Practical Reflash Tuning: Step 6: Confirm Calibration on the Road
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Step 6: Confirm Calibration on the Road
14.35
| 00:00 | - We're now at the last step of our reflashing process and this is the opportunity to take the car off the Dyno and confirm that everything we saw on the Dyno matches up with what we're seeing out on the road or on the race track. |
| 00:13 | We want to make sure that our real world conditions match what we had on the Dyno. |
| 00:18 | Now we're really looking at three separate areas while we're doing this. |
| 00:22 | First of all, what we want to look at is that under cruise conditions, our short term and long term fuel trims are still very close to zero. |
| 00:30 | So we want to drive the care here in the same way that we normally would out on the open road. |
| 00:35 | We're looking for smooth, consistent throttle application and the same rpm range and load range that we would actually be using to cruise the car on the road. |
| 00:46 | The next area we're looking at is our wide open throttle operation, and we're looking here to make sure that our air fuel ratio matches what we saw on the Dyno and of course we're looking to make sure we're not seeing any knock events that we weren't seeing on the Dyno. |
| 01:01 | The last part is to confirm that our transient response is good. |
| 01:04 | We're looking to make sure that the car feels smooth on throttle application and again we're making sure that we're not getting any transient knock events. |
| 01:13 | Right, well let's start the car up and we'll go for a drive. |
| 01:18 | When we're logging this sort of data, we want to make sure that the car isn't heat soaked and this can be a problem particularly with reflashing where we're spending a lot of time with the engine shut off, the engine's hot, while we're actually performing a reflash. |
| 01:33 | So particularly after we first restart the car, we want to allow the engine some time, a minute or so of driving just to reach normal operating temperatures then we can start our logging. |
| 01:44 | So first of all, what I'm going to be doing is just simply driving the car at a relatively normal open road speed, so I'm sitting at the moment at around about 90kph, we're in 6th gear at about 2200rpm. |
| 01:57 | What I want to do is just smoothly move the throttle so we're not applying any transient corrections to our fueling. |
| 02:05 | And at the moment we don't really need to be viewing the laptop, this is the great thing about the data logger, we can just simply drive the car. |
| 02:13 | I am occasionally glancing at my wide band metre which is stuck to the windscreen. |
| 02:17 | So I'm still able to concentrate solely on driving the car and keeping control of the car. |
| 02:23 | So after we've gathered a little bit of data with our data logger, what we can do is shut off the car, pull over to the side of the road or into the pits if we're on a race track, and simply have a look at the data that we've logged. |
| 02:36 | So let's do that now and we'll see what our closed loop fuel trims look like. |
| 02:41 | Okay, if I open our log file that we've just made here and we'll go through to our time graphs and what I'm going to do first of all is uncheck all of the time graphs so I'm only going to be looking at a few key aspects. |
| 02:54 | We're going to be looking at our engine load and our engine rpm. |
| 02:57 | I've added accelerator angle so we can see what I was doing with the throttle. |
| 03:01 | We're looking at commanded air fuel ratio, we're also looking at our fuel system status and then, obviously our fuel short term and long term trims. |
| 03:11 | I'm also going to add in our LM2 wide band, so we can just see what our actual wide band was, and during our closed loop areas we can actually use the on board air fuel ratio sensor as well. |
| 03:24 | So let's have a look at what we had here, our air fuel ratio from our on board sensor is constantly sitting at around about 14.6:1 which is great. |
| 03:33 | We come through to our commanded air fuel ratio and you can see that, as we'd expect, is sitting in our closed loop area of 14.5 in this particular instance. |
| 03:44 | We can check our fuel system status and we can see that that's staying in closed loop, which is indicated by the number two, so we know we are in a closed loop. |
| 03:53 | Let's have a look at our fuel trims because these are the area that we are most interested in. |
| 03:58 | And you can see that, for the most part, our trims are matching what we had on the Dyno. |
| 04:04 | We've got a total trim here of a bit over 2%, and you can see as I move through the log file that that's staying relatively consistent. |
| 04:14 | Now we can see this is why I was saying that we need to make sure that we're consistent with our throttle application. |
| 04:19 | We need to understand what we're looking for in our log file. |
| 04:23 | You can see here that I shifted gear, so I've closed the throttle and reopened it. |
| 04:28 | At the same time we've seen the engine load drop down and we've seen our commanded air fuel ratio change dramatically. |
| 04:35 | Our fuel system status is momentarily gone into open loop and you can see that this has affected our fuel trims momentarily in this area. |
| 04:44 | So we want to completely ignore any data where we've changed gear or where we've got a large change in throttle opening. |
| 04:51 | So this is the sort of data we want to look at. |
| 04:53 | In general, we would make a larger log file looking at a broader range of rpm and engine load but essentially we're doing the same thing, we're analysing that data looking at how closely our short term and long term fuel trims are matching up and that's going to indicate if we need to make any further changes to our MAF scaling. |
| 05:12 | Alright let's go for another drive now and we're going to look at some wide open throttle power runs. |
| 05:17 | When we're looking at doing some wide open throttle power runs, we need to be able to apply a reasonable amount of load, so there's no point doing these power runs in first or second gear. |
| 05:27 | We really need to look at third or fourth gear or perhaps if we've got the ability on a race track we need to do a full power acceleration run through third, fourth and perhaps fifth gear and it's going to give us a good range of data. |
| 05:42 | Again, we don't want to do these runs straight after the engine has been restarted because it may be heat soaked. |
| 05:48 | So again, we want to make sure that we get our engine to a normal operating temperature before performing our full throttle power test. |
| 05:56 | I'm going to perform my full power test in third gear and I'm going to start at about 2000rpm and I'm going to run all the way through to the engine rev limit. |
| 06:04 | What I want to do is capture the full engine rev range so I've got a good amount of data to look through. |
| 06:10 | Now while I'm doing this, we're going to be logging the data to a file, so we don't need to be watching the laptop, we can concentrate on the road. |
| 06:18 | We've got our wide band metre sitting on the windscreen so we can glance at that occasionally and just make sure that our air fuel ratio is at approximately where we need it to be, and then after we've done that run we can stop, pull over to the side of the road and we can have a look at that data. |
| 06:35 | So let's do that now. |
| 06:49 | Alright so we've got our log file now, all we need to do is pull over to the side of the road and we'll go and have a look through that log file and see exactly what we had. |
| 06:57 | Okay, so we've got our log file open now and I've zoomed in on the area of interest. |
| 07:01 | What I'm looking for here is our accelerator angle and this just indicates the area where we were at wide open throttle. |
| 07:08 | The next thing I'm going to have a quick glance at is our advance multiplier. |
| 07:12 | Simply what I want to do is make sure that that was sitting at 1.0 the entire way through the log file, which you can see that's exactly where it was, so that's great. |
| 07:21 | So we can get rid of a couple of parameters here just to make everything a little bit easier to view. |
| 07:27 | We don't need to worry about our coolant temperature. |
| 07:29 | I'm going to leave our engine load and our engine speed visible and that's simply so that if we need to make any changes to our file, our rom, we can figure out exactly where we need to make these changes. |
| 07:43 | Next we have our commanded air fuel ratio and we can see that that's sitting at around about our target from our open loop table so that's what we're going to be referencing our measured air fuel ratio against. |
| 07:57 | I'm going to get rid of a few more parameters relating to our fuel system. |
| 08:02 | We've got our short term and long term fuel trims shown now and all I'm really looking at here is to make sure these are both sitting at zero when we are in a open loop and they were. |
| 08:12 | Now we've got our ignition factors, this is what we are going to be using, so this is what we are going to be looking at. |
| 08:18 | First of all, in order to decide if the engine was suffering any knock during this file. |
| 08:24 | The first thing I'm looking at is our ignition correction fine and remember, we want our ignition correction fine to be sitting at zero anywhere through this log file and you can see it particularly, at least under wide open throttle here during this particular log, we are sitting at zero so this means no knock is occurring, the ECU isn't pulling any ignition timing and response to a knock event. |
| 08:49 | So this means that our ignition timing is sound, we don't need to make any changes to our ignition map. |
| 08:55 | Last thing we're going to have a look at now is our air fuel ratio. |
| 09:01 | So we have the information from our LM2 wide band sensor and what we want to do is simply have a look at what that was doing during our wide open throttle period of operation. |
| 09:13 | So the value's being displayed here and you can see that, remember our target is 11.8, and we are sitting a little bit leaner than that, we're sitting more likely around about 12.0. |
| 09:26 | Right on the top end, we do see that our air fuel ratio does in fact dip down towards our target. |
| 09:33 | So in this instance what we can now do is go through and make any changes to our air fuel ratio target map based on this data. |
| 09:42 | Now, again, as long as the change that I need to make is minor, in the region of 1 or 2%, I'm going to generally make these changes to our AFR target map. |
| 09:53 | If, on the other hand, we're seeing more dramatic errors and we shouldn't because we've dialled in our MAF scaling correctly and we've tuned the engine correctly on the Dyno so we shouldn't see massive changes but if for some reason we're seeing a need to trim our fueling more than about 1 or 2%, in that case we would look at making our changes in our MAF scaling instead and that's why we're logging at the bottom here, our MAF scaling, both our mass air flow in grammes per second as well as our mass air flow in volts. |
| 10:27 | So we can base our decisions on where abouts in the log file we were lean and then make changes to the corresponding area of our MAF scaling. |
| 10:39 | Now I'm not going to go through the process of that it's just a repeat of what we saw on the Dyno. |
| 10:45 | So by this point essentially our tune is complete. |
| 10:47 | We know that we've got good control over our fueling and closed loop with minimal trims and we know that our air fuel ratio is matching our target under wide open throttle conditions and we also know we've got no knock occurring under those wide open throttle conditions as well. |
| 11:02 | The last part of our task I always like to check the transient response of the engine. |
| 11:07 | What I mean by this is the way the engine responds to sharp throttle inputs. |
| 11:11 | What we're trying to do here is get crisp response to our throttle input and match, essentially, the way the factory engine responds. |
| 11:19 | The need to make large changes to our transient enrichment is normally something that is going to come with upgrading our fuel injectors to a larger injector, for example. |
| 11:29 | So in this particular application, despite the fact we have fitted a supercharger, I'm not expecting to need to make massive changes to our transient enrichment and I already know that the engine does feel crisp and responsive. |
| 11:42 | So the way we want to do this is to drive the car and simply make sharp throttle inputs and this is about as much coming from the feel, how the engine responds from the seat of the pants as it is from data logging we want a crisp, sharp response to that throttle input with no hesitation, no bogging, no lag. |
| 12:01 | So let's go for a drive and see what we've got. |
| 12:04 | Now when I'm performing these sort of tests I want to do them in two separate ways. |
| 12:08 | One of the ways I'm going to do that is from low rpm so in this case I'm at around about 2200rpm and I'm in third gear and I'm just going straight to full throttle. |
| 12:18 | So what I'm looking for is smooth operation with no bogging, no hesitation, and that's exactly what I've got. |
| 12:25 | So this would replicate the sort of situation where we are mashing the throttle wide open from low rpm and trying to accelerate quickly. |
| 12:34 | The other way I'm going to do this is from a higher rpm say around about 4000 rpm and I'm going to get the engine up to 4000rpm at steady speed and then just go straight to full throttle. |
| 12:46 | And again I'm looking for a really crisp and sharp response to that throttle input, no lag, no bogging and I'm looking for my air fuel ratio to quickly track towards my target. |
| 12:57 | The other thing we're looking for when we are testing our transient response is to make sure that we're not getting any knock retard when we are mashing the throttle wide open. |
| 13:06 | It isn't uncommon occasionally to see our knock correction pull one or perhaps two degrees of timing and response to this. |
| 13:15 | Now remember that knock correction is used as a feedback for instantaneous knock events that the ECU doesn't deem to be repeatable. |
| 13:25 | So that's not necessarily a problem, what I'm looking for is if I see the occasional knock retard event like that, I'm not going to be too concerned about it. |
| 13:34 | If we are repeatedly getting knock events on a sharp throttle input, in that case we would want to go and revisit our ignition timing map and remove some timing from those areas we're operating in during our transient. |
| 13:48 | Alright so this brings us to the end of our Ecutek worked example. |
| 13:52 | We've now got a complete tune for our supercharged engine, we're happy with the power it's making, we're happy that we've got good control over our air fuel ratio and the engine isn't knocking. |
| 14:03 | More importantly with our knock control, because we're not relying on our knock control constantly to be pulling timing in order to keep the engine safe, this does mean that if the driver ends up with a tank of lower octane fuel for any reason, we still have the full range of that safety function with our knock control in order to remove timing and keep the engine safe. |
| 14:28 | Alright thanks for joining us and I hope you've enjoyed this worked example. |
