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Practical Reflash Tuning: Step 1: Downloading Stock ROM

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Step 1: Downloading Stock ROM

07.06

00:00 - The first step of our process involves reading the stock ROM file out of the ECU.
00:05 We need to this because we are going to be working from that stock ROM file while we're making our modifications.
00:11 It's also an important first step because we want to save that stock ROM file with a specific name so that we've got it there safe and sound if we ever need to revert to it at a later point.
00:23 In order to do this, we're going to need our EcuFlash software open, I've already got that done.
00:29 And there is also a hardware interface, in this case we use the Tactrix 2.0 cable, this plugs in at one end to our OBDII port on our car, the other end plugs into the USB port on our laptop so that's our interface between the software and the car itself.
00:46 When we are reading and writing from a Subaru vehicle we also need to connect, in the case of our version 11 STi, the green two pin flash connector that you'll find in the passenger's footwell near to the ECU.
01:00 Now if you are dealing with an earlier model car, an earlier model Subaru vehicle, there are a couple of alternative flash connectors that you may also need to connect and you'll find that when you're ordering your Tactrix cable, they have the options available to order the flash connectors with that cable so you'll have them there, they're very cheap and cost effective so no reason not to grab all of those that are available, this will cover you for any vehicles you want to flash in the future.
01:28 So what we're going to do is start by clicking on the little read icon in the top of the toolbar, this opens up a little box and we just simply follow the instructions on that box.
01:38 I've found it can be quite sensitive with EcuFlash, the timing between you actually turning the ignition on and pressing OK and this goes for both reading and writing.
01:47 Generally what we want to do is time that quite carefully, so we're pressing OK, essentially as soon as we've got the ignition into the run position.
01:55 So let's go ahead and do that now.
02:00 Once our read is complete we'll see a little box pops up showing us that that has read successfully and we can shut the car back off.
02:07 We can now click OK and this is the time where we get to see if we do in fact have a definition for this particular ECU ROM and in this case we do, a box would pop up telling us that the ECU ROM file is not defined if that was the case.
02:23 We can see that over on the left hand side here we've got all of our menu structure.
02:28 If we click at the top here on our ROM info we can find out all about the particular vehicle we are flashing, in this case we can see that it is an '09 Japanese domestic market Subaru STi and the specific part of the ROM file that's important as an identifier is this internal ID, in this case we can see that the ROM file is an AZ1G500F.
02:54 Now this is important, if it happens to pass that, you don't have a definition because you would be wanting to find a definition for that particular ROM ID.
03:03 And while this can be a little bit tricky and is beyond the scope of our worked example, on some of the larger Subaru enthusiast forums you may be able to find the specific definition that you need if you don't have one.
03:17 However in this case, we know we've got one so we can carry on.
03:21 Even when we have got a definition you're going to always want to check and just have a look at a few of the tables and make sure that they make sense.
03:28 First of all what we can see here in the menu structure is we've got some tables like this one here for our target boost, which is in a dark black.
03:38 This means we've got a defined table here and if we click on this we'll be able to see that it should make sense.
03:43 We can see we've got a 3D table, we've got our engine RPM on our vertical axis, we've also got our requested torque which comes from the ECU on our horizontal axis and the numbers inside of this table here are actual boost targets in terms of PSI.
03:58 So this table makes sense, everything's as we would expect.
04:03 It's always a good sanity check, even if your ECU is defined, just to make sure that a few of the tables you look through, all of the numbers are what you'd expect.
04:11 If it wasn't defined you'd find that the numbers in both the break points of our axes as well as the table itself are probably just absolute nonsense.
04:19 We can close that down, these other tables here which are greyed out, these are potential tables that in this particular ROM are not defined, this means that they don't exist, we can't edit them.
04:31 That's not a problem, when we reload this, we're going to get rid of those so everything is a little bit cleaner and tidier.
04:37 But this definition that we do have gives us enough information to work with.
04:40 We've got all of the key tables defined that we're going to need to adjust.
04:44 And we can open and close the menu structure as we go through.
04:49 Let's just have a look at another table where we will be spending a bit of our time which is in our primary open loop fuelling table.
04:56 So this is our target air/fuel ratio, so again we'll open this, we can see that it all makes sense, the break points for our axes are sensible and the target air/fuel ratios in there are also sensible.
05:07 You can see though that in stock form the Subaru air/fuel ratio targets are incredibly rich and that's something we're going to be addressing as we go through the tuning process.
05:17 So at this point I'm happy that our ECU is defined, the definition is accurate so what we're going to do now is save that and we can do this using the little save icon up here in the toolbar.
05:32 When we're saving our ROM file we want to use a sensible name so it's going to be easy to come back and find that later and it's totally up to you how you do this.
05:42 I just suggest that you choose a method where you can apply some consistency.
05:46 What I'm going to do here is start by using the registration of this particular vehicle and then we'll also put in the make and model of car and then I'm also going to add a little identifier to the end of that which is stock, so this just lets me know at a later point that I'm looking at the stock file.
06:07 And again, important because we've now got that saved, we can come back to it at a later point.
06:12 This is also a good place to save our file again with a separate name and this makes sure that we don't accidentally end up making modifications to our stock file.
06:21 We can do that by coming up to our file menu and we're going to click now on save ROM as.
06:28 And all I'm going to do is just remove that stock identifier and we'll call this tuned.
06:33 And again, you could call this whatever you want, maybe you want to make some notes here about the type of fuel or a couple of notes about the specification for the vehicle.
06:42 All you're really trying to do here is give yourself something that at a later point, you can jog your memory and you know what that particular file was.