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Practical Reflash Tuning: Step 4: MAF/Injector Scaling

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Step 4: MAF/Injector Scaling


00:00 - Now we are ready to connect to the vehicle.
00:03 So we're going to turn the ignition on.
00:07 Again depending on whether you have a key start or push start vehicle, that process will be a little different.
00:13 Just ensure that the vehicle is fully powered up to ensure that you'll be able to actually communicate with it.
00:20 We're going to click this button here which will connect to the vehicle.
00:23 It's going to gather a series of information which lets the VCM Scanner know what PIDs or monitors are actually available.
00:32 If you have any on your list which are not associated with this vehicle, they will not be displayed at this point, they will be hidden.
00:41 Alright so, looks like we still have quite a few channels so our channel list aligns with this vehicle.
00:52 And even though we haven't started the vehicle yet, let's just click this record button to start scanning.
00:59 And we'll see that we start getting data.
01:02 So values here in the chart are populated, values here in the channels screen are being updated and now we're ready to go, let's go ahead and start the engine.
01:20 Alright so now that we've got the engine running, as you can see, a lot more values are moving around.
01:28 Engine RPM is settling in.
01:32 Let's take a look at our fuel trims, so those are set up here in this row on the chart.
01:40 We see we have a short term trim, occurring, this is pretty common in a cold start situation.
01:48 I'm not seeing values that are outside of a reasonable range so let's just see where those settle in.
01:57 If you're seeing values of let's say -25 or +25, you're pretty far outside the normal range and at that point, if the engine is also stumbling or extremely rich, I would suggest stopping at that point, double checking the vehicle mechanically, perhaps measuring the MAF housing on your intake, confirming it really is similar to stock and if you need to make a base adjustment to your MAF scaling at that point, I would go ahead and do so there.
02:34 Again perhaps you've forgotten to make a displacement adjustment in that setting as well or perhaps an injector setting isn't quite right but in our situation we know that we have stock engine, stock injectors, stock sensors so we should be pretty good as long as our mass airflow intake system is working well and it looks like as the engine is starting to warm up a little bit, these values are already coming down, getting a bit closer to 0 so well within tolerance and we're just going to let the engine continue to warm up.
03:08 Once the engine's fully warm, then we'll see where things really stabilise.
03:12 During warmup enrichment, it is common to see fuel trims that are a bit larger or further from 0 than usual and we won't worry about that too much, as well as we're well within the control range of the ECU.
03:26 What we don't want to see are values that are so large that the ECU cannot get the engine on its air/fuel target.
03:33 So while the engine's warming up, you might have noticed air/fuel commands updating, you'll probably notice that now we've built in some long term fuel trims which are offsetting those short term fuel trims we started out with.
03:48 And can see that our fuel pressure seems pretty stable, on the low side, high side pressure, in the 300s which may seem like a lot if you haven't worked with a DI system before but actually quite low for this system's potential and as we really get into more heavy load you'll see that these values will go up in the ballpark of 3000 psi.
04:15 In terms of engine torque, looks like we're making about 10 to 20 foot pounds of torque in order to keep the engine turning over at idle, well under the max torque and peak torque allowed by the system.
04:29 Again as we mentioned earlier, good to keep about a 100 pound foot buffer between the engine torque measured and the peak torque value.
04:39 We're certainly well under that at the moment so no issues there.
04:44 And then right now we can see that we aren't really requesting any torque from the pedal.
04:49 I know this may be hard to see but this is my driver pedal torque request.
04:57 So right now not requesting any.
05:00 I'll give the throttle pedal a little blip just so you can see that.
05:04 So there's a quick blip there and you can see that jumped up as well as the immediate axle torque and the actual axle torque.
05:14 Other than that, can see our main knock retard and total knock retard values which we'll get into more as we're operating the vehicle under load.
05:26 Our throttle position, so we're about 6.3% open, dipping down some of the time to provide enough airflow for idle.
05:36 We have our base advance which comes from our table values.
05:40 And then our spark monitor, is going to show the final timing that the engine is actually running.
05:46 Currently our wideband is reading a very high value because we're sniffing at the tail pipe.
05:51 We really don't have a need to get accurate readings at low airflow like at idle since the factory sensors are doing that for us and providing us this fuel trim feedback which we can make MAF scaling adjustments from as well as virtual VE adjustments if necessary.
06:10 Our intake air temp is about 59, manifold air temp, about 100°F, coolant temperature still warming up, only at 145.
06:22 One we get into doing some power pulls, I want to keep an eye on the manifold air temperature value, this is a water to air cooled supercharged system, as that water heats up, as the manifold heats up, we can see this number get rather high so I want to make sure we provide ample time for cooling between pulls, also whenever possible, ideally you want to start each power pull with values that are relatively consistent.
06:51 So that way you'll be able to see whether a change is induced by a change in the starting temperature being significantly hotter or colder, or based on a change that you've actually made in your calibration.
07:04 So we pretty much know that on a cold day like today, we're going to see some great numbers on our first pull but after we get some heat into the engine bay, warm things up a bit, I think we'll start to see numbers stabilising and then from that point we'll be at a good spot to start making changes and see if we get a net gain or loss.
07:25 So each time you start the engine up, there's a few things that you want to make sure are operational before you really get into driving or doing power pulls.
07:34 One of those is going to be the O2 sensors and fuel trimming.
07:39 So when you start to see these values here like the short term bank one and bank two moving around, as well as the voltage readings, you know that those systems are up and operational.
07:50 So the engine isn't quite up to full operating temperature yet but in the meantime, the other thing we can keep an eye out for is our intake cam phasing system.
08:01 And in this case, while we're monitoring intake cam angle and desired angle, we're really talking about manipulating the only cam the engine has which is for intake and exhaust.
08:11 So let's bring the engine RPM up and I'm doing so in park and we can see that as the RPM increases, that system activates, we are on our target, system is functioning properly.
08:27 So not only is this system awake, it's phasing to the target, no issues there.
08:33 At this point we're pretty much up to operating temperature, little bit on the low side at 172°F.
08:40 I'm going to get the car into gear and let's just start rolling it, I'm going to put it into manual mode, paddle down, make sure we're in manual mode.
08:53 And just get the vehicle rolling gently.
09:00 As soon as you start driving, keep an eye on the fuel trims, just make sure those don't start to go out of bounds.
09:10 You may be in a situation where at idle the fuel trims were acceptable but once you're driving they might not be.
09:18 And when I say acceptable, generally what I'm talking about is about +/- 10%.
09:24 We are within that range currently.
09:28 In fact we have long term fuel trims which are around -8 and then short term fuel trims which are dancing between slightly negative and slightly positive so things have settled in pretty well in this area.
09:47 We're not seeing any knock response, vehicle continues to warm up at a reasonable rate.
09:57 We see our O2 sensor's voltages bouncing back up and down, gives us a good indication that the catalysts are operating correctly.
10:19 Alright let's let the vehicle fall back down to idle.
10:26 So at this point we've got the engine coolant temperature up to 185.
10:31 Let's check on our oil pressure, oil pressure's 30, manifold air temperature 122.
10:39 Intake temp, realistically going to stay pretty cold today, it is chilly.
10:45 Now that the vehicle's up to operating temperature, we see that our fuel trims have settled in, they're looking pretty reasonable, we have bank 1 at a -9 long term trim but a positive short term trim so we're actually ending up somewhere around 7 or 8%, well within our +/- 10% range I'd like to keep us within.
11:09 On bank 2, things are a little bit tighter to 0, we're at -4.7 and a positive 1-3 let's say so our total trim on that side is actually only a couple of percent.
11:20 Over here, in our long term plus short term fuel trim table, we're displaying the average values function and this is taking the average of both banks, long and short term trims, putting it all together, giving us a decent picture of where we are.
11:40 So right now we're seeing about -5, -6, looking pretty good already.
11:45 We can certainly improve upon that with some MAF scaling but this is great for now and let's get the car rolling and see what it does when it's moving, that way we can make a broader change all at once and reduce the time spent making flashes.
12:03 So get the car in drive, I'm going to put it in manual mode, paddle it down and bring it up to speed.
12:14 Now when you're just starting out with the tune, I definitely recommend taking it easy, light on the throttle, if anything feels jerky, it's usually a good indication that your fuelling is a bit further off than you'd like.
12:29 The other indication of course is the fuel trims so because we're at light throttle, we're operating in closed loop fuel operation.
12:37 Fuel trims are active and they're giving us a pretty good picture of where we are.
12:41 Right now, again -10, -8 long term, could be a bit better but with these small short term trims, we've got the car on target and that's what we want to see.
12:55 So our air/fuel commanded is actually looking a bit different than our air/fuel on our wideband and that's because the air/fuel command is based on E10 fuel so 14.1 is actually lambda 1 on E10 fuel and if we go to our equivalence ratio commanded monitor in our channel section you find lambda 1 is being commanded so there we can confirm that.
13:29 Let's give it just a little bit more RPM, see if things stay relatively close to 0 in terms of fuel trims, I'm also keeping an eye on the knock monitors.
13:44 While it's unlikely you'll see significant knock in a light throttle situation on a vehicle that isn't heavily modified, always good to double check.
13:54 Alright so we've gone up to about 4000 RPM, going to slow back down.
14:03 So this is giving me a bit of a snapshot of what we're starting from and as you can see we're starting to populate our table here, our graph.
14:14 As we fill in more data there, we'll get a clearer picture of the adjustments we're going to want to make to our MAF scaling so what I'm going to do now, that I verified things are reasonably safe, is I'm going to try to fill in more of this graph so that we have more data to work from when we make our changes.
14:37 So I'm manipulating the throttle in order to let the vehicle slow down, fill in some of these cells down here.
14:48 And then I'll gradually work my way up by applying additional accelerator pedal position.
14:55 And this is going to be increasing airflow which will bring us downwards on this X axis.
15:02 As the vehicle accelerates we're also going to head to the right as the engine speed increases.
15:10 And I've set up a filtering mechanism so that multiple samples are required before this all gets populated.
15:18 That way you don't end up with super errant transient data which might negatively impact the quality of your MAF scaling changes that you make.
15:29 So we'll gradually walk our way through this table.
15:42 And it looks like in this area here, we have a more significant amount of air than other areas.
15:51 And now we've got up to about 4000 RPM so what I'm going to do is I'm going to slow down and next time I'm going to grab one gear higher and that's going to allow me to apply more load at a lower RPM without revving the car out and without applying a whole lot of load, just giving us a bit more airflow.
16:27 Alright let's do that again.
16:30 So I'm going to go up a gear, bring our RPM back down and then this time I'm going to apply some accelerator pedal a little bit quicker.
16:39 That way I get up to a higher airflow without the engine revving out too high, too quickly.
16:44 So here we go.
16:55 Again watching fuel trims, watching out for knock, everything looks good and we'll back it down.
17:07 So we haven't run into any real knock here, our fuel trims are still looking totally reasonable, however it looks like there's plenty of room for improvement.
17:19 At this point because it's a negative fuel trim, we know that the engine is inherently running a bit rich and then correcting up to target.
17:27 This is a bit safer than being lean and then adding fuel to get back down to where we want to be.
17:34 Because I know it's either on target or a bit rich until trimming occurs, I'm going to push it just a bit further, again so we get more data before we make our first change.
17:45 What I don't want to do is assume that based on the areas we have walked our way through, I know exactly what's going to happen at higher airflows.
17:54 So let's get up to a higher airflow and see what happens.
18:10 Alright so in that scenario, I was moving through different RPM ranges more quickly because I applied more throttle, the engine as making more power, it was revving out quicker than we could accumulate valid data to populate in our table.
18:27 And that's fine too, so instead of looking in the table at that point, you can just be looking at the raw fuel trims here, making sure things seem safe, watching the knock retard and everything looks good there so that's about as far as I want to take it at this point.
18:45 So we'll get the car stopped, we'll get it into park, I'm going to stop our datalog.
18:54 And now let's just look through the graph data that we've recorded so far.
18:59 So we have some negative values here, we have a few stray positive values in this area which is interesting.
19:09 Usually MAF scaling will be relatively linear but sometimes on a particular aftermarket intake you'll end up with an area where it has a non linear response and sometimes you need to account for that.
19:25 Other than that it looks like we're mostly dealing with negative values so these negative values seem to range from most of them about -5 to -10, in some areas a bit more, a bit less than that.
19:43 So realistically we could get down, we could get nitty gritty and we can make different changes in different areas but if we're just looking to take a first shot at this, it looks like we could probably take let's say 4% out of our MAF scaling across the board and likely be in good shape.
20:04 What I would advise avoiding is making changes at very high airflow until you're absolutely certain of what's going to happen though.
20:14 At this point we're not ready to actually make those changes, I really just wanted to get a feel for whether the engine's operating safely or not before we attempt some baseline full throttle pulls.
20:24 So while we're not ready to make changes, we recorded some valuable data here.
20:29 I want to save this before we lose it so let's go over here and we're going to save this log file and we're going to call this baseline stock partial throttle 1.
20:52 Now we're going to start a new datalog while we record our first baseline pull.
20:57 I've set up our chassis dyno with the vehicle information and now I'm going to set it up for a power pull.
21:09 When setting up a power pull on the dyno, often times you'll need to set boundary conditions such as the start and stop engine speed for the dyno pull.
21:19 In this case, if we haven't tuned this engine before, how do we know where to stop.
21:23 Let's start by taking a look where the factory rev limiter comes in.
21:28 We'll go back to our VCM Editor software.
21:33 To the engine section.
21:37 Fuel.
21:39 And to the cut off section.
21:41 Now here we have extreme cutoff.
21:50 In gear which comes in at 6600.
21:57 Temperature base cutoff.
22:00 And this indicates that at any, certainly any reasonable engine temperature, 6600.
22:09 So at that point we can pretty much say, 6600 is where the engine's probably going to cut off so let's stop our pull just short of that, for now I've set it up for 6400 RPM.
22:24 Back to our scanning software we go.
22:27 Now during this pull we're going to be looking for some similar things, some different.
22:31 So similarly we'll be looking at knock retard and total knock retard.
22:37 We also are going to be looking at wideband this time and the reason that wideband is so critical now is as we floor the vehicle we're going to end up in a condition of open loop fuelling.
22:50 So open loop fuelling meaning no fuel trimming will occur.
22:54 The fuel trim monitors will no longer indicate how close or far we are from our air/fuel target, we'll need to rely on the wideband for that.
23:03 So let's get this pull started.
23:07 On this vehicle we're going to be using 4th gear, while that is not the 1:1 gear, it's a gear that results in a reasonable length of time for a power pull to take.
23:23 5th gear would be a bit closer to appropriate but also very long and punishing on the vechicle.
23:31 So it's important to pick a gear that's going to provide a long enough pull to significantly load the vehicle but not too long to be abusive so use your best judgement.
23:47 In terms of gear, I'm going to confirm the current gear here.
23:55 We're up into 4th.
23:57 If you're working with an automatic, it's important to confirm that the vehicle stays in the intended gear for every pull.
24:04 In some situations, if you let the RPM fall low enough, the vehicle may downshift on its own, even when in manual mode, so keep an eye out.
24:14 So we'll slowly let our RPMs drop, I'm going to try to start this pull around 1500 or 1600 RPM.
24:25 Alright.
24:27 And just to show you, if I let it dip too low, you can see our trans current gear has dropped down to third.
24:34 So bring the engine speed up just a little bit so it'll allow me to shift up to 4th, grab 4th.
24:43 Now slow back down but not low enough that it kicks down into 3rd gear.
24:50 And on this vehicle that seems to be right around 1500 or 1600 so that's how I've selected where we're going to start our pulls.
24:59 I'll start the dyno recording.
25:11 And let's give it a pull.
25:12 Again watching our knock retard and our wideband for safe values.
25:18 For a supercharged system like this, I'd like to see values well under 13 and in terms of knock, we'll just have to see what we get but because this is a relatively factory setup, we can be confident that what we're going to see is likely indicative of how the vehicle would perform if totally stock.
26:01 So I've stopped our log, going to drag this back so I can see the pull.
26:08 There are a few ways you can quickly find the pull, one of which is the strip chart down at the bottom and this indicates engine speed, so where you'll see it ramp up aggressively to a high peak, gives you a pretty good idea that's where you perform your power pull.
26:25 Also here in the bottom we have our torque, axle torque values and you'll see those spike up massively during a pull so that makes it pretty easy to find.
26:35 Now let's start to pick apart what happened during this pull.
26:39 So at the end of a first pull especially, but really after the end of any pull, I like to see if there's been any knock behaviour.
26:46 So if we look at the start of the pull, and again we're looking at these numeric values here, we're seeing 0, so no rock response before the pull, I'm going to scan through here by clicking and holding my cursor and dragging it over.
27:02 We see as the green line for throttle ramps up, we start to get some knock response and it's showing up on both monitors, the knock retard and the total knock retard.
27:14 And it looks like that ramps up to a peak here, and we're getting about 2.5° of knock retard, 4.9° total knock retard.
27:27 While that might sound like a lot, and on an older vehicle, perhaps a GM Gen III, that would have been a bit concerning, there's something going on that's a bit different on these Gen V engines.
27:39 So over here, if we look at knock retard per cylinder, you'll find that we're actually not retarding the timing at all on any cylinder based on a knock event.
27:52 So what's happening here is, we're monitoring knock retard, but knock retard is not actually occurring.
27:59 Now let's look at this again in another way, just so we can prove that out for you and give you a bit more confidence that that's actually what's happening.
28:07 So down here, we're monitoring a few different things, which help us arrive at our final spark advance value.
28:14 We have 2.5° of timing added to the timing advance based on power enrichment and catalyst over temperature.
28:22 So we're not in a catalyst over temperature situation here but we are in power enrichment mode.
28:27 And because the vehicle is being enriched, we are allowing more timing advance to be applied.
28:34 So we add 2,5° there, then we take 1.5° back out due to the current intake air temperature.
28:43 And another -2/10ths here based on the current coolant temperature.
28:47 So if we add these values together, 2.5-1.5, we get 1-2/10ths, we get +0.8 as our net effect.
28:57 Then we go over here to our base advance which is our timing coming from our main timing tables.
29:04 We add 0.8 to 14.4 and we do get a bit over 15.0 that we've monitored but certainly not enough that we're seeing 4.9 or 2.5° taken out of our spark timing.
29:19 Now there is a small discrepancy here, likely based on other adders which we aren't currently able to monitor but what we can see here is these knock retard values are not being applied.
29:31 And again we've confirmed it by looking at our individual cylinder knock retard as well as going through the math from the base timing, adding the advance corrections on and then seeing what our final out the door spark advance is to confirm.
29:46 We are actually getting what we expect as if no knock is occurring and I think at this point you're starting to get the picture that this is just how it's going to be and we're going to have to, I won't say ignore that, but treat this as baseline normal for these vehicles.
30:06 Now I've dynoed multiple GM Gen V vehicles in stock form and this behaviour has been consistent across them so what I do suggest is keeping stock of what RPM you see each value for knock retard and total knock retard, kind of keeping in your head what's normal and then if you see a situation where those values increase from their baseline value, or you see knock retard actually occurring on a per cylinder basis, now you've actually got some knock that you want to be concerned about.
30:45 Then at higher RPM after about 5200 on this particular vehicle, we're seeing no knock behaviour at all.
30:54 So in that area, if we make changes and we start to see some knock retard there, we have actually induced knock and we probably want to make some changes to mitigate that.
31:04 Another thing of note is that when we go into a power enrichment and a high load situation, with lots of airflow, significant exhaust heat and pressure, we come out of closed loop fuel operation and into open loop.
31:17 So if we look here, before the pull, fuel trims were non zero, then the pull starts and we see these short term trims both go all the way to zero.
31:32 However, long term fuel trims may remain and it's important to make sure, as you go through the MAF calibration process that you hit areas not just at light load but also moderate loads which lead into open loop operation.
31:48 That way, those long term trims will be minimal and you won't have a significant long term trim applied during full throttle open loop operation.
31:58 Other than that, let's take a quick look at our temperatures.
32:01 So we started the pull with an intake air temperature of 91, manifold air temperature of 155, engine coolant temperature of 207.
32:11 If we scroll through, as we're going through the pull, we see intake air temperature actually drop.
32:25 Manifold air temperature remaining relatively constant.
32:30 Engine coolant temperature also remaining pretty constant.
32:36 Which is great, so it looks like we're not getting the engine coolant temperature excessively hot during pulls, we're seeing relatively stable manifold air temperatures which means the water to air system is doing its job quite well and the intake air temperature again has gone from low 90s to about 75, now how has that occurred? So typically what we see happen during a dyno pull is the engine's just been sitting idling, it's a bit heat soaked.
33:05 When you start to flow a whole bunch of air through it, the cold air being drawn into the air intake will cause that drop in intake air temperature.
33:13 Next I'm going to take at our air/fuel ratio on our wideband during the full throttle run and see where we are.
33:20 Now based on our minor exploration of the MAF scaling and our fuel trims, I have a hunch that we're going to be a bit rich of target because all of our fuel trims were negative, indicating less airflow was actually present than what was expected with the factory MAF scaling.
33:37 So let's take a look, at the start of the run.
33:45 As I'm looking at this white line here, this is our wideband air/fuel, we can see where it starts to dip down and then if we look over here, right where it starts to dip down, that's where power enrichment comes on.
33:59 So if I go back a little bit, can see it's off, then it comes on.
34:05 As power enrichment comes on, it doesn't apply all of the enrichment immediately.
34:11 So we're going to see this gradually ramp in.
34:18 Looks like a nice smooth transition and at this point, safe to say that we've fully transitioned into power enrichment mode, we're seeing air/fuel ratios monitored on the wideband in the low 11s, where we have a commanded air/fuel of 11.76.
34:39 On the top end of the range, looks like we've gone into the 10s.
34:45 So quite a bit away from our air/fuel command.
34:52 Now as we talked about earlier, when we were looking at our long and short term trims, I was saying, we could probably pull about 4% out of our MAF scaling now and be OK.
35:01 It looks like, based on the air we're seeing from command at this point, that taking the 4% out of the entire range is going to be just fine and certainly get us closer to a desired effect at full throttle.
35:18 We would really like to see the wideband air/fuel monitor be a bit closer to the command.
35:24 So let's go ahead and head back over to our VCM editor software and start making those changes to our airflow vs frequency table under the MAF calibration section.
35:37 As you can see when I've opened up my MAF scaling table, I have both a numeric set of data and a graphical representation.
35:44 I find this very useful, particularly for MAF scaling to ensure that as I make adjustments, I maintain a nice smooth curve.
35:52 What we want to avoid here is any abrupt changes that might cause undeesirable drivability effects.
35:59 So to get to this view, you're likely, on the no split default, if you want to see numeric data only, this is what you would do.
36:10 If you'd prefer graph only, you can click this button.
36:14 If however you'd like to go with the representation that I've chosen, you can do a horizontal split which will give you the numeric data up top and the graphical representation on the bottom.
36:24 I find it's easiest to make my actual data changes in the numeric section and then visualise them on the graph section.
36:33 Because we've decided to make a change in all cells, I'm going to control A to select all and then I'm going to remove the 4% we talked about by multiplying by 0.96.
36:47 So there isn't a percent change function, so what we do instead is we apply a multiplier, has the same effect.
36:55 Subtract 4%, take it out of 1.0, subtract 0.04 which would be the decimal representation of 4%.
37:04 And we can 0.96 so we enter that, press multiply, we've made our change, I can see from the graphical representation I haven't altered the shape of the curve, I've merely shifted it downward and that's the desired effect we're looking for at this time.
37:21 That'll get us more in the ballpark and then we can make more nitty gritty changes as we go.
37:26 Now that we've done that, before we've forgotten what's just happened on our power pull, let's take a look at the dyno and see how much power we're actually starting with today.
37:35 Looks like a nice smooth curve.
37:39 Which is certainly what you hope for with a stock tune but you never know until you run the car and find out.
37:45 And it looks like we've made peak engine power of 534 and peak torque of 529.
37:53 The curve looks nice and smooth, I don't see any big drops that indicate there's any knock occurring, any misfiring, anything of that sort.
38:01 So it looks like we're good to go and start applying our changes.
38:05 Since we've made this airflow change, we're going to expect the car to lean out a little bit and I opened the fuelling about 4% so while it doesn't perfectly translate in terms of air/fuel ratio decimal value, a 4% reduction in MAF scaling will typically result in a 0.4 higher gas AFR measured value.
38:30 So for example, what does that mean? If we look here back in our log, right here where we have a measured value of 10.86, I'm expecting that to be about 0.4 higher after we apply this change, so somewhere around 11.26.
38:51 Again just a rule of thumb, just gets you in the ballpark, don't expect that to be spot on.
38:58 It also changes depending on the scaling that you're using.
39:02 So for example if you're on an ethanol scaling, the result will be a bit different.
39:08 Another thing I noticed is that peak power occurred right at the end of the dyno run.
39:13 What I don't want to do is show a gain later today by basing it on not showing the full potential of the stock tune.
39:20 So let's give the stock tune another run, not only to get it warmed up and see if any additional power comes from putting some heat in the motor, or if that additional RPM allows the engine output to continue to rise and gives us a higher peak level.
39:36 What we don't want to do again is demonstrate an improvement solely based on not showing the full potential of the factory calibration.
39:44 So on that run we had gone to 6400 RPM.
39:49 Let's go all the way to 6500, we'll likely go right into our rev limiter which we know is going to come in at about 6600 but what we don't want to do is set this at 6600, potentially not quite meet it and then not have the dyno complete the run.
40:04 So we'll go right to 6500 and let's see what happens.
40:09 Before starting the run, just going to save this log file.
40:14 Baseline wide open throttle pull one.
40:23 With that saved, we'll start scanning again.
40:27 Alright.
40:40 On the second baseline, it looks like we've got a similar knock response to the first baseline.
40:45 So comes up, peaks in a similar RPM range, exactly the same amounts, 2.5° knock retard, 4.9° total knock retard.
40:56 Again individual cylinders, reading 0° retard, not actually pulling any timing.
41:03 On the graph, it tapers off, comes down to zeros by 5200 RPM, same point it did on the first run.
41:11 And then on the top end we have no knock response so it looks like that behaviour's consistent.
41:18 At this point, feel free to do more additional baseline runs, see where the vehicle settles in at before making your first flash.
41:26 Now that we've reviewed all our data from our baseline runs, determined which knock is normal and what might be actually concerning, we've seen that our air/fuel ratios are safe but have room for optimisation and everything in general looks safe and ready for us to proceed.
41:45 So let's move on from baselines and setup to MAF scaling.
41:51 in this section, because our focus is MAF scaling, we're going to put the ECU into an operational mode where we disable the dynamic airflow system which is the speed density portion of the equation and focus solely on mass airflow calculated airflow.
42:09 In order to do so, before we get into the MAF scaling itself, let's go ahead and disable the dynamic airflow system.
42:18 In the engine section, under airflow, dynamic, we find the dynamic airflow section and some disable and reenable values.
42:33 So what this first value here does is it disables the dynamic airflow system above this RPM.
42:42 So anything over 4000 RPM we're going to be operating on the MAF only.
42:49 At the moment though we want to be operating on the MAF all the time.
42:53 So how do we do that? Let's drop this value down to zero.
42:58 We'll also set the reenable value to zero and after we flash this to the ECU, we will no longer be operating on the VE model at all.
43:09 Now before I made those changes, you saw the disable value was at 4000 RPM.
43:16 If we go back and look at our baseline, we can actually determine when that switchover happened and see if it lines up.
43:23 So let's do that real quick.
43:25 In your baseline datalog, scroll down in the channels menu until you find air calc mode.
43:32 If we look at the start of the pull, the air calc mode is normal.
43:38 Then as we exceed about 4700, 4800 RPM, we enter high speed mode.
43:50 Now high speed mode continues from there all the way until the end of the run.
43:55 High speed mode is the MAF only operation, normal mode is a hybrid of MAF and speed density based on the virtual VE system.
44:05 Now while this doesn't transition right at 4000 RPM as we saw in the table here in VCM Editor, we understand that sometimes there are transitions, delays and such that aren't necessarily exposed in the tuning software but may occur.
44:24 And those likely account for the slight discrepany between the RPM we expect that system to switch off at and where the monitored value actually changes in the datalog.
44:36 Since we've made some additional changes on top of our first modified calibration, I'm going to save this as modified1A.
44:48 So I'm going to retain the number 1 because when we do our power pull on this, it's going to be our first set of power pulls bit I want to designate it with a letter and mention that we've done some MAF scaling and this is going to be MAF only.
45:08 Now that we've made changes to the MAF calibration, and the factors that enables the dynamic airflow system, let's just double check and make sure we haven't managed to make any other unintended changes.
45:21 Again you can always do this by running a comparison, or run it against our modified setup file.
45:31 And in the comparison log we only have our dynamic airflow, RPM enable value changes and our MAF scaling changes.
45:40 So we are ready to go.
45:43 Let's get the vehicle turned off.
45:50 Turn the ignition back on.
45:56 Before we flash we need to make sure that our VCM Scanner software is not connected to the vehicle.
46:04 If the connect to the vehicle icon is illuminated, the scanner software is still attempting to communicate with the ECU which will prevent the VCM Editor software from flashing it.
46:15 So if this is illuminated, click this button to disconnect from vehicle, then you'll be ready to go.
46:22 I'm already disconnected so we won't run into that.
46:25 To proceed with flashing, we click write vehicle and at this point you're presented with the vehicle writer.
46:34 As long as you've licensed this ECU already, and have the corresponding download plug in, you won't have to license it again at this time.
46:42 If you have not yet licensed the vehicle, you will be prompted to do so before you're allowed to flash any modified calibration to the vehicle.
46:51 We're presented with a pull down menu which has multiple options including write calibration and write entire.
46:59 For the purposes of this course, we're going to write calibration.
47:02 This will apply all the changes we intend to make without writing areas of the ECU that we do not need to modify.
47:10 This will both save us time due to shorter write times, as well as avoid taking unecessary risks writing portions of the ECU which may be susceptible to causing a problem which could result in the ECU being in a state which will require recovery and potentially prevent the ECU from allowing the engine to start.
47:32 Again you may find a certain specific situation where you need to perform a write entire but that is beyond the scope of this course.
47:40 So let's proceed with write calibration.
47:44 While write entire may take several minutes, similar to the amount of time it took to read the entire ECU, writing the calibration, as you can see, takes less than a minute in most cases.
47:57 Write has complete, we're going to close.
48:00 After flashing the ECU, it's critical that you allow sufficient time for the ECU to reset.
48:06 So power it down, then wait.
48:10 I suggest waiting at least 20 seconds.
48:13 On this vehicle, the cluster actually shuts off as it's just done and at that point I'm fairly comfortable that when I power it back on, the ECU will have reset.
48:23 All changes we intend to apply will have been applied.
48:27 As an additional safety precaution, some tuners choose to open the driver door and then close it again which can also power off and power back on other various potentially associated modules in the vehicle.
48:42 So let's go ahead and power the car back on.
48:50 And then we'll start it up.
48:56 We'll switch back over to our scanner software.
49:04 If you encounter a situation like this where the option to connect to vehicle is not present, my suggestion is to close the software and simply reopen it.
49:18 Of course that assumes that your dongle is plugged in, mine is so in this case close the software out, open it back up, that's illuminated, allows me to connect vehicle, we're back in business.
49:33 So now that we've connected, start scanning and we'll give the vehicle a moment to stabilise and then we'll see where we are in terms of our fuel trims.
49:43 So far it's looking like bank 1 has a trim of 0, bank 2 has a slight positive trim and that's certainly an improvement from what we had before.
49:57 We'll go back to our long term plus short term trim monitoring and looks like we have values of approximately 5 at idle.
50:09 Engine's still warming back up as we've spent a little time flashing and preparing for this flash.
50:17 So once we get fully warmed back up, let's see where these settle in and we'll go from there.
50:23 Due to the cold weather we're experiencing here, it's taking quite a bit of time for the engine to warm back up just idling so I'm going to get it in gear, start rolling it.
50:35 And let's get some heat into it.
50:40 I'll do that just by cruising it.
50:53 And then again we'll keep watching our long term fuel trim plus short term fuel trim graph.
50:58 And see what types of values start populating in the table.
51:13 So where before we were seeing more significantly negative values, now we're seeing more reasonable ones.
51:29 Alright now that we're more up to operating temperature I'm going to swing through the range again.
51:40 So just applying throttle to gradually walk our way up in airflow and RPM.
51:53 And this is looking pretty good already.
52:14 So since we've done some baseline full throttle pulls, now I'm more confident that I can walk through higher RPM ranges without concern for damage to the engine, knowing that we'll be on our air/fuel target so just going through one more time, gathering a bit more data, just to confirm our findings.
52:41 And as you can see, each time I do this, the result is slightly different.
52:46 So as we gather more data, we can become more confident in the future changes we want to make.
52:52 Now that we've roughed things in with that initial 4%, we really want to dial it in a bit more precisely.
53:06 OK so I'll stop my datalog.
53:10 And then as we look at the data, it looks like on the top end, we're getting pretty close to our target, corrections are relatively small.
53:23 So at this point, I'm not going to make additional changes in that area.
53:29 But underneath that, it looks like we still have a relatively consistent negative trim.
53:35 Looks like we could take a few more percent out.
53:41 And down here in this range, significant negative values but a few positive values.
53:50 Now these realistically are mostly transients however this area, we'll need to spend a bit more time in.
53:58 And at that point we'll be able to determine what we need to do there.
54:03 First though, let's work with the data we do have that we're feeling more confident in.
54:09 So that's going to be here from 2700 up to about 5500.
54:16 So we'll go back to our VCM Editor software and I'm going to focus on this area, from 5700 to 2700 based on what we found during our data gathering.
54:45 And I'm going to take 1% out here.
54:55 Then I'm going to take an area one cell smaller on either end and take another half a percent out.
55:09 And then go one cell smaller again, take another half a percent out.
55:16 So I've taken a total of 2% out of the area that's currently selected.
55:21 1.5 out, out to here and then only 1% out this far.
55:27 Now the reason I've done this is I really attempt to blend in any changes I make to MAF scaling so that they aren't abrupt and again that's why I keep the graphical representation up on the screen as a visual reminder of that fact.
55:42 Again any abrupt changes in the MAF scaling can cause abrupt transitions in fuelling which can be felt to the driver as a lack of smoothness and that's something that we always want to avoid.
55:54 A good calibration to drive as smooth, if not smoother than stock, based on being fully optimised for that vehicle's setup, local conditions and fuel.
56:04 At this point I'm going to go ahead and save this file as modified2.
56:13 Again the change we made was primarily MAF scaling so I'm going to note that again, and save.
56:20 Now at this point, let's go ahead and gather more data in this lower range where we seem to have some significant negative values, a couple of stray significant positive values, let's try to make better sense of what's going on there.
56:39 So at idle now we're seeing some negative trims that are actually somewhat sizeable.
56:43 Few moments ago I saw some in that area that were actually positive.
56:48 Since this is going a bit back and forth, I'm not too keen on adjusting that area.
56:53 What I do want to get into is the area just below it in this range which seems a bit volatile and let's just see what happens there.
57:06 So I'm easing off the throttle and back on.
57:11 And it looks like with really smooth inputs, seeing some pretty consistent values here actually.
57:21 OK now that we've spent a bit more time on this area, I'm not seeing those errant values we were before and I think as I mentioned those were likely transient related.
57:33 These values are actually quite small and I'm very happy with them so it doesn't look like I'm going to be making any more changes in that area.
57:46 I do see a bit here just under 2700 so let's let the car come back down to idle, yeah and there you can see on decel, some significant trimming but in a transient situation like that, you don't want to make MAF scaling adjustments to create a better trend during a transient, which will actually negatively impact steady state operation.
58:16 In the situation of MAF scaling, I always err on the side of calibrating towards excellent fuel trims during steady state and allowing transients to be handled by functions made for transient behaviour.
58:28 Such as the virtual VE system, tip in enrichments if present and wall wetting compensations, again if present.
58:35 So let's stop the log there and it looks like we've gone back to a positive trim at idle.
58:47 So as we saw a moment ago, we were seeing values of -8, -10 in the idle area, now +4.
58:54 If they're going back and forth between positive and negative, I'm not really too keen on swaying the fuel trims in either direction.
59:02 As long as it's centred mostly around a near zero value, I'm going to leave that as it is.
59:08 So what I do want to do is take a look at this area just below the range we stopped making our adjustments at and tweak those a little bit now.
59:20 So if we go down here for example, we stopped our correction at 2700, next value is 2624 and here we're seeing we still have a pretty significant at least repeatable negative trim so I'm going to take a little bit out of there and blend that correction down a bit.
59:48 When I say blend down, what I mean is I'm going to take 1% out here.
59:58 I'm going to take 1% out here.
01:00:03 And then in this section, we're going to take out 0.5%.
01:00:08 A 1% correction might not seem like a lot and maybe you're wondering why I'm bothering blending it in but I feel like it's a really good habit to have.
01:00:17 That way as you get into larger corrections, you're reminded this is the correct process and you'll always end up with a nice smooth curve.
01:00:26 I'll go ahead and save.
01:00:29 And at this point I'm pretty happy with this set of adjustments, I don't want to do anything more at this time that might muddy the water and make it unclear how our changes have impacted the result.
01:00:43 Let's go ahead and flash this to the vehicle and then run it and see what we get at partial throttle.
01:00:50 Then if things are looking really good, we can go straight into a power run without doing a separate flash and set of adjustments.
01:00:57 As long as we're close enough.
01:00:59 So let's shut the vehicle off.
01:01:06 Turn the power back on.
01:01:11 Before we do this, let's remember to disconnect from vehicle in our scanner software.
01:01:20 Now we're ready to write calibration.
01:01:23 Again always write calibration, not write entire, unless you absolutely have to and that's something you can always double check on with HP Tuners directly.
01:01:33 There are some situations where write entire is required but unless it's required, write calibration.
01:01:48 Alright so that's completed, we'll close that out, turn the vehicle off and we'll let it shut itself down.
01:02:02 Go back to our scanner software.
01:02:11 Power back on.
01:02:17 Now while you can connect to the vehicle then start scanning, you can also simply click start scanning and it will do the full process for you.
01:02:36 Alright so this time on startup it looks like we have a net trim of somewhere in the ballpark of 0-3%, very minimal.
01:02:52 Let's get the car rolling.
01:03:38 Things are looking pretty good, we have some small negative numbers, some small positive numbers, really nothing of concern.
01:03:48 At this point we're well within a +/- 10% total trim range, in most cases +/- 5.
01:03:56 I'm very happy with this so we're going to go ahead and proceed to a power pull and that way we'll get to see what happens in open loop.
01:04:05 We'll see where our commanded air/fuel comes out to compared to our wideband measured actual air/fuel.
01:04:13 Alright so I've got the car up into fourth gear, prepared for a pull.
01:04:20 Start recording the power run and now at this point remember we're going to be going into open loop, we don't need to watch fuel trims so much, let's watch our wideband reading and our knock readings.
01:04:31 We know what to expect in terms of the knock reading at the beginning of the pull, let's just make sure we don't see any additional or new knock on the low end or on the top end.
01:04:41 Additionally in terms of our air/fuel, let's hope that the wideband reading will be relatively similar to the air/fuel command once we get into a power enrichment open loop state towards the middle of the pull.
01:04:56 From then onward we should see numbers that are relatively in the ballpark of similar.
01:05:02 Here we go.
01:05:16 Alright so let's take a look at our dyno graph.
01:05:23 And I'm going to name this modified2 to correspond with the file name of our calibration.
01:05:36 The reason I like to do that is just to make sure I can go back and determine what the result was for a given set of calibration changes.
01:05:46 Now as we can see here, we've actually made a relatively substantial gain already and I believe this is related to the MAF scaling we've performed, providing us with a more accurate representation of airflow which has allowed us to achieve the air/fuel targets that are actually being requested.
01:06:06 So this is a situation where we haven't actually requested a different air/fuel target than what it was stock but what we have done is corrected the mass airflow scaling and because in this case, correcting it meant removing values, or reducing values, from the MAF scaling which results in a leaner air/fuel mixture, more to target and that slightly leaner mixture has resulted in the power gain we see here.
01:06:34 So at this point, we've got a pretty solid gain, let's make sure that this gain is safe though.
01:06:42 So as we look at our log, on the low end of the pull, we see the knock response we're used to, as I'm scanning through I'm also watching these knock retard cylinder values to make sure they're all zeros and they are.
01:07:06 And the peak knock retard and total knock retard again, 2.5 and 4.9, nothing new there so that's good.
01:07:16 That goes down to zero right around 5200 RPM again and then from then on out, zero knock so we've leaned the car out a little bit, can see it here in the wideband reading, being a lot closer to the command.
01:07:31 Got around 11.4 on the wideband, 11.7 on the command.
01:07:35 Now I know this is a little bit confusing but if we go back to before the pull, what we're seeing here is a command of 14.11, wideband reading of 14.5, there is a discrepancy there because the AFR command is based on an E10 scale.
01:07:54 The stoich point of E10 being 14.11, this is actually a lambda command of 1.0.
01:08:02 However our wideband is being represented to us on the gas AFR scale for E0.
01:08:10 So these values right here are actually almost identical but are being displayed on a different scale.
01:08:19 So down here, just keep in mind we aren't operating on the exact same scale.
01:08:27 Now I've displayed this in air/fuel ratio because that's what's going to be most common to folks who are tuning this system, however if you're comfortable with lambda, this is an instance where I really suggest using lambda based values as they'll remove some of that discrepancy and make things a little bit more clear.
01:08:47 Even in AFR, what we can see is rather than being in the 10.8, 10.9 range, we're now around 11.4 so we've leaned out right around the 4/10ths that I expected based on our initial 4% correction that went all the way up to the top end of the MAF scale range which is where we're operating in this portion of the dyno pull.
01:09:11 Now I can confirm that and let's go over here.
01:09:21 And we'll go to our mass airflow sensor.
01:09:26 And the frequency value here in the 9000 to 10,000 range so well well well beyond the range we made the additional adjustments, beyond 4% at, which stopped right around 6000, 7000 right so up here we're only getting into the range where we made that initial 4% reduction.
01:09:49 Other than that, let's see how much boost we're making.
01:09:56 So on the top end, right around 177 kPa, again if you're not familiar with kPa, unit conversion can come in handy.
01:10:10 So about 25.6 psi and again this is an absolute reading so just keep in mind we aren't actually making 25 pounds of boost, we're making about 10 pounds of boost.
01:10:23 So remember to subtract your barometric pressure value from your manifold absolute pressure value to get your boost pressure value which is relative to the atmospheric pressure.
01:10:36 At this point we've already see that we've increased power and torque across the entire RPM range so it's unlikely that we're running into any sort of torque reductions but let's take a look at our torque values and just confirm we're not getting near any limits.
01:10:52 So down here we have our actual engine torque in white, peak torque value in green and max torque in red.
01:11:00 Again what we want to see is a buffer of at least about 100 between the engine torque value and the peak torque value.
01:11:11 And these values, if you compare them to our baseline run you'll find are essentially the same.
01:11:18 Now how is that possible if our dyno is showing an increase in torque which is actually quite significant.
01:11:26 Well the torque model in the ECU doesn't necessarily know that we have increased power because the way we've done it is via the MAF scaling right so we've actually made the vehicle think that it's receiving less air than it initially did on the baseline run.
01:11:45 The new value it's seeing is actually more correct and that is why we have reduced fuel trims which are closer to zero and we're closer to our commanded air/fuel in an open loop situation as well.
01:11:58 So now what we actually have is more accurate airflow modelling but compared to our baseline, we're interpreting what's going on as less airflow.
01:12:10 So we've leaned the vehicle out and we've made more torque but we actually have fooled it into thinking it's making less airflow than before so that is why the torque monitored has not increased the way the dyno has shown the actual vehicle output has increased.
01:12:29 With that in mind, we're well below our limits.
01:12:31 Now another limit which might come into play would be pressure based.
01:12:38 So we know how much pressure we're creating, let's go back and take a look at pressure limits in the ECU to see how close we are to them.
01:12:48 So under torque management, let's take a look in the supercharger or turbocharger boost control setting at the boost max limit.
01:12:58 Now as we saw, we were getting up to about 178 kPa, this table is in the same units.
01:13:05 It looks like if we were in extreme cold temperature condition, we might be near a limit but otherwise, we are well under it so it does not look like we need to update that table at all.
01:13:23 Under the supercharger setting, max pressure 180, now that, we are right up against that so let's go ahead and bump that up a little bit, just in case we're in a scenario where we can flow enough air to actually go beyond that limit, let's go ahead and take advantage of that and let it happen.
01:13:43 Now in a turbocharged situation, you're probably going to lean on this a little more heavily, in our case because we have a supercharger, there's really only so much difference we're going to see in this over time, we're already at a relatively low elevation, barometric pressure can't get much more favourable.
01:14:01 It's also pretty cold today so that can't get much more favourable either so it's unrealistic we could ever get anywhere near let's say 190 kPa but I'm going to give us just a little extra buffer just in case.
01:14:15 Now if you've gone ahead and changed your pulley system and you're creating significantly more boost, you'll absolutely need to change this as well as some of the other settings.
01:14:26 Again in a turbocharged application, first thing you might be doing after you get through MAF scaling at stock boost is bumping the boost up so again this is something you're going to want to look at right away and dial in based on the amount of boost you're looking to increase.
01:14:44 Typically you'll want to leave that a little bit safe so that if your boost control settings aren't quite spot on to begin with, you have a nice safety measure to keep things in check and allow boost from running away, potentially causing engine damage.
01:14:58 Now that we've got the MAF pretty well dialled in, we're going to move on to optimising other things such as spark advance.
01:15:04 At this time though, I'm going to leave the dynamic airflow system disabled.
01:15:09 That way while we're working on other things, we continue to focus on the MAF being the source of air mass calculation.
01:15:18 That way if anything comes up and we need to make an adjustment, we can do so knowing that we are only working of the MAF.
01:15:28 Once we have ignition timing and other items dialled in, then I'll bring the dynamic airflow system back in and we'll put it all together at the end.

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