Practical Standalone Tuning: Step 7: Steady State Fuel Tuning
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Step 7: Steady State Fuel Tuning
30.58
| 00:00 | - We're now at the point where we can begin the dyno tuning process and we're going to begin this with our steady state fuel tuning. |
| 00:07 | Before we jump in though, I just want to discuss a couple of idiosyncrasies that we need to understand with the VTEC mechanism and how that's going to impact on our tuning, so we'll just cover that off now. |
| 00:18 | In the body of the course, I recommend that we steady state tune in fuel and ignition for that matter, out to about 2/3 of the rev limiter, so typically somewhere around about 4500 RPM or thereabouts. |
| 00:30 | Now with the VTEC mechanism there's not a lot of point doing that or being really thorough at higher RPM because we may end up finding that we're optimising the area of the map that we're simply never going to run in. |
| 00:42 | For example if we find that our VTEC mechanism does want to switch at 4000 RPM, then there's no point optimising our VE table at 4000 and then 4500, maybe 5000 RPM on the low cam setting when we're never actually going to operate there. |
| 00:58 | So I'm going to simplify this a little bit here during this step and we're only going to go out to 4000 RPM. |
| 01:04 | May still prove that that's not quite right but we'll be able to come back and address this, fine tune it once we've gone through and optimised our VTEC changeover point and we do that in our full power ramp run tuning. |
| 01:16 | So there's a bit of toing and froing or iterative process here between our steady state fuel and ignition and our wide open throttle tuning. |
| 01:23 | What we're quite likely going to have to do is come back and extend our steady state tuning or fuel and ignition out into those higher RPM areas once we actually know where that VTEC changeover point is going to be but you'll see as we go through this, how exactly we can address that. |
| 01:39 | Now as part of this, what we also want to do is make sure for the moment that our VTEC is not switching over. |
| 01:46 | You'll remember when we were configuring our base map, we had set the VTEC changeover point at 4000 RPM so what I'm going to do is just temporarily move that higher in the rev range just essentially up and above the point that we're going to be tuning to so let's do that now. |
| 02:00 | We'll come into our outputs and what we want to do here is look at our user output one VTEC, we'll click on that there and we'll see that that is still set to 4000 RPM so we can simply move that out to 5000 or something of that nature. |
| 02:16 | Just getting it above the point that you're going to be tuning so there's no danger of that switching. |
| 02:20 | Alright so coming back to our VE table, I'll just cover off what we're going to do here. |
| 02:25 | We're going to start at as low in the RPM and load as we can realistically get to. |
| 02:29 | Let's say that that's going to be 1500 RPM and we might be able to get down to maybe 25 or 30 kPa. |
| 02:37 | The reason we can't completely tune the column at 1500 RPM is simply because if we keep backing off the throttle, which we need to do in order to get down lower in our manifold pressure in VE table, at some point we're simply not making enough torque to actually operate the dyno so the engine simply slows down. |
| 02:55 | We'll see how we can extrapolate those values though as we go to fill out the areas that we can't get to. |
| 03:02 | So what we're going to do is let's assume we can get down to 30 kPa, we'll tune that cell and then what we're going to do is increase our throttle opening and move up the 1500 RPM column, basically tuning those cells as we go. |
| 03:13 | Now it's also worth just talking about the process that we go through here because we've obviously only taken a stab in the dark here with a number of 50%, we've made some big bold changes here or block changes I should say, in the idle area just to get our idle mixtures where they need to be but essentially at the moment the table is untuned. |
| 03:34 | So it's likely that as we increase our throttle opening we may find that we are too rich or maybe too lean and what we can do is as we start filling in this table and moving up the load, if we see that we're too lean at one cell, we fill that in or optimise that cell, then chances are as we then move up the load into another cell, generally as we open the throttle we would expect the volumetric efficiency to increase, so we know that if we're already lean in the cell that we've just tuned, as we increase the throttle, we're most likely going to be leaner again in that next cell so what we could do is just start extrapolating those values out, taking a bit of a guess before we get into those cells. |
| 04:12 | It's not going to be perfect but it's really easy to fine tune and then we're going to be closer to the mark and this is going to be quicker and also put less stress on the engine. |
| 04:21 | Not such an issue here for our naturally aspirated B18C but particularly with more highly strung naturally aspirated engines and definitely with turbocharged engines, as we get up in the load and the RPM it is better or recommended not to run the engine too lean for extended periods of time, obviously that can be dangerous. |
| 04:39 | And we'll see exactly how we can cope with that as well as we go through. |
| 04:43 | OK couple of other things I just want to mention here is the way we can make changes to the cells. |
| 04:48 | Now you've already seen some of this anyway, I'll just reiterate, let's just select a cell there, so first of all we can directly enter a value, let's say we want to change that cell to 60, just enter the number and then press the enter key, job done. |
| 05:02 | Now the other way we can do this as we've already seen is using the plus and minus key to make 1% changes, the shift and plus and minus to make 5% changes so really easy to make quite fast adjustments. |
| 05:13 | And then control plus and minus to make 0.1% changes if we want to fine tune the cell that we're in. |
| 05:20 | Now we can also use a MAF function so let's say we ware 12% lean, well what we could do is enter a value of 1.12 then the little asterisk or multiplication symbol, press enter and that will make that 12% adjustment to our fuelling. |
| 05:34 | The last way that we can also make changes, and we're not running the engine at the moment so I can't show you this but we'll see it once we get up and running, is using the control T function and that is an autotune function. |
| 05:46 | Essentially what it does is it takes the difference between our measured air/fuel ratio or lambda and our target and we'll make a correction based on that. |
| 05:55 | Now that we know how we can make these changes, and again you'll see them in action, let's get ourselves up and running, we'll get ourselves up to temperature and we can have a look at the actual tuning process. |
| 06:06 | Alright we've got our engine up and running, temperatures are in the operating region but before we actually start running the car on the dyno, just another couple of elements that I want to talk about here. |
| 06:16 | We can see we've got this little blue cross hairs showing where exactly we're accessing in the VE table at any point in time and right beside this, it's very difficult to see, we've got a little blue lambda symbol and that shows the current lambda or the air/fuel ratio that is being measured by our wideband, that is simply the same as the number being shown down here in our gauge bar. |
| 06:37 | Now as I mentioned, pretty difficult to see, not that useful during our tuning process. |
| 06:43 | What I'm going to do is come up to the right hand top corner, press the 2D plus 3D and that's going to give us our 3D representation at the same time as our 2D table. |
| 06:52 | Now we see a little blue dot showing where we are accessing, that's the same as our cross hairs, we've got a little bit more information now and we can see the lambda as well as the target lambda which is in brackets beside so we've got that reference. |
| 07:06 | Now I don't tend to use that, it's personal preference. |
| 07:10 | What I have done is actually added the target lambda down in our bottom gauge bar there right beside our lambda so that I've got that as a reference because we obviously always want to be referencing what our target lambda is when we are actually making tuning changes so we know when we're on track. |
| 07:27 | Now if you want to add a gauge down here, all we need to do is choose where we want it, right click and then we can click add and remove items and then we would simply search for what we want. |
| 07:39 | In this case if we type in lambda we can see we've got our options there, the one that we do want is lambda target, I've clearly already got that ticked because it's there. |
| 07:48 | Ticking that box and clicking OK would add that gauge but again we've already done that. |
| 07:53 | Alright so let's get ourselves up and running at 1500 RPM, we'll get ourselves stable in the lowest load cell we can and we can start making our tuning changes. |
| 08:03 | Alright so we are now in the middle of our 30 kPa, 1500 RPM cell and what we can see is our lambda is a little bit leaner than our target. |
| 08:14 | We're sitting at 1.01 and our target's 0.95. |
| 08:18 | Now yes we are lean at the moment but there's essentially no load on the engine so I'm certainly not worried about that but let's have a look at some of our options to make our tuning changes. |
| 08:28 | Now we've already looked at the plus and minus so let's have a look at using the correction factor calculation that we learned about in our EFI Tuning Fundamentals course. |
| 08:38 | So what we'll do is bring up our calculator function here and what we want to do is enter our measured lambda, so 1.01, it's moving around a little bit but 1.01, probably closed to 1.02. |
| 08:51 | Let's enter that, want to divide that by our target, in this case 0.95 and that gives us a correction factor of 1.07. |
| 09:01 | Essentially what we need to do is add 7% fuel to that particular cell. |
| 09:06 | So let's go ahead and do that, we'll enter a value of 1.07, enter the multiplication symbol, press enter and that should correct our air/fuel ratio, we can see that it's done a pretty good job but it's still not quite there, we're still a couple of percent lean. |
| 09:21 | Now we'll just talk about that for a moment because this can be a little bit of a warning sign. |
| 09:26 | If we make this correction and it doesn't correct all of the error, there could be a possibility that we've either got a problem with our injector characterisation data, for example if our injector deadtime values are incorrect, that can result in this sort of error, the correction factors won't work as they should. |
| 09:45 | Potentially we could also have some problems with our fuel characteristics but a small amount of error here is not unexpected just mention that is a potential warning though in some instances. |
| 09:56 | So we're still a couple of percent lean there, let's have a look at fixing that, let's just add manually 2% to our fuelling and we're on our target so job done there. |
| 10:08 | So we've gone from 34% in our 30 kPa cell there to 38% and now we're going to increase our throttle opening and we're going to move up to our 40 kPa cell. |
| 10:22 | The number in there's 50, it's enough of a jump, I'm expecting we're probably going to find we're a little bit rich but let's just increase our throttle opening and see what happens. |
| 10:31 | Again really important to make sure that we use that crosshairs to be as accurate as we can about making sure we're in the centre of the cell. |
| 10:39 | If we're not in the centre of the cell when we make our tuning changes, then we're going to find that we're interpolating with the surrounding cells and that's going to obviously affect the accuracy of our tuning so really important just to take the time to make sure that we're as close to the centre of the cell as we can. |
| 10:54 | Now looking at our lambda at the moment, we're sitting at 0.91, 0.92, target 0.95 so we're a few percent off our target there so let's try using our control T autotune function so I'll just press that, it will make the tuning change for us and we can see that we're almost right on our target in one iteration. |
| 11:15 | Still just a touch rich so being a little bit fussy here, we'll just use the control and minus and remove a couple of points of a percent there of fuel until we're on our target, job done. |
| 11:26 | Alright, also worth mentioning here that when we are doing our fuel tuning, the lambda that's being measured is always a moving target, it's always moving around a little bit so don't need to beat yourself up too much, if I'm within about plus or minus 0.1 of my target lambda, I'm going to be pretty happy with that. |
| 11:42 | We're tuning in air/fuel ratio values instead of lambda, again if I'm plus or minus about 0.1 from my target, I'm going to be OK with that. |
| 11:50 | Alright so again, let's increase our throttle opening, we'll move up to our 50 kPa cell and see what our lambda looks like there. |
| 12:00 | So now we've moved a little bit leaner than our target there, our target's still 0.95, remembering that we are down in our 1500 RPM column here so we're quite low. |
| 12:09 | So what I'm going to do because we are quite close there, just adding 3% manually to our fuelling and maybe removing a couple of points there, we're right on our target so we're pretty good to go. |
| 12:20 | Now we're in one of those situations where we can start extrapolating a little. |
| 12:23 | We've just increased our fuelling there to 52, 53% in that cell at 50 kPa. |
| 12:29 | Obviously above this at 60 kPa we've still got a value of 50, chances are we're going to expect the engine to be lean if we just open the throttle. |
| 12:38 | Now there's nothing particularly wrong with doing that, given our low power and low RPM setting. |
| 12:43 | Let's just take a bit of a guess here, we've gone from 48%, 47.8% to 52.7% so we've gone up about 5% there so let's just take a guess at 58%, don't have to be too accurate here but it should get us pretty close to the mark. |
| 12:59 | Let's open our throttle again, move up to 60 kPa and we'll see how close we were. |
| 13:05 | And we can see we've actually overestimated, we're a little bit rich but always safer to be a little bit rich than start a little bit lean so I'll just pull a couple of percent out there manually and again everything's moving around a little bit but we're pretty much close to our target. |
| 13:18 | Now what we can do is again just follow this process through, so I'll just take a guess here that 80 kPa might want to be 62%, we'll open our throttle again and it actually was a pretty close guess, we're still a little bit rich there, I'll just pull a little bit of fuel out and we're pretty much on our target now, 61% there so let's go up to 65% at 90 kPa, open our throttle. |
| 13:45 | And we can see that we're a little bit too rich, that's OK, we'll just pull a little bit of fuel out using our minus key and now let's open our throttle all the way and we're going to see that we won't actually be able to get into the centre of our 100 kPa cell so let's just try that. |
| 14:00 | Pretty close but due to our ambient pressure here, 97 kPa's as far as we're going to get. |
| 14:08 | We are lean and we expected that because I didn't guess ahead. |
| 14:11 | So again, not a problem here, low power but let's take a guess there, 65%, got a little bit too far, let's just take a couple of percent out again manually. |
| 14:25 | And we're on our target right there. |
| 14:30 | OK let's come back to an idle and we'll just have a look at what we've just experienced, what we've learned there. |
| 14:36 | So we've gone through and optimised our tune there on our 30 kPa, from 30 kPa through to our 100 kPa site at 1500 RPM. |
| 14:45 | And that leaves us with a bit of a problem because there's this area here that we can't get to, basically we can't get down that low in the load. |
| 14:54 | Now there's an aspect here that if we can't get to it on the dyno, it's going to be difficult to get to on the road but on the road we could get into a situation where maybe we're rolling down a slight hill and we're in gear and we can back out of the throttle and that could let us get down a little lower in the load than what we can get to on the dyno so we can't just leave these areas untuned, we want to take a bit of a guess at what these numbers should be and then once we've filled this in, then we can optimise and confirm these values when we do complete our road tuning or our racetrack tuning as the case may be. |
| 15:29 | So let's have a look here at what we've experienced so we know we've gone from essentially 38% here to 48% so we've actually gone up basically 10% over 10 kPa. |
| 15:40 | It's quite a jump there, let's have another look here, from 40 kPa to 50 kPa we've gone up from 48% to 53% so we've gone about 5% so we've actually got quite a variation here and if we look in our graphical representation, we can see it's starting to drop quite quickly. |
| 15:57 | Now again I'd always like to be a little bit safer when I start my tuning and then we can basically optimise that as we see fit, it's going to be safer than starting a little bit lean or at least in this case safety's not an issue, we're not going to damage the engine at such light load but the engine will run nicer or smoother if we're a little rich compared to if we're a little lean. |
| 16:18 | So what I'm going to do here is just manually take a bit of a guess here. |
| 16:21 | So we've gone down 10% over the 40 to 30 kPa. |
| 16:26 | I might want to start by actually only reducing it 6-7% so let's go in our 20 kPa site here, gone from 38, let's go down to 32%, so essentially we're taking a guess of 6% per 10 kPa instead of 10. |
| 16:43 | Now this leaves us with the site in between here. |
| 16:46 | It's important to know that our break points aren't even, we've actually got this break point in here at 25 kPa so we know that this is going to essentially be the mid point, about 3 kPa, what we can do is use another feature in the maps here, we can highlight those cells and then we right click and then we can use the interpolate vertical function and that'll do the work for us. |
| 17:06 | So again what I'm going to do here is just take that same sort of guess, maybe 5-6%, maybe I want to roll this off a little bit here and we're just going to continue down so let's take a guess here that we might want to be about 26% for this cell and we're going down another 10 kPa, not that we're ever going to get down to zero but let's maybe make this cell 21%. |
| 17:31 | Now what we also can see now, and this is the benefit of using the graphical representation in here is that one column that we've tuned is pretty smooth now, we've got a nice consistent trend which is exactly what we'd expect. |
| 17:44 | As we increase our load, we're increasing our fuelling so pretty happy that that has got us on the right track. |
| 17:50 | One thing I will note here is that in our 80, 90 and 100 kPa cells, we do have this little idiosyncrasy here, we've got a bit of an outlier at 90 kPa where we've stepped up to 62% VE and then when we go further at 100% throttle, we didn't quite get into 100 kPa, we got up to 97 and we've actually dropped back. |
| 18:13 | Now 1% there, I'm not too worried about that but this is something to look out for when you have completed your steady state tuning. |
| 18:20 | If you've got a weird outlier that doesn't follow the consistent trend of the rest of the table, this would be an indication to look a little bit deeper, maybe go back and revisit that site and just make sure that your tuning was in fact on point. |
| 18:33 | OK at this point though we've completed our 1500 RPM column so what we're going to do is highlight that column just using our shift and arrow keys, I'm going to control C to copy that, we'll right arrow to move across to 2000, control V, we're going to paste that into our 2000 RPM column and we can essentially repeat the process. |
| 18:51 | Now before we get started though I am going to take a bit of a stab in the dark here that as we go from 1500 RPM to 2000 RPM, I'm going to expect our VE should probably be increasing and because our VE should increase, the numbers in our VE table should also match. |
| 19:08 | If we don't do this, what that's going to mean is that when we get to our 2000 RPM column, we're probably going to be a little bit lean so let's just guess ahead here, doesn't really matter, doesn't have to be correct but let's add 5% and I'm going to do that by entering 1.05, the multiplication symbol, press enter and that's done that for us. |
| 19:28 | Alright let's get ourselves back up and running, 2000 RPM and we'll have a look and see how close our guess was. |
| 19:37 | Alright so what we can see here is that I've just gone into 40 kPa at the moment and our guess was a little bit optimistic, we're actually running about 6% richer than our target. |
| 19:49 | Before I start making individual cell changes though, what I'm going to do is make an across the board change to that entire column while it's still highlighted. |
| 19:58 | The reason I'm doing this is because if we're following the trend from 1500 RPM, then if we're lean or rich in one cell then we're probably going to be lean or rich in all of them so let's just get our entire column onto the right lambda there using the minus key in this case, gone a little bit too far there, use our control key and add a little bit more fuel and we're pretty much on the money now so now what I'll do is I'll drop my throttle setting, we'll come back down to, make sure we get into the middle of our 30 kPa cell and we can. |
| 20:32 | Just make a small adjustment to our dyno set point to make sure that's nice and accurate. |
| 20:37 | And we can see that we're actually a little bit lean here, about 2% lean so again because we can't get down below 30 kPa, I'm going to make this particular change to the 30 kPa site and the ones below. |
| 20:51 | Again just working on the basis that if we're lean in this cell, the ones below should probably be too lean as well, just get ourselves back on track here. |
| 21:10 | Alright so what we'll do is we'll just add a couple of percent manually to our fuelling, that's done now so now let's come back up, we've already tuned our 40 kPa cell or it should be tuned, we've made that across the board change, I'll just check there, yep that's good, let's come up to our 50 kPa site, get in the centre of that site, very very slightly lean so I'll just use the control key there to add a little bit of fuel. |
| 21:34 | Come up to our 60 kPa site, again we're very very close to our target, we're talking a couple of 10ths there of a percent but if we want to be fussy well we absolutely can be. |
| 21:45 | We'll come up to 80 kPa. |
| 21:50 | And we're a little bit lean here, 0.97 vs 0.95 so let's just add a percent manually using the plus key, pretty much on target now. |
| 22:00 | Now again because I've got this trend, before I step up to 90 and 100%, I'm going to tune ahead here and I know that we were lean in that particular cell at 80 kPa, let's just add one more percent to our 90 and our 100 kPa sites. |
| 22:15 | Alright let's just see what we're like at 90 kPa now, absolutely bang on the money perfect there and just moving around a little bit, probably more veering on the side of being about half a percent too lean so we'll just add a little bit of fuel. |
| 22:32 | Now we're sort of swinging backwards and forwards across our target so I'm happy with that. |
| 22:36 | Again I'll add that half a percent to the 100 kPa site, go to full throttle, see how close we can get. |
| 22:43 | And pretty good there, again we're swinging backwards and forwards, I'm just going to add another couple of 10ths to that particular cell. |
| 22:52 | Alright we'll back off the throttle there. |
| 22:55 | So you can see particularly extrapolating or copying the 1500 RPM column across to 2000, adding a bit of fuel to that, what it meant is that process was quite quick because particularly once we got above 40 kPa, essentially instead of making wholesale changes, we were only making a change of maybe 1% or there abouts at the most so we're very very close to our target before we actually make any tuning changes and it speeds the process up. |
| 23:18 | So what we'll do is repeat what we've done there, we'll copy the 2000 RPM column, control C, control V and we'll move that across to the right. |
| 23:26 | Now again we can just extrapolate or guess at the change we're going to need. |
| 23:31 | From 2000 to 2500 I'm already going to expect we're going to need more fuel. |
| 23:35 | Went a little bit too far this time so we can learn from that, let's try 3% and see how that works, we'll enter the number 1.03, the multiplication symbol and press enter and we're ready to go. |
| 23:47 | From this point we're going to speed the process up though, we're going to now tune the engine under steady state conditions out to 4000 RPM just like youv'e seen me do. |
| 23:56 | Now couple of warnings here, this is more so, once we start getting higher in the RPM and load, particularly with turbocharged engines you may find that you need to keep an eye on your coolant and for turbocharged engines, your intake air temperature. |
| 24:12 | Just make sure that these are both staying within realistic bounds. |
| 24:16 | Sometimes it can be difficult on the dyno to replicate these temperatures that the car will see on the open road and if we're tuning under very unrealistic conditions, this can affect the accuracy of our tuning so sometimes we may need to come back to idle, allow all of the heat soak to dissipate before we continue. |
| 24:32 | So now let's get going, we'll speed this up and we'll come back and we'll look at what we've learned once we've completed our tuning out to 4000 RPM. |
| 25:05 | OK so at this point we have completed the steady state fuel tuning out to 4000 RPM. |
| 25:09 | During that process you essentially would have seen me use all of the techniques that I talked about and really the technique that I choose is going to depend on my personal preference as well as essentially how far away form the mark we are in terms of our air/fuel ratio. |
| 25:25 | The other benefit that you'll see from the technique that I'm applying here in terms of copying our column across and then adding a little bit of additional VE to that column before you move into it is the tuning is very very fast. |
| 25:39 | A lot of the cells that we move through we were making absolutely no changes or if they needed a change, it's going to be in the order of 1% VE or maybe even less. |
| 25:49 | So that's the benefit of this process, it means that we're going to be very very close to the mark before we even get into an unturned cell. |
| 25:57 | Now this does leave us with a couple of areas that are currently untuned though. |
| 26:01 | We haven't been able to tune our high load, low RPM area, we can't really run the engine happily at 750 or 500 RPM at full load on the dyno. |
| 26:12 | However, as you can see where our little cross hairs is sitting right now with the engine not running. |
| 26:16 | we do transition through these areas as part of our startup so we don't want to leave these untuned, we're going to extrapolate the columns across to the left and make some broad assumptions or manipulations to those to suit. |
| 26:30 | Likewise we haven't been able to tune out into our higher RPM area and we're going to be dealing with this as we get into our wide open throttle tuning but before we get there we do want to essentially extrapolate the trends that we've already seen out into that area and apply a little bit of common sense so let's start with that so what we'll do is highlight our 4000 RPM column here and what we're going to do is just simply copy this out into the remainder of our table so let's get that done. |
| 27:03 | Alright so now we've got our table, we can sort of see, at least in the areas that we have tuned up to 4000 RPM, we've got what looks like a reasonably sensible shape to this table, nothing that jumps out as an alarm bell. |
| 27:16 | Now what I'm going to do is take again a bit of an educated guess here based on my knowledge of these engines, we're going to expect our VE to increase and peak and then drop away and I'm going to basically copy out that trend that I'm expecting to see so what we'll do is we'll start by highlighting our 6500, 7000 and 7500 RPM columns and let's start by adding 10% to those, so let's enter the value 1.1 and the multiplication symbol and that will add 10%. |
| 27:46 | Now what we're trying to do is just get the shape of this curve to be approximately what we'd expect, it's never going to be right and that's absolutely fine. |
| 27:54 | But it's just going to get us a bit of a shape that we can start working with as we move into those untuned areas with our wide open throttle ramp run tuning. |
| 28:01 | We'll speed this process up now and I'm just going to continue to add a little bit of shape and we'll talk about our results. |
| 28:17 | Alright we've gone through and added a little bit of shape to our VE table and now if we look at our 3D representation, this is probably a bit more what I'd expect a VE table for this engine to look like. |
| 28:28 | And if we look at our numeric values we can see our peak VE numbers are now sitting around about 105%. |
| 28:34 | Now that's probably a realistic expectation for an engine like this. |
| 28:38 | I will mention here that every VE based ECU is a little bit different so we can't take these numbers for granted as an absolute pinpoint accuracy on the real engine VE but we're probably going to be at least in the ballpark and again it doesn't specifically matter, we'll be able to fine tune this as we go. |
| 28:57 | So that leaves us with our low RPM low load area and basically what we want to do is extrapolate our tuned 1500 RPM column this time across to the left. |
| 29:08 | Before we do this, what we do want to do is just take a little bit of a note of what our tuning is, our fuelling is in our idle areas so we've got 32s and 34s at 25 and 30 kPa and we know we're in that vicinity. |
| 29:22 | So what we'll do now is we'll copy our 1500 RPM column, control C, we'll move across to the left and we will just copy these into each of these cells. |
| 29:34 | Now for the moment what I'll do is again highlight those cells, we now know that in the idle areas we've actually jumped up a bit in our VE so we need to bring these down, back to where they were, so we'll go back to about this point here and we can get the engine up and running and fine tune the idle but that's going to have at least a bit of shape to those columns, particularly in the higher load areas that we can't get to, it should have us at least in the ballpark. |
| 30:01 | So at this point our steady state fuel tuning is complete. |
| 30:05 | One last point I will make and I should have really mentioned this at the start of this module but obviously during this module I wasn't using any audio knock detection and this is of course because I am presenting this worked example. |
| 30:17 | While we are focusing on our fuel tuning here, I still highly recommend that while you're doing the fuel tuning, you use audio knock detection just to listen to the engine and make sure that no knock is occurring. |
| 30:30 | And while we have started with safe conservative ignition timing values, we may still find that we might have been a little bit optimistic in some areas and this could result in some light detonation so if that happens, no problem, just back the engine out, maybe come back to idle, go to the zones that you're operating in in the ignition table, remove another 2-3° of the ignition timing there and then you can come back and complete the fuel tuning. |
| 30:53 | Alright let's move onto the next step of our process. |
