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Practical Reflash Tuning: Step 3: Configure Base Tune File

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Step 3: Configure Base Tune File

13.46

00:00 - In the third step of our process, we're going to go through the job of configuring our base calibration before we flash it into the ECU.
00:07 And of course at this point because we are working from that off the shelf map, a lot of the heavy lifting there has been done for us.
00:13 There are still a few aspects that I just want to cover off though so let's get started by opening our Accesstuner software.
00:25 When the Accesstuner software opens we can select the vehicle that we're going to be tuning, in this case we know we are dealing with a U.S. domestic market 2015 manual transmission Subaru WRX.
00:36 I've also got the option of the tuning strategy, in this case we are going to be using the latest tuning strategy available and then we can select the map that we're going to be using by clicking on the load map button.
00:49 If you are dealing with an existing calibration that you've been working on any time you open the software, it will automatically load up the last map that you were dealing with.
00:58 In this case we'll click on load map and we can load up the map that we're interested in working with.
01:04 Once this is loaded up we'll have access to all of the maps and we can work our way through the system.
01:10 The Cobb Accesstuner software is relatively user friendly and intuitive to work through.
01:16 We've got all of the available tables listed up here in a menu structure.
01:20 And for example here at the top we've got all of our real time tuning tables.
01:24 And we are going to be making use of the real time tuning feature in the Cobb software a lot during this worked example.
01:31 While it is a little unusual to be able to live tune when we are reflashing a factory ECU, where we do have that ability, it can speed up the process considerably.
01:41 So we can see here there are a reasonably large list of tables that are available there for live tuning, certainly not all of the tables.
01:49 But the main workflow that we're going to be going through when we are tuning, we're going to be dealing with our mass airflow sensor calibration which we can see here.
01:58 That's one of our key inputs that we're going to need to tune as we've already discussed, and we can see that that is live tunable which is quite helpful.
02:05 If we move up, we've also got our closed loop fueling, our air/fuel ratio targets, these are also live tunable.
02:12 And you can see when I open a three dimensional table like this, we've got the table shows up numerically up here on the top right and then we also have a graphical display of that table just so we can get a sense of the shape of that table and if we click on the three dimensional table and hold down our left mouse button and move it around, we can move those axes around so we can better see what we're dealing with.
02:35 The other key tables that we're going to be dealing with during our tuning that are available in live tuning, we've got our primary ignition with our tumble generator valves open.
02:45 We've also got our boost target table up here which we're going to be making adjustments to if we want to adjust the boost targets.
02:52 And then in conjunction with that, down the bottom we've got our wastegate duty cycle high and low tables which are quite likely going to need some manipulation in order to get our boost control on point.
03:04 While we're setting up our software it's also important to make sure that we've got some of the key parameters that we're going to need to keep an eye on, visible in a gauge format as well as making sure that we're logging all of the key parameters that we're going to need in order to help us fine tune our calibration as we move through that process.
03:23 We can adjust these parameters by going to our edit menu.
03:26 If we click on that, we can move down and we can click on configure options here.
03:31 Or alternatively you can use the hot key control plus F, so let's click on that.
03:36 That'll open up our configure window.
03:40 Now there's a lot of information available here.
03:43 Really we're going to be interested first of all in our gaugeless tab.
03:47 So this adjusts the parameters or channels that are available as a gauge which we can view while we are tuning.
03:54 I've already selected some of the key ones that we're going to want to look at.
03:58 In particular we've got our A/F correction #1 which is our short term fuel trim and our A/F Learning #1 which is our long term fuel trim.
04:06 We've also got our air/fuel ratio coming from the wideband air/fuel ratio sensor on the factory ECU.
04:13 This is quite powerful here because the WRX is fitted with a wideband sensor from stock.
04:20 It's proven to be fairly accurate so we can actually rely on this for our tuning, it means that we don't need to bring an external wideband air/fuel ratio meter into the scanner software while we are doing our tuning.
04:31 Moving down, we've also got our calculated load so we know where abouts we are inside of our tables.
04:38 We've got our closed loop and open loop switch just so we know whether the ECU is operating in open or closed loop.
04:44 We've got our commanded fuel or air/fuel ratio final.
04:48 We've also got our coolant temperature just so we can keep an eye on what our coolant temperature is doing.
04:54 Our dynamic advance multiplier, we're going to talk a little bit more about what this is and how it works as we get through the tuning, but essentially a key part of the ignition strategy inside of the Subaru ECU.
05:06 Of course we've got our engine speed, another key input that we're going to need.
05:11 And in terms of our ignition tuning, we've got our feedback knock correction as well as our fine knock learning which will give us input on the knock feedback or what's happening and the activity from the knock control subsystem.
05:23 We've got our injector timing which is relatively important with a direct injected engine.
05:29 We've also got fuel pressure information there and gear position.
05:33 Ignition timing obviously critical there.
05:35 We've got our intake air temperature, some more knock information here, or knock per cylinder data.
05:42 And we've got our manifold absolute pressure as well as our manifold relative pressure.
05:48 So this is just a absolute pressure versus a gauge pressure inside of the inlet manifold.
05:54 We've got our mass airflow sensor voltage which is important because this is the input to the ECU from the mass airflow sensor, key when we are optimising our mass airflow sensor scaling.
06:07 We've got our requested torque, this is an input on one of the axes on a number of the tables, particularly boost control for example, so it's important so we know where abouts we are in those boost control tables.
06:18 Moving on we've got throttle position as well as our turbo dynamics, just so we know what our boost control strategy is doing, and included with that is our wastegate duty cycle.
06:31 So these may not be the only parameters or channels that you want to log but this is a fairly extensive list that's going to give us pretty good indication of how the engine's operating.
06:40 Certainly the key pieces of information we need when it comes to tuning.
06:43 Now that's our gauge list, so this displays on our laptop software while we're tuning.
06:48 If we look at our next tab over which is our log list, essentially looks identical and this is the parameters that we are going to be logging.
06:56 And it is important here as well just to mention that we don't want to log every single parameter because this can slow down the logging process.
07:04 So we really want to choose the key aspects that we're interested in.
07:08 If we just click back on our gauge list, you'll also see that once we've selected those we can click on the copy to log button and that will copy everything across to our log list, just meaning that you don't need to double up on that process.
07:22 Likewise if we are on the log list, we can copy these across to the gauge list.
07:27 Once we're happy with our selection for our gauges and our log list, we can simply close down that window and commit those changes.
07:35 Now as I've already mentioned, most of our setup here has already been done because we are dealing with this off the shelf map so the key amongst those is that we already have a MAF scaling that should suit our new Cobb intake system.
07:48 So we should be able to get our engine up and running relatively easily.
07:51 However there are a couple of remaining changes that I do still want to make.
07:56 Once of the key changes is to make the ECU run continuously in closed loop mode.
08:02 That's not how the factory Subaru ECU works, it operates as most factory ECUs do where it'll run in closed loop mode at idle, cruise and under moderate load and then once we go to high load it'll transfer into open loop mode where it's commanding a specific air/fuel ratio but if there is a difference between the target air/fuel ratio and the measured air/fuel ratio, the ECU's not going to do anything to try and combat that.
08:27 So it's been proven by Cobb that the closed loop control system on the Subaru WRX actually works exceptionally well.
08:35 It's very quick and it's reliable so there's really no downsides in running it in closed loop and this just means that if there is any day to day variation in the atmospheric conditions or anything in the car operation that means the air/fuel ratio doesn't quite match our target, the ECU is able to add or subtract fuel until it's right on our target air/fuel ratio.
08:56 I do want to mention here that this is not a bandaid for properly tuning the ECU in the first place.
09:03 This is really there as a safety backstop in case something isn't quite right.
09:06 So it's not an excuse to not do your job properly, it just gives you the confidence that once the ECU is properly tuned it is going to stay on that target air/fuel ratio.
09:17 Now rather than going through each of the individual steps which is quite time consuming, in order to force the ECU into continuous closed loop mode, what I want to do is show you the process that you'll go through and how to find that information.
09:31 So let's head to our browser and we're on the Cobb main page of their website at the moment and what we want to do is click on support.
09:40 Once the support page is loaded, we want to come down to our Subaru Accesstuner support and we'll click on that.
09:48 Once this page is loaded up, what we're going to do is choose our Accesstuner help file and the one that we're interested in here is our Subaru Accesstuner DIT tuning guide supplement.
10:01 So we'll click on that and there is a lot of information here which as a matter of course you should familiarise yourself with anyway.
10:08 But the aspect that we're interested in here is our closed loop tuning, closed loop fuel tuning.
10:15 So we'll just cycle down until we get to the area that discusses how to force full time closed loop control.
10:23 So as you can see here, there's some fairly detailed instructions showing you exactly which tables you need to access, where you'll find each of those tables and what sort of numbers you need to input into them.
10:35 For example, in this particular instruction here we can see that we need to go to the fuel tables, closed to open loop transition delay table group and then set the delay values in the closed to open loop delays table to 65,535 across the entire table.
10:53 Now again I'm not going to go through each of these steps, it's just more important to understand where you'll find that information in order to follow that through from start to finish.
11:02 And again this will force the ECU to run continuously in closed loop mode, meaning that if there's any error between the target air/fuel ratio and the measured air/fuel ratio from the wideband sensor in the exhaust, then the ECU is able to add or subtract fuel via the short term and long term fuel trims in order to correct that error.
11:23 Since we have just been talking about air/fuel ratio, this is a good time to check out our closed loop fuelling target base table and have a look at the air/fuel ratio targets that are in there.
11:34 Now I am representing these here as lambda however if you prefer to work in air/fuel ratio units you can choose to do so.
11:41 So here we can see our air/fuel ratio or lambda targets versus load and engine RPM.
11:47 And we can see at the moment that these are set particularly in the boost areas of the table to be relatively conservative, starting around about 0.80 at lower RPM before moving quite rich at high RPM and load down to around about 0.74.
12:05 Now we are going to be able to adjust these air/fuel ratio targets as we start tuning the engine and we can of course try richer or leaner targets and see how the engine responds.
12:16 In general it's been well proven that the FA20 DIT engine does actually respond pretty well to running a little bit richer, particularly under high load.
12:24 The reason for this is it does tend to be quite knock sensitive, particularly on pump fuel.
12:30 And in order to get good results out of this engine, it seems to respond better to using a richer air/fuel ratio in order to reduce our combustion temperature, that moves the engine away from knock, the knock threshold allowing a little bit more ignition timing to be added in.
12:46 So you're going to potentially, or most likely see an improvement in engine power overall by running a richer mixture, allowing a little bit more timing.
12:54 At this point we've made the key changes to our calibration that we needed to make, while this of course isn't going to be the final iteration of our map, we now have a calibration that should be good enough to flash into the ECU, get us up and running safely so that we can start gathering some data and fine tune that calibration.
13:14 What we want to do now is save the calibration, we can do that by going to the file menu in the top left corner and we want to click on save Accessport map.
13:23 Alternatively you can use alt + ctrl + S as a shortcut hot key.