Practical Reflash Tuning: Step 3: Configuring Base Tune File
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Step 3: Configuring Base Tune File
24.53
| 00:00 | - So at this point, we've taken a quick look, we've weeded out a number of tables, functions, systems of logic which don't have an impact on what we're doing. |
| 00:08 | Let's start talking about what adjustments we do need to make. |
| 00:11 | I'm going to go into the engine, fuel, temperature control section and let's just have a quick chat about catalyst protection. |
| 00:22 | So in the past this was something that a number of people would adjust on various vehicles and in the case of this vehicle we have here today, we have stock catalysts, we have stock entire exhaust, in my opinion we have no reason to adjust this because it's already been set up in a manner that it will allow maximum performance as well as maximum reliability of the catalyst. |
| 00:47 | Now if you have swapped a GM Gen V motor into a tube chassis drag car and you don't have catalysts, of course you're going to want to disable this and if you have a setup that's somewhere in between, like perhaps a road race vehicle, which is again race only but does have high flow catalysts, it's very possible that you'll need to adjust rather than disable these functions in order to get a combination of best performance, control over your fuelling strategy, getting exactly the air/fuel ratio you expect, as well as retaining the reliability of those high flow cats. |
| 01:28 | So what the system effectively does is it attempts to cool down the catalysts by applying additional fuel enrichment. |
| 01:35 | And in this case it looks like a maximum enrichment of an EQ ratio of 1.2 or an addition of about 20% is the max range, with a minimum of a 3% addition in fuel. |
| 01:53 | Under the engine diag section, under the airflow tab, we have some various items related to the mass airflow sensor. |
| 02:02 | So we have a MAF frequency fail high item and in some cases you may be in a situation where you've increased the airflow of the engine or you've changed out the intake system to one that allows you to achieve very high mass airflow, and the frequency is getting high enough that you have exceeded this value here but not necessarily gone outside of the total range of the sensor. |
| 02:31 | So in some cases you may need to bump this up slightly, say to maybe 15,000 Hz from 14,500. |
| 02:40 | I would caution you though, you don't want to set this higher than what's physically possible for the sensor to read or you might avoid this very important error checking that is something that's good to have so I'm just going to go ahead and set that back. |
| 02:55 | If we find out during the tuning process that I need to bump it up then I will but that's not something that I change unless I absolutely have to. |
| 03:04 | Another item in this section is the airflow correlation section. |
| 03:09 | So what this refers to is when airflow is not as expected and expected relates to the models within the ECU. |
| 03:21 | So for example, if your MAF scaling isn't quite spot on or you end up in simply a transient situation, where your MAF scaling's correct but the MAF doesn't necessarily perfectly represent the airflow that's actually happening in the motor, you can end up in a situation where the ECU thinks something's wrong, either a leak or something of that nature and in order to avoid that potentially causing an issue, causing a DTC during your tuning process, what you might want to do is get in here to the airflow delta section and just give yourself a little margin of error here so I'm just going to add 10% here. |
| 04:06 | By multiplying by 1.1. |
| 04:09 | I'm also going to do that in the MAP delta section. |
| 04:17 | And you'll notice on the top end, the values were already just about maxed out, now they are. |
| 04:25 | Next if we go to max airflow, take a look at these values, seems like quite a lot of air, I don't think we're going to be running into this so I'm going to leave this alone. |
| 04:39 | And then if during the tuning process we find that we're actually exceeding any of these limits, we can always come back and bump it up. |
| 04:46 | So as much as I like to adjust things up front and have the tune as prepared as possible before getting on the dyno, if I'm not sure I need to adjust something, just wait until later, you can always do it then. |
| 04:59 | And then here, max airflow vs ignition. |
| 05:05 | It looks like at the voltages I expect to see, we'll be well under this limit as well so we're going to leave that one alone. |
| 05:14 | So after saving those changes, let's go back to the engine section. |
| 05:21 | Under airflow, and this is where we find the MAF calibration. |
| 05:29 | Now if you're in a situation where you've changed the intake and you're aware of the disparity between its MAF housing diameter vs stock, you can go in here and make a change across the board right up front. |
| 05:44 | The MAF intake that we're dealing with today is actually meant to replicate stock pretty well, the MAF diameter's not significantly different so I'm not going to get into this at this point but again, let's say your MAF diameter is 5% larger than stock, you could go in here and make an appropriate adjustment to get you off on the right foot when you start the car up. |
| 06:07 | Next under the fuel section, under lean fuel saving, we're going to see the displacement on demand section, also known as AFM or advanced fuel management on a GM Gen V. |
| 06:19 | This section here relates to cylinder deactivation under certain conditions. |
| 06:27 | Because this is a street car and the engine is stock, we're going to leave it enabled. |
| 06:31 | If you are in a race only application for an offroad vehicle, you may find it useful to disable this, so just want to make sure we cover it today but on a street vehicle, this is great to help you get some extra miles per gallon, might as well leave it on. |
| 06:46 | Now let's get into the torque management section. |
| 06:49 | Now some folks like to come into the torque management section and simply max everything out. |
| 06:56 | What I'm going to suggest is a little bit more careful approach of only manipulating torque management as needed to get the desired effect. |
| 07:05 | So on these new torque based ECUs, I really suggest allowing just a bit more torque than you're making. |
| 07:12 | In most cases, and we'll get into this in more detail when we're datalogging the car, you're going to want to request about 100 foot pounds more than you're actually making and I've come up with that value based on logging the factory vehicle various different GM Gen Vs and finding that that's essentially what they're doing in stock form and as you start to get closer and closer to the peak value allowed, you start to get throttle intervention where the throttle starts to close during a wide open throttle attempt. |
| 07:42 | So for now, let's just look over what we have here. |
| 07:47 | Again we see that the RPM vs gear table is fully maxed out but there are some very important tables which are carefully tuned. |
| 07:55 | And one of them's going to be the peak engine torque table. |
| 07:58 | So like I mentioned, this is one you're going to want to set, so you've got a buffer of let's say 100 or a little more foot pounds greater than what the engine is monitored as actually making built in. |
| 08:11 | And besides that, we see a few other options here, oil starve, generally speaking you're going to leave that on. |
| 08:21 | Wheel hop control though, power hop, if you're someone who likes to go to the drag strip or simply wants to launch the car very aggressively, this system might hamper your fun so if you're willing to take the chance on removing a safety system that can potentially protect your rear axles for example, you can just go ahead and click this off. |
| 08:41 | And for this customer, just in case he wants to do a burnout, we're going to disable that one and go ahead and save again. |
| 08:49 | Next let's talk about a series of changes which we don't need to make on this particular vehicle but may be of use to you and your project. |
| 08:57 | In the airflow general section, we find the MAP sensor configuration. |
| 09:01 | Now on this vehicle, we're using the factory sensor, we've not altered it but perhaps on your application, you have a naturally aspirated engine and have fitted a supercharger. |
| 09:10 | In that case, you might actually end up swapping in the sensor from this vehicle. |
| 09:16 | So you would go in here and change from an NA MAP sensor to an NA MAP sensor that also has temperature or this supercharger sensor which has both manifold temperature and pressure. |
| 09:29 | Or perhaps you've changed something more significant like perhaps the bottom end. |
| 09:33 | If you've gone and overbored the motor or swapping in a different block with greater displacement, it's really critical that you update the cylinder volume here. |
| 09:42 | So this function ties into airflow calculation through the SD function, the virtual VE system, torque management, it impacts a great number of things so absolutely critical that this value is always correct. |
| 09:56 | While swapping injectors is far more common on a port injected application, there are aftermarket DI injectors available so if you go to the fuel, general section, you'll find a series of settings all related to fitting aftermarket injectors. |
| 10:12 | You'll find flow rate, minimum pulse widths, offset profiles, short pulse adders, as well as drive parameters for the electrical side of things. |
| 10:23 | So quite a bit of information here, really critical that you work with a supplier who's able to give you all the data required. |
| 10:31 | Just like on the port injection side where we have Injector Dynamics able to fully characterise things. |
| 10:37 | Really really critical on the DI side too so be sure to work with the supplier who can provide you all the information you need to fully characterise and set up all of these values. |
| 10:49 | While some of your applications might be near stock, others might be more heavily modified and in a situation like that, before we really get rolling with the vehicle, you might actually want to make some changes to dial things back and make them a bit safer before you start the motor. |
| 11:05 | So for example, if we go to the spark advance section, under the high octane base spark table, which is our primary spark table that we're going to be using as long as the vehicle hasn't detected excessive knock and moved considerably towards the low octane tables, and let's just say we want to take a moderate load and select all cells across the entire RPM range from moderate to high load and let's just say we're going to dial these back a bit, let's say take 4° of timing out. |
| 11:45 | Now this doesn't guarantee that everything's going to be totally safe but let's just say your fuelling isn't quite spot on yet, at least you're not going to have lean fuel and lots of timing all combined, this will dial things back, make them a little bit safer as a starting point. |
| 12:01 | So after we've reduced the spark advance at moderate to high loads a little bit, let's go to the fuel section. |
| 12:09 | Under power enrichment, EQ ratio gas, this is where we find the EQ ratios that are going to be targeted during high load after power enrichment enable conditions have been met and delays have expired. |
| 12:23 | So in this case, let's see in the mid range, we see a bit of moderate enrichments at high RPM quite a bit more and when looking at these values, they might look unfamiliar if you haven't dealt with GM ECUs before so just a quick explanation of how power enrichment works. |
| 12:44 | These are EQ ratio values so you can think of this as the inverse of lambda and for example, just as an exercise, let's walk back one of these values. |
| 12:55 | So right here we have an EQ ratio of 1.16. |
| 13:00 | Let's open up our calculator. |
| 13:03 | And let's do the inverse of this value to get back to lambda so 1 divided by 1.16 gives us 0.862 lambda and then since we're working with pump fuel, let's use E0 stoich point of 14.7 for the calculation and we end up with an air/fuel target of 12.67 air to fuel on a gas scale. |
| 13:35 | And if that number is far more convenient and comfortable for you, that's a simple way to work it back. |
| 13:41 | If you're going to be doing a lot of this, I suggest setting up an excel spreadsheet to do it for you. |
| 13:48 | So as mentioned, I was thinking you know let's make things a little bit safer as a starting point, if you've got a really heavily modified vehicle. |
| 13:56 | So as an example, why don't we just bring in this full enrichment that they're using up top much sooner. |
| 14:04 | So we're going to do 1.19 not only at the top end as they had from the factory but all the way up off idle and that way again we'll be a bit rich, a bit safe, we'll have a little less timing and that gives you a better starting point. |
| 14:22 | Now for this particular application we're working with today, because we only have the aftermarket air intake and blower lid, we really don't need to be doing this. |
| 14:31 | So I'm going to back that change out and you'll notice that now the box is no longer highlighted as altered and we'll go back to spark. |
| 14:46 | And I'm going to add that 4° back in. |
| 14:54 | And now you can see again, no changes made since our last save. |
| 14:59 | So you wouldn't necessarily call these engine calibration changes so much as setup changes. |
| 15:07 | None of these are really going to provide a significant change in how the engine behaves in terms of start, partial throttle or even full throttle operation but we've set ourselves up at a good starting point to really get rolling on the tune itself. |
| 15:21 | So now we have our first modified tune prepared but before we flash that to the vehicle, we want to do some baseline runs. |
| 15:29 | This vehicle is close enough to stock, I believe it's going to be totally safe to do so, so in order to set up for those baseline runs, let's open up our VCM scanner software and let's set up to datalog. |
| 15:43 | This is also where we're going to monitor in real time while we're operating the vehicle. |
| 15:48 | So again we get the beta warning and we're going to go ahead and click through that. |
| 15:55 | Now as you'll see I have quite a lot of channels already populated here. |
| 15:59 | I also have a series of charts set up and graphs. |
| 16:03 | Now we've shared these with you in the form of a file that you can import into the VCM Scanner software. |
| 16:11 | To access this information in the channels section you're going to open a channel config and select our channels for 19 CTS-V. |
| 16:22 | Then in the graph section we're going to right click anywhere in this area, go to graphs layout and I'm going to demonstrate by deleting all of these here then opening our graphs file. |
| 16:41 | And you'll see that will populate all of these graphs. |
| 16:46 | Next in the charts area, we're going to right click again, go to charts layout and open our charts 19 CTS-V file. |
| 17:00 | So I'm going to skip over doing that as it would duplicate everything I've already loaded in from that file. |
| 17:08 | So this will save you a great deal of time, this list may not be perfect for your application. |
| 17:15 | For example you might have a turbocharged application and want to monitor wastegate duty or position on there. |
| 17:25 | You might have a situation where some of the items I'm recording are not pertinent to you. |
| 17:31 | I will say there are some extras on here. |
| 17:35 | Especially in terms of torque as I'd like to provide you with some additional feedback on where the torque values are coming from. |
| 17:46 | On the input side and on the output side, how do these things all come together and with a bit more monitored data, you get a bit better feel for where things are coming from and how they all interact and work together. |
| 18:00 | So as you'll see we have engine RPM, we have fuel rail pressure, we also have high side pressure from the direct injected system so this vehicle can actually monitor the low side pressure coming from the fuel pump in the tank forward to the DI pump and then it can monitor the high pressure system which feeds the DI injectors. |
| 18:24 | We have engine coolant temperature, manifold air temperature, not to be confused with intake air temperature. |
| 18:31 | So the intake air temperature will come from the mass airflow sensor, the manifold air temperature is integrated into the manifold air pressure sensor in the intake manifold. |
| 18:43 | We have some torque related values again, actual engine oil pressure, more torque values, more, more, more torque values. |
| 18:53 | Again we'll run through some of these, you certainly don't need all of them. |
| 18:58 | I've just provided this number of them again so that you get some additional data points and might want to dig in and see where everything's coming from. |
| 19:06 | In terms of mass airflow, we're going to have an airflow value as well as a sensor frequency. |
| 19:13 | We have our airflow generated from the volumetric efficiency function, the speed density portion of the system. |
| 19:23 | We have our air/fuel ratio commanded and EQ ratio commanded. |
| 19:28 | Short and long term fuel trims from both banks of the engine, again this is an 8 cylinder so we have multiple banks. |
| 19:37 | Ethanol percent, just in case someone else needs that, we will not be using E85 today, we're just working with pump gas, in our case a 93 octane fuel. |
| 19:50 | We have the fuel pressure requested and actual fuel pressure. |
| 19:54 | I have some injection timing related values. |
| 19:58 | Now if you're pushing the car on ethanol or you've massively increased the amount of airflow, you may need to keep an eye on your injection window and confirm that you're not exceeding it. |
| 20:10 | One way you can do that is by monitoring the car here. |
| 20:13 | Ideally you'll have a baseline of a stock or near stock vehicle to refer back to and that way you can better understand how far you've gone from stock and how much room you might have left to play with. |
| 20:29 | We have injector pulse width, both banks. |
| 20:32 | O2 sensor voltages, your engine load. |
| 20:37 | Throttle position, relative and absolute. |
| 20:44 | Throttle control source, so whether we're being limited by a torque control mechanism or otherwise. |
| 20:52 | This is that intake air temperature and then mass airflow sensor in our air intake system prior to the blower. |
| 21:01 | Manifold air pressure, cylinder air mass. |
| 21:04 | So we mentioned engine load here a moment ago, cylinder air mass is another measurement used for load and some other situations so it's important to have both. |
| 21:15 | Intake valve temp, then we have knock retard per cylinder. |
| 21:23 | This will come in handy, especially on this vehicle as in some situations a knock response is monitored while no knock is actually occurring and this will help narrow down whether the knock response is related to an actual knock event or not. |
| 21:43 | Next we see the air calculation mode and this will typically read normal or high speed. |
| 21:50 | So normal indicates that a hybrid mechanism of both speed density based on the virtual VE system, and mass airflow based airflow calculation is being used. |
| 22:03 | During transience, for steady state and they swap between the two, use a bit more of one or the other, then at higher RPM we switch into high speed mode which is going to be MAF only. |
| 22:16 | PE and COT advance, so this is related to the power enrichment, our cat over temperature protection and this is an amount of spark advance that gets added based on those conditions, can also be subtracted. |
| 22:31 | So in our case, we'll be keeping an eye on that and that will be core to how we tune this platform. |
| 22:37 | IAT advance relates to spark offset based on intake air temperature. |
| 22:42 | For example, if intake air temperature gets very high and there's an increased risk of detonation, you're going to see negative values there to reduce the spark advance and make things a bit more conservative to avoid detonation. |
| 22:56 | We have our base advance value which is going to come from our main spark tables. |
| 23:01 | Then we have our timing advance which is the actual amount of timing that the engine is running. |
| 23:08 | So there are many factors that feed into this value, this is the final out the door value as I like to call it, the one that the engine is actually operating at. |
| 23:19 | Next we have knock retard which is the typical one we're going to be watching out for for real knock behaviour. |
| 23:26 | But as I mentioned, these computers can do something sneaky that makes it look like knock is occurring when it isn't really, so we'll keep an eye on that. |
| 23:34 | Then we have total knock retard which incorporates knock retard as well as other functions such as the burst response and other safety measures. |
| 23:44 | A knock learning factor, the spark state, which mentions where the spark advance source is coming from. |
| 23:55 | So most of the time this is going to be based on toque control and as long as we're operating within our torque limits, this isn't going to hinder us at all. |
| 24:04 | The amount of power enrichment, whether closed loop fuelling is active or not. |
| 24:10 | Catalyst temps for both banks. |
| 24:13 | Now this is really important because this will let us have a pretty good picture of whether we've entered a cat protection mode or not, so we'll keep an eye on those. |
| 24:22 | Then we have our intake cam angle desired and actual. |
| 24:29 | Trans output shaft RPM, trans current gear and vehicle speed. |
| 24:34 | Again, some of these values are going to be more useful to you than others, depending on your application but we've given you a pretty good list to start from and you can add or subtract as needed from there. |
| 24:44 | In terms of the charts in the graphs section, those will be easier to look at and you'll better understand why we've set them up as we have once we get some data to look at. |
