copy with axis function. |
| 02:34 | And this copies the table data as well as the axis data. |
| 02:38 | So we're now going to open up Excel and by using the control and v paste function, we're going to paste that data, as well as the axes data into Excel. |
| 02:49 | So now we've got this data, we need to simply highlight the entire table of data again. |
| 02:57 | And we're going to right click, and we're going to copy this data. |
| 03:04 | We're going to re-paste the data a little bit further down in our spreadsheet. |
| 03:08 | However, this time I'm going to right click and I'm going to use the paste-special function. |
| 03:13 | And when we open up the paste special function box, you can see we have the option labelled here transpose. |
| 03:21 | And what this is going to do is swap out X and Y axes. |
| 03:24 | So we're gonna click on that, and we're going to press OK. |
| 03:27 | And you can see, in our original data we have manifold absolute pressure on our Y-axis, and if we move down and look at our new table, you can see now, conveniently, it's been modified and we now have engine RPM on our Y-axis. |
| 03:43 | This is done exactly what we need. |
| 03:46 | Now what we can do is simply copy this data and copy it and paste it into our new VE tables. |
| 03:54 | So let's do that now. |
| 03:56 | We'll highlight the data. |
| 03:57 | This time we only need to highlight the data, not the axis values as well. |
| 04:01 | We'll go back to our editor. |
| 04:04 | This time we need to close down our original file and we're going to open up our new One Bar SD file, Speed Density file. |
| 04:11 | Now remember, we have our three VE tables. |
| 04:14 | We need to make sure that they're all the same. |
| 04:16 | So we're going to highlight our entire table and control-V, we'll paste our data into the VE table. |
| 04:25 | So let's do that all three of our VE tables, so we make sure that they are all the same. |
| 04:31 | And also, if we look at the table, graphically you can see now we have a conventional, a relatively conventional shape to our VE table. |
| 04:40 | So everything looks like we'd expect it to. |
| 04:44 | So at this point now, we can re-save our file and we're finally at a point where we can now flash our new speed density operating system ROM into our PCM. |
| 04:57 | Now, particularly if the only change we've made here is to remove the mass airflow sensor from the system, and hence our virtual VE data is accurate, in this case, we should be able to expect our engine to start up, operate, and run very much like it did with the mass airflow sensor still connected. |
| 05:17 | So let's go through the process of flashing our ROM now. |
| 05:21 | And what we need to do is click on our right vehicle icon. |
| 05:25 | Now this time we need to, instead of, as we normally do, selecting right calibration, the very first time we flash the PCM with our new operating system, we need to actually choose the right entire option, which you can see I've selected here. |
| 05:43 | Now we only need to do this the very first time we flash the ECU with our new speed density operating system. |
| 05:51 | After that we can continue by using the right calibration function. |
| 05:55 | Now I am not going to write to my transmission control module in this case, and we can click on write and go through the process of flashing this information into the PCM. |
| 06:06 | Now when we do a write entire, this will take around about six minutes, so it is a little bit longer than a standard re-flash. |
| 06:13 | Alright, let's go through the process now and we can get our engine up and running. |
| 06:17 | Now we've got our engine up and running with our new speed density tune flashed into it. |
| 06:24 | First thing we can do is have a look on our scanner, and we want to make sure that our long-term and short-term fuel trims are, in fact, sitting at zero. |
| 06:35 | This is important because remember we've put the PCM into open-loop mode while we're going to go through the process of optimising our VE table, so we need to make sure that that is, in fact, the case. |
| 06:48 | You can also see here we have our equivalence ratio of lambda commanded, versus our measured lambda coming from our wide-band lambda sensor. |
| 06:57 | Now this what we're going to be using to fill in our histogram, and let's have a look at that now. |
| 07:03 | We'll pull our histogram over. |
| 07:06 | And I've set up a histogram here, which I've called equivalence ratio error speed density. |
| 07:13 | And this is simply a histogram set up with the same axis break points as our VE table, and essentially what we're doing is logging values into this table that coincide with the error between our commanded air fuel ratio and our measured air fuel ratio. |
| 07:30 | And what we really want to do now is simply drive through as many sites in this table as we can, and fill it out with as much information as we can get. |
| 07:40 | And what we're going to end up with is a histogram that shows us how much error we have in our volumetric efficiency. |
| 07:48 | Essentially, if our measured air fuel ratio doesn't match our commanded air fuel ratio, it means that the speed density system is telling the PCM we either have more or less air entering the engine than we really do. |
| 08:03 | So any error here we want to apply to our VE table to correct it, and we're going to try to get our error as close as we can to zero. |
| 08:12 | So let's get the engine into gear. |
| 08:14 | Let's get the car into gear now, and we're going to drive through this table and start gathering some data. |
| 08:21 | Now, when we're doing this sort of testing we're gathering data in our histogram here, we want to make sure that we drive the engine as smoothly as we possibly can. |
| 08:33 | We want to make sure that we're very smooth on the throttle and we're not requesting any transient or acceleration enrichment. |
| 08:43 | So any time we've got gear changes occurring or we're making aggressive changes on the throttle it's going to affect the smoothness and the accuracy of our data, so we always want to be very, very smooth. |
| 08:54 | Other thing to consider as well is we want to make sure that our engine is at a normal operating temperature when we're gathering this data. |
| 09:01 | So we want to make sure that we're not trying to perform this testing when the engine is cold or alternatively when it's heat soaked. |
| 09:10 | So, now I've got the engine operating in fourth gear. |
| 09:13 | What I'm going to do is I'm just going to use the dyno here to control my engine RPM and I'm just going to drive the engine through as many of these sites as I can. |
| 09:25 | For the purposes of this demonstration, we're just going to go up to about 2800 RPM and gather some data there. |
| 09:33 | Normally, of course, we're going to be doing this particular test over as much of the engine's operating range as possible, but the process is exactly the same so I'm just going to gather some data up to 2800 RPM just to demonstrate the process. |
| 09:49 | Let's do that now. |
| 10:25 | Now that we've gathered some data and steady state I'm also going to keep my scanner running and we're going to have a look at gathering some data under wide-open throttle in power enrichment mode. |
| 10:37 | Now, personally, when I'm doing this testing I like to leave our power enrichment mode active so that we're still going to be targeting a safe, rich, air fuel ratio while we're under wide-open throttle. |
| 10:50 | However, we do need to be a little bit careful because as we move into power enrichment, we're going to see a momentary error between our commanded and our measured air fuel ratio or lambda value. |
| 11:04 | And this is going to end up affecting the accuracy of our histogram if we simply go through each of these RPM rows and go all the way through to wide-open throttle. |
| 11:15 | So the data that I've gathered there has all been with a commanded lambda value of 1.0, and you can see I've only gone out to about 88 kpa. |
| 11:26 | So I haven't gone into the power enrichment area of the table. |
| 11:30 | So we're now going to have a look at a wide open throttle ramp run and this is going to help us fill in the higher load areas of our histogram, and this is going to help us get our air fuel ratio dialled in under wide open throttle when we are operating at power enrichment. |
| 11:46 | So what I'm going to do now is smoothly increase my throttle opening up to wide open throttle. |
| 11:53 | And if we watch the histogram while I'm doing this what we're going to see is that as we transition around about here to our power enrichment operating, you can see that we've got this error here of 18.8% So this is the lean area that I talked about that we're going to get when we transition into power enrichment. |
| 12:17 | This is why we can't just go all the way through to wide open throttle for all of our cells. |
| 12:22 | So what I'm going to do now, we'll do our wide open throttle run and we'll get some data in the top end of our histogram. |
| 12:56 | Alright, so we've got our run complete and right now I'm not interested in the power, I'm not really worried about that. |
| 13:00 | We're simply looking at that air fuel ratio. |
| 13:03 | We have our lambda plot shown here on our dyno. |
| 13:06 | You can see that it's a relatively straight line. |
| 13:09 | We'll remember we've set our power enrichment target to 0.85 through the entire table, so we should be targeting a fixed lambda value of 0.85 Let's drop back to our scanner now. |
| 13:23 | And, I've stopped our scanner at the end of that run. |
| 13:26 | And you can see that we've now got quite a bit of data filled in to our histogram. |
| 13:32 | Particularly under wide open throttle, we can see that anywhere that we've got green values, this means that our air fuel ratio of lambda is richer than our target and anything where we've got red values we were leaner than our target. |
| 13:45 | So for the most part, we're actually really close. |
| 13:47 | We're always within about two or 3% through this entire wide open throttle area, and if we're working with a relatively standard engine where we've got a well-developed virtual VE table, then this is exactly what we'd expect if not closer. |
| 14:03 | Of course, as we start making more drastic modifications to the engine, such as cams or heads, headwork, etc., we'll see the stock VE table become more and more inaccurate. |
| 14:16 | Now we're going to look at how we can use this data in our histogram to optimise the numbers in our VE table and reduce the error that we're currently seeing. |
| 14:26 | There are a couple of ways of doing this. |
| 14:29 | One of the most popular and probably one of the quickest is to use the paste-special function in the VCM editor. |
| 14:37 | So let's just have a quick look at how that works. |
| 14:39 | What I'm going to do is just highlight our data at the moment and copy it to the clip board. |
| 14:44 | Let's pop across to the editor. |
| 14:45 | If I right click on our VE table you can see we have the paste-special function and the two options we're going to be interested in here are multiplied by percent and multiply by percent-half. |
| 14:59 | And what these do is to apply the percentage error values from our histogram straight into our VE table. |
| 15:08 | And, essentially, if we have let's say an error of 5% in our histogram, so at a particular point in our table we, with 5% leaner than our target. |
| 15:21 | What the paste-special function will do is add 5% to that corresponding site in our VE table so that should correct our error. |
| 15:31 | The paste-by half simply does as it's name would suggest and it makes a change of half of the error, so if we had a value of 5% in our histogram, it would make a change of 2 1/2% to our VE table. |
| 15:46 | Let's go back to our scanner, though, and we'll talk about a few limitations that we need to understand with this technique. |
| 15:52 | First of all, you can see that in our histogram currently, I haven't managed to access every site in the table. |
| 16:01 | Particular if we move across to the left you can see there's this big area down here at low load that I haven't been able to get to. |
| 16:09 | Now, of course, we haven't currently gone past about 3000 RPM, and normally if we're doing this task we would try and cover as much of the engine's operating range as possible, so we would see data out here in our histogram in area I've just highlighted. |
| 16:26 | We also can see that there is an area here under high manifold pressure that we haven't accessed. |
| 16:34 | Right here, right now, our barometric pressure is quite low, so at wide open throttle we're only seeing right about 94, 95 kpa. |
| 16:43 | So we've got this area we haven't filled out and likewise at low RPM and higher load, we haven't been able to get to these areas. |
| 16:51 | So there's a few blanks in this table and if we simple use the paste-special function these aren't going to be touched. |
| 16:59 | So if we use the paste-special function we need to hand-blend our VE table in these areas where we haven't been able to get to. |
| 17:07 | And that's simply a case of copying the trends that we're seeing across into these areas we can't get to. |
| 17:15 | So, for example, how I would deal with these higher load areas. |
| 17:20 | If we have a value here of perhaps 2.5% trim that we have at 1800 RPM, sorry, at 1600 RPM and 93.8 kpa, I would simply make the same change at the higher load areas out here to the right in our histogram or in our VE table as well. |
| 17:42 | We copy the trends that we're seeing so that we get to access all of the sites in our VE table and make sure that all of the sites are being properly corrected. |
| 17:54 | Likewise, we'll deal with these areas at low RPM and high load by extrapolating the trim values, the changes that we're seeing in the areas we can get to, in this case 1200 RPM. |
| 18:07 | And we've moved those back into those areas we haven't been able to get to. |
| 18:11 | You can also see that we've got a little gap in our histogram here at 90 kpa, which sort of corresponded between my steady state testing and my wide-open throttle testing, and again we're just going to hand-blend all of those areas. |
| 18:27 | So that's one thing we need to keep in mind if we're using the paste-special function. |
| 18:31 | The other thing we need to keep in mind is that the paste-special function is simply going to copy these values and paste them into our VE table. |
| 18:41 | If we have any strange numbers in our histogram as a result of a transient situation or perhaps you saw when we first moved into power enrichment, we had a value in here of around about 18%. |
| 18:57 | So, any of those errors will will get copied into our VE table and affect the accuracy of our VE table, so we need to understand that and make sure that the data we have in our histogram is correct and sensible. |
| 19:13 | For the main part, what we're expecting to see in our histogram here is relatively smooth trends in our errors. |
| 19:22 | If we're seeing really erratic changes in our error, then this is probably an indication that we don't have good data. |
| 19:30 | And a way of checking how thoroughly we've been through this VE table, you can see we have a couple of little tabs here. |
| 19:38 | At the moment we've got the A button highlighted, which is the average value, so this shows us the average value of all of the values that were logged for a particular cell in our histogram. |
| 19:50 | We click on the C button, however, this is going to show us the count, the number of times we've accessed each of the cells in the histogram. |
| 19:59 | And obviously, the more time we've spent in each of the cells, the better the data we're going to get. |
| 20:05 | Generally, I'd like to see at least a count of 50 in each of cells we're accessing, and you can see, for the most part, that's exactly what we've got. |
| 20:14 | Obviously, if we move down to the lower load areas where we spent a little bit more time, lower RPM, lower load, you can see we've got a lot more hits in some of these cells, so the higher this value, the better the data we've got. |
| 20:29 | So if we've got any outliers or really odd values in our VE, in our histogram scan data, we do need to be a little bit careful. |
| 20:39 | The other way we can use the data from our histogram is to manually apply changes to our VE table. |
| 20:45 | Now this is a lot more time consuming but it does allow us the freedom to get around any outliers in our data, any odd data points that simply don't make sense or aren't realistic. |
| 20:56 | So here what we would be doing is looking at an RPM row in our histogram, and looking for trends in that data. |
| 21:05 | So, for example, let's just look at our 2400 RPM row for start. |
| 21:12 | And you can see, let's move all the way across to the left. |
| 21:17 | You can see that from 23.4 kpa and 26.3 kpa we've got an error of around about 4 1/2 to 5%. |
| 21:29 | Now, we haven't been able to get out to these areas down here to the left, so what I would start by doing is applying a change here all the way from 15 kpa to 26.3 kpa. |
| 21:43 | So what we're going to do is highlight our 2400 RPM row and we're going out to 26.3 kpa. |
| 21:50 | And remember, we're going to make a change of 4 1/2%. |
| 21:53 | We're going to be adding 4% because our measured air fuel ratio was leaner than our target. |
| 21:59 | And we can do that by multiplying these values by 1.04. |
| 22:05 | No, actually, 1.045. |
| 22:07 | That will add 4 1/2% to these values and we can press multiply. |
| 22:12 | So that's corrected that particular set of cells. |
| 22:16 | Now, if we look at the rest of our data, between 29.1 kpa and 34.7 kpa, you can see we're around about 5 1/2%, so let's make that change. |
| 22:29 | So we're going out this time to 34.7 kpa. |
| 22:33 | So we'll highlight those particular cells, 34.7 kpa, this time we want to make a change of five and a half percent, so we'll click multiply again. |
| 22:43 | If we look at our data, we can see at 37 1/2, we want to make a change of four, then let's say 3 1/2 and then 3%. |
| 22:54 | So I'll make those changes now. |
| 22:57 | So we want to make a change of four, and then 3 1/2, and then we want to make a change of three to our 43.1 kpa site because that's corrected our 2400 RPM right out 43.1 kpa. |
| 23:19 | Let's go back to the scanner and now we're looking at our 45.9 kpa. |
| 23:28 | We're about 2 1/2% and about 1 1/2% for our next two cells, so 2 1/2 and then 1 1/2, let's make those changes. |
| 23:37 | So we're into 2.5, and then 1.5. |
| 23:45 | So again we're just looking for an approximate trend here, we're not trying to be percentage perfect here. |
| 23:51 | So we're now out to 54.4 kpa and you can see here our changes a little bit less. |
| 23:58 | Now, we're sitting around about half a percent out to 65.6, so let's make that change now. |
| 24:06 | So we're going out 65.6 and this time zero, zero five and it's going to make half a percent change, so we're talking very small changes now. |
| 24:16 | And I'm not really going to worry about these areas through here, we are at errors point one, point two we're so close. |
| 24:25 | However, when we get all the way out to wide open throttle, you can see that now we have an error of 2 1/2% in this case. |
| 24:35 | We need to remove some fuel. |
| 24:37 | What I'm going to do is make this change from 90 kpa and above and we're going to remove 2.5% and to do that, we need to multiply our value by 0.975, that will remove 2 1/2%. |
| 24:58 | And remember, as I mentioned, I've copied that error out to the value so that in the table, the map values that we haven't been able to get to. |
| 25:06 | So that's the process of manually adjusting of the table. |
| 25:10 | As you can see, it is a reasonably time-consuming process but it does give us a little bit more control over how the changes are going to be made, and particularly if you're doing your scanning and tuning on the road, it's likely that you're going to end up with some points in that scan data, in that histogram that aren't necessarily in line with the surrounding cells. |
| 25:34 | I'm just going to undo those changes because for the purposes of this demonstration we're going to actually use the special-paste function. |
| 25:43 | So we'll come back to our histogram and I'm going to right click on our histogram data. |
| 25:49 | And I'm going to press control-C and then we're going to come across to our VE table and I'm going right-click and now we go down to our paste-special. |
| 26:02 | Now, we have two options here as we've talked about, we can paste the entire error directly into our VE table or we can multiply our values at error by half, so this makes a smaller change. |
| 26:15 | Generally, if we've got a large error, so if I'm seeing an error of perhaps five to 10% or greater, I would generally start by using the multiply by percent, so applying the full error. |
| 26:30 | This is an iterative process, we're not going to correct all of our errors in one shot, so we do need to come back and have another go at this, perhaps two or three attempts. |
| 26:39 | Once that error gets a little bit closer, again to help remove any inconsistencies with our histogram, I tend to use the multiply by percent half, just to allow us to creep up a little bit slower and a little bit more accurately on our error. |
| 26:55 | I'll just talk about our actual error as well, because it's important to understand what we are aiming for. |
| 27:01 | Now, in the perfect world we'd like to see our error and our histogram sitting at zero. |
| 27:06 | This isn't realistic. |
| 27:07 | We're never going to see an error of zero throughout our entire histogram. |
| 27:12 | And what we want to do is simply get it as close to zero as possible. |
| 27:16 | It should be possible to get our error within around about one or two percent. |
| 27:21 | It really depends on how fussy you want to be and how much time you have available. |
| 27:25 | But certainly you don't need to beat yourself up trying to get an absolutely perfect zero. |
| 27:31 | Personally, I tend to aim for a negative error in my histogram, which simply means that our measured air fuel ratio is slightly richer than our target. |
| 27:41 | It's always safer to be slightly rich than it is to be slightly lean. |
| 27:46 | So let's start now by multiply by half, so it's going to make it a half percent change to our table there. |
| 27:56 | And then I'm going to simply go through now and copy that error out into these areas which we haven't been able to get to. |
| 28:06 | So we have a complete table when we actually start the engine, and start trying our next test. |
| 28:14 | So let's go through that process now. |
| 28:16 | You can watch me do that. |
| 28:29 | Alright, we've gone through and hand blended and what again I've been doing there is just simply looking at the trends we've got going on in our histogram and we don't need to be 100% critical here. |
| 28:40 | We're not trying to chase every individual cell, we're just looking for trends. |
| 28:45 | Remember, we're not going to be able to get our error to a perfect zero and we do have our close loop fuel trims available when we're operating closed loop once we've got our calibration complete and we enable the close loop system again. |
| 28:59 | And that's going to be there to correct for any small errors we still have remaining. |
| 29:03 | So now let's have a look at the shape of our VE curve, and again, if we've done our job correctly, we should still have a reasonably smooth shape to our VE table. |
| 29:15 | We're starting to get a really erratic shape to this table and again that's indicative that we've got some problems with the data in our histogram. |
| 29:24 | Once we've completed the modifications to our VE table, we need to now copy this data into our other two VE tables, and we can do that by highlighting the entire table, using the control-C function. |
| 29:38 | And then simply opening our other two tables and using the control-V function to paste these changes. |
| 29:47 | Right, we're now going to flash our first change into the PCM and we'll test again and see if we've improved the accuracy of the VE table. |
| 29:59 | Right, we've got our engine back up and running. |
| 30:00 | I've got the scanner operating. |
| 30:02 | And the other process is simply to drive back through all of the cells in our histogram hitting as many as we can and logging a new error. |
| 30:11 | Now, if we've done our job correctly, what we're going to find is our errors this time around are going to be much closer to zero than our first attempt. |
| 30:19 | And we can see right now on our scanner the 1200 RPM row that I'm currently accessing we've got errors of less than half a percent, so that's all looking pretty promising. |
| 30:30 | Now this can take a few attempts, as I've mentioned. |
| 30:32 | It is an iterative process, so we do need to be patient and take our time doing this. |
| 30:37 | We can chip away and end up getting our errors very close to zero. |
| 30:42 | So, the quick snapshot that we've looked at there at 1200 RPM, we can see that the results of our first round of modifications to our VE table have, in fact, worked well. |
| 30:55 | We're much closer to our zero point. |
| 30:58 | I'll just continue moving through our 1200 RPM column, our 1200 RPM row so we can see a little bit more data here. |
| 31:08 | And we can see there's still a little bit of a positive error down at our lower manifold pressures but again, we're much closer than we were on our first attempt. |
| 31:18 | So I'm not going to go through a complete process of looking at all of our data again. |
| 31:23 | If we're doing the job correctly, and everything's working as we expect, we should find that after each change we chip away and get a little bit closer to a zero error. |
| 31:34 | Remember, we used a histogram in two ways. |
| 31:37 | We ran the current steady state, where we were replicating idle and cruise conditions. |
| 31:43 | We also did some wide open throttle ramp runs to look at the accuracy of our VE table under power enrichment. |
| 31:51 | So let's do that now, and we'll have a look at another wide open throttle ramp run and see if we're a little bit closer to the mark this time around. |
| 31:58 | Right, we're already on the dyno so I'll start our scanner and we can begin our run. |
| 32:27 | Alright, so we've completed our run and we can see our power and, power and air fuel ratio being displayed on the dyno. |
| 32:35 | However, let's have a look at our scanner because our histogram is really what we're interested in here. |
| 32:41 | And you can see, again, we still have some minor errors but this time we're all much closer to zero and, in fact, the largest error we have is right up at the top of our run. |
| 32:53 | We've got an error of negative 1.37, which means that we were 1.37% richer than our target. |
| 33:01 | You'll remember that in our first attempt, particularly these high RPM areas of our histogram, we actually had a positive error, which meant we were a little lean. |
| 33:11 | So you can see that, for the most part, throughout that run our errors generally were within plus or minus .5 of a percent, so we're very, very close to our target. |
| 33:21 | Again, we can chip away at this further. |
| 33:24 | We're only going to perform one iteration of our changes after this particular demonstration. |
| 33:29 | The process is just to simply rinse and repeat the same process until we get our error where we want it to be. |
| 33:37 | Alright, we're going to move on now and we're going to look at what we do once we've actually got our VE tables dialled and where we want them. |
| 33:47 | So, remember, one of our first steps was to put the PCM into open loop mode. |
| 33:53 | So it was -ignoring both or short-term and our long-term fuel trims. |
| 33:58 | And now the process is going to be to revert that and we're going to put our PCM back into closed loop mode, once we've gone through and completed optimising our VE table. |
| 34:09 | So let's go trough that process now. |
| 34:12 | You'll remember that we had made quite a few changes to a variety of tables in order to force a constant lambda target of 1.0 in our open loop mode, and we need to revert all of those tables. |
| 34:26 | Get them back to the factory settings and the easiest way of doing this is to load up our base file as a Compare file and then we can see what the original settings were and we can copy them back into our new speed density calibration. |
| 34:40 | So let's do that now. |
| 34:42 | If we go to our Compare tab and what we're going to do now is open our base file as our Compare file. |
| 34:49 | Now what you can see is anything that where we have a difference between our current file and our new file is going to be highlighted so you can see that now. |
| 34:59 | What we're going to do is flip across to our fuel tab and we're going to go to our open and closed loop tab here. |
| 35:08 | So we can see all of the tables that we've previously changed. |
| 35:13 | Now let's go through and we'll see how we can use the Compare function to easily copy our original data back in. |
| 35:21 | We have our options here. |
| 35:22 | We can show our main table, which is our left icons just our main calibration. |
| 35:28 | If we look at the centre icon here, this will show the Compare files, so this will show the data out of the Compare file we just loaded up and if I click on there we can see that data become visible. |
| 35:41 | We can also show the differences between the base file and the Compare file. |
| 35:46 | What I'm going to do here is simply click on our Compare file. |
| 35:50 | And if we click on the left top corner to highlight the entire table, we can either use our copy icon here, or control and C to copy that. |
| 35:59 | We then click back into our main our main table, our main file and we can paste that data into our main file. |
| 36:11 | Then, once we've done that, we can close that down and you can see that that particular table goes red to indicate we've made a change there. |
| 36:20 | We're going to go through this process for all of our various tables that we've altered to put the engine into both open loop as well as to make sure that we're always chasing a consistent lambda target when we're operating in open loop mode. |
| 36:39 | So we'll just go through each of these in turn. |
| 36:42 | Whether you like to use the control-C and control-V keyboard shortcut or you prefer to use the copy and paste icons is really up to you. |
| 36:52 | I find the keyboard shortcuts are a little bit quicker when I'm making multiple changes like this. |
| 36:59 | So we've got our last table here that we're going to change. |
| 37:03 | So that's taken care of, of our open loop lambda targets and gains. |
| 37:09 | Now, remember we also disabled our short-term fuel trims and we can re-enable these here. |
| 37:15 | Again, I'm just going to copy our original settings and paste them into our new file, speed density calibration, and that's going to re-enable our short term fuel trims. |
| 37:30 | Okay, so we'll close that down now. |
| 37:32 | Now, at the moment, you can see we also have our long-term fuel trims and the long-term fuel trim enable parameters I've got set here will leave our long-term fuel-trims disabled. |
| 37:43 | They're not going to do anything. |
| 37:45 | And this is a personal preference aspect, really. |
| 37:49 | Personally, I prefer to leave the long-term fuel trims disabled and the reason I do this is I know this way that our long term fuel trims aren't going to end up affecting our air fuel ratio under open loop and I personally like to know that what I've got on the dyno when I'm tuning in open loop is what I'm going to end up with and we're not going to see those air fuel ratios affected out on the road or the race track by our long term fuel trims once they've updated and stabilised. |
| 38:21 | Many tuners on the other hand will leave the long term fuel trims active. |
| 38:24 | It is totally up to you. |
| 38:27 | And I'd suggest trying both options and seeing which you prefer. |
| 38:32 | Remember, though leaving the long term fuel trims disabled doesn't mean that we have no fuel trims active. |
| 38:39 | We still have our short term fuel trims, which work instantaneously on any error that we have between our commanded lambda and our measured air fuel ratio. |
| 38:49 | So I'm personally going to just leave these disabled and we're going to rely solely on our short term fuel trims. |
| 38:58 | The next aspect that we need to re-enable is our deceleration fuel cut off, so we'll come across to our deceleration fuel cut off tab and again we can see the tables. |
| 39:08 | The parameters that we've changed are highlighted here in green. |
| 39:13 | So we can look at our original calibration, our base calibration, again using the icons up here, the main, the Compare file and the difference. |
| 39:22 | And what we want to do is simply copy these parameters from our original file across into our new file. |
| 39:32 | So, we're going to just take note of these. |
| 39:35 | We've got 30 degrees, 25 degrees, and then 1100 and 1200 RPM. |
| 39:40 | And I'm just going to make those changes. |
| 39:44 | 25 degrees, we've got 1100 and then 1200 RPM. |
| 39:49 | So that's going to re-enable our deceleration fuel cut off. |
| 39:53 | So at this point we've calibrated correctly our VE tables. |
| 39:57 | We know we've got accurate control over our air fuel ratio and it's matching out commanded air fuel ratio. |
| 40:03 | We've re-enabled our close loop control, and we've got our short-term fuel trims active in this particular calibration. |
| 40:11 | We've also re-enabled our deceleration fuel cut off. |
| 40:14 | So I've essentially got our ROM file ready to go and we're ready to move on to our next step. |
