Tuning the Megasquirt (Pt 6.) - Boost Tuning

welcome back to a very special holiday edition of the tuning series all i want for christmas is boost so pour yourself a big mug of eggnog put on your ugly sweater and join me in tuner studio warning ugly sweater should only be worn by train personnel side effects include itchiness heat adjusting derivative laughter and holiday chair welcome back my friends to another episode in the tuning series uh today we're going to be looking at how to check over your car and to get everything set up for tuning in boost that's right over atmospheric pressure of 100 kpa we're talking boost it could be turbocharged or supercharged so this could be if you've just installed a turbocharger or a supercharger in your car but it could also be you've just purchased a new car that is using a mega squirt and you've gotten tuner studio and you want to check everything over this is a very good idea to do even though the previous owner may have been boosting around town you don't know where that car's been and you don't know if you are just a few miles from catastrophic explosion or or you've got another 100 000 good miles inner so with that let's check out all the stuff you need to do to get ready to boost all right so to get started i have downloaded a clean base map and so i've gotten this one off of trubeau kitty.com i'll leave a link for that and if you've been following my mega squirt series i've built one from scratch using those instructions and i have a whole video series to go with it so that you can build one too but uh i'll be working with this and a ms3x squirt and just so that you know i'm using the ultimate version of tuner studio but almost everything you're going to see is going to be available in the free version of tuner studio and most of the screens will apply to older versions of megasquirt like the ms2 or even in some cases the ms-1 there's a few differences in screens how they work but the functionality is largely the same okay first so that we're on the same page let's cover some terminology over here on the left you'll see this fuel load is in kpa kilopascals and this is a measure of pressure and most people are used to thinking of boost in terms of psi pounds per square inch but in tuner studio it uses kpa scale but there's a handy little chart here that if you hover over one of the values it will tell you what it is in psi relative to 100 kpa now why does it say relative to 100 kpa well 100 kpa is atmospheric pressure at sea level so if you're at altitude like you're up in the mountains it'll be a little bit lower of what your normal pressures are so you have to take that into account and if you're below sea level you decided to tune in death valley today then it may be a little bit higher than 100 but 100 is a good average the next thing to note is that these numbers in the middle represent your fueling and obviously the bigger the number the more fuel you get but how does that work so these are basically a percentage or a multiplier against your required fuel you remember your acquired fuel that we loaded here from your basic uh your initial settings yeah so this is based on your parameters of your engine and your injectors that you have installed currently and what the required field represents is a theoretical value at 100 kpa and just so happens to be 70 degrees and um and 100 volumetric efficiency so that theoretical value of your engine um needs to be modified based on where it is in the table when it's not 100 kpa so typically around this line you're going to be having 100 kpa but as you increase in rpms even at 100 kpa you're going to need to increase the fueling and as you get lower obviously you need lower feeling and as you get above atmospheric pressure under boost you definitely need a lot more fueling and so this is because you're simply using more fuel you know you're you're making more power you've got more air in the engine and it has to compensate but also as you proceed up in load you are also changing the richness of what you're targeting so let's talk about that next all right so let's look at our next table and that is the afr table so the fr table is air fuel ratio table and these are target numbers which is used by the auto tune feature in tuner studio to determine whether it needs to pull fuel or add fuel to a given cell over here in our fuel table now this table is also used by the ego control and during normal driving so that it knows that if there's some difference from because of ambient conditions like temperature is a big one or you've just driven up into the mountains so your map values are different for a particular you know rpm that you would normally be at then it can add fuel or subtract fuel as needed to match these particular targets and generally that adding and subtracting process is a small percentage of this for any particular value in the table call it two percent so if you've got a well-tuned table you're not really using ego to change the feeling that much however when we're tuning boost we don't have a very good table yet so we're going to be using the analyze feature to change our field table based on these values so it's important to have these you know set up correctly and understandable so when you richen a mixture it will slow down the burn and cool it off adding the extra gasoline in there causes it to take energy away in from the heat that's latently in there and use it to vaporize that gasoline basically that the the liquid gasoline doesn't really burn what you need is the vapor gasoline and so that cools things down but then also as we increase our density where we're increasing the possibility of something exploding when we don't want it to that's called knock and so as density increases it's much more likely to have some sort of knock as you go up and by richening the mixture we're slowing down a burn and we're reducing the likelihood of knock so typically at the top end of your table you're wanting you're going to want to target in the 11th somewhere so let's get started first by taking a look at the afr ego control so egao is the exhaust oxygen control and it uses your wideband to determine whether you're running rich or you're running lean or you're running just right which is called stoichiometric 14.7 and a gasoline burning car so taking a look at this you can turn on and off when ego control will be happening and a typical thing to do is to limit it so that ego does not happen above a particular load value or kpa so at 90 we're going to turn it off and we're simply going to be relying on the table as it's written this is a good idea because you don't want the car to inadvertently be pulling fuel in the midst of a pull that you're doing at high load and therefore potentially disastrously leaning out the engine and causing some knock or pre-detonation something like that and causing engine damage ambient conditions don't really matter at higher levels of pressures and the reason for that is your intake air is going to be very hot anyway because it's just been compressed to a high degree by the turbo and hopefully it's gone through an intercooler you've got an inner cooler on the car and it cooled down to some degree but it's still going to be much higher than ambient and that that air is like almost like conditioned at that point it's super hot uh you know compared to normal and the whatever's happening outside your car doesn't really matter as much and so you want this to be under your full control you don't want anything weird happening you don't want the ecu going off on a tangent and suddenly subtracting a bunch of fuel when you're operating up here in this part of the table all right so we're turning off ego control while in boost so that we put it under our control and the next thing we can do is um set up the afr safety system so this is optional but it can be a good idea and basically what it means is when we turn this on it is going to look for a difference to the lean side of your afr versus what's actually being seen um in the car in terms of what your wideband is reading so here we're going to check above 100 so anything in boost as long as we're above 2500 rpm um we're going to let it stay lean for only half a second and then what it's gonna do is then what you know you're telling it what to do kill spark for uh half a second here and kill fuel until you lift so the cps or the throttle position sensor needs to be less than 20 so you've lifted your foot off the map needs to drop below boost and your rpms need to come down that's how it's set up by default which is fine you can you can basically tweak these settings this is an extra level of protection um when you're in boost all right so the next thing is we're going to go up here to boost and boost control settings and we don't care about our boost control itself and what this refers to is if you have an electronic boost controller and i recommend that if you do have one and or you have a manual boost controller which is basically something that you turn physically turn a dial or something like that i recommend disabling those taking them out so that you're operating on just the wastegate spring pressure and what that does is that's that's the wastegate is basically the um safest level to operate at especially when you're verifying your tune so do recommend that so we'll go over here to overboost production and by default it's turned on to both which is a good idea you can have fuel cut spark cut or both so we might as well do both and the maximum boost pressure in kpa that we're going to see here is set to 140. so i recommend going in stages when you're doing this type of tuning even though you're looking to maybe boost up to like 14 psi which would be equivalent to about 200 kpa you don't want to just immediately haul off and set that as your max you want to set something much lower so that you can verify that your fuel table over here is correct before you start getting into those higher pressures higher pressures is where there's more danger so you want to make sure your fuel table is correct and it's running returning the correct afr's back and it's not getting too lean as you go up now what hysteresis means is that when this occurs when the protection is turned on because it's gone to 140 or above then it will stay on until it's dropped 10 kpa so it'll go back down to 130 you can change this maybe you want it to you know go down a little bit slower um and uh you can change that to 15 or even 20 something like that to make sure that the boost has dropped down before it turns things back on now let's talk tables so tuner studio does the same thing in a way regardless of the table that you're looking at and that is so at the top levels you know in any of the edges basically what happens is whatever this last value is that's what's going to be maintained if you go past the top level so at this this table is tuned for up to 250 kpa so that means if you go above it then that's the fuel you're going to get so obviously you don't want to go above it because then you'll be probably giving less fuel than you should and it's the same out here typically you're not able to go above your rpm limit and so that's why you set your last row as the highest rpm possible this is quite a bit above a normal miata rpm limit rev limiter which is normally about oh 7 400 or something like that so what that means is that we're always going to be inside our table so just want to keep that in mind because if you go back to our afr table you'll notice it stops at 200 so these tables can be different from each other so it can be a good idea to change the tables to match each other just so that you don't get confused or you don't run into a part where you're off on one table you're out here somewhere up above the table as opposed to um you've got your you know you're the values that you want over here on this table so you want to get them to match if you're never going to be above 200 then you might as well set your fuel table to 200 and change these values so let's see how that works okay so to change our tables we can click over here and that opens up this new little screen with an extra column here an extra row here we're not going to really touch the rpm values at the bottom but we are going to change this so i like to go start at 20 and we can go by tens puts this at 100 and then i like to go by 15. and then we'll go at 205 for our top row and the reason for that is we don't plan to go above 200 but what that does is it keeps us on the chart like i mentioned so now that that's done what we're going to do is click this button to re-interpolate all these values so what it's going to do is because we've shifted some things up it's going to move these values around so the same it's going to be the same value for any given cell in the ones that we had before and then it's just going to move everything around so let's see what that looks like so this is when we're going to be able to start streak tuning and we can go over here and you see i've been modifying this ve table here on right here on the tuner tab so this is the analyze live tune if you have the free version of megasquirt what you'll be able to do is take the log and utilize that to do the same thing but if you have one of the paid versions then you get this in real time you can it will adjust these cell values in real time and show you all the changes that are made in the same way it'll show you this beginning value and you can see what the original value is that it was before it changed it so let's go over here and look at the settings here for how this changing actually happens so the first thing is the cell resistant change we've got some things very easy to very hard and what that means is that the as you drive it's going to count every time you hit a cell and so if the fuel value is wrong that in other words it does not match your afr and you say you're right here and it doesn't match your afr you're too rich say well it's going to pull some a little bit of fuel but it's only going to pull a very small amount based on the authority that it's allowed to and depending on what the cell resistance is it will require you to hit that cell multiple times and be wrong multiple times before it pulls much much of anything and so if you go to very easy you may only have to hit the cell once and it's actually going to start changing if you're on very hard you may have to hit the cell dozens of times before it starts changing so normal is somewhere in the middle it takes a few times hitting the cell and being incorrect before it'll start changing it and as you drive you can continue to drive it will start fixing you know all the different values so that they match your table now this is regardless of whether your ego control is on tuning street tuning with auto tune is different than ego control ego control can be on or it can be off during this process it really doesn't have an effect uh tuner studio and the mega squirt is smart enough to deal with all that stuff all right so let's start looking at what these values actually mean so let's assume that we are tuned down here and that this is the right value to match our afr table so as we progress up we are needing to add fuel for two reasons one is we're using we've got more pressure and we're making more power and two is we want to keep this richer this row needs to be richer than down here for safety reasons so you know if we look at our afr table you can see that we're at 13 on that on that uh row that used to be wide open throttle and now we're going to 12.6 so we're going to be adding a decent amount of fuel so let's just sanity check this is this correct so this is 15 more air we've just gone up 15 kpa so it's 15 more and so let's multiply this value let's get a calculator up and multiply this 113 times 1.15 15 percent it's 129. so we're pretty close but this is potentially a bit lean for this amount of extra fuel so just to be safe you can change this to 129 and we can see we can repeat this sort of down to make sure that this is looking okay and a trick to doing this is that if this is tuned we actually have hit the cell and stuff then we can see if this is correct and you can see that this is at 101 so this is sort of pretty good because um you can see this is 28 or 27 percent higher than this so the fuel is increasing so that's a little bit closer so what we want to do is we can make sure that all these things match in between here and that we're getting the right amount of fuel in this in this range so you can see here that it starts to richen up so at 3800 rpm maybe that was sort of the that at this point we're not really hitting the cell too often that once we start getting into into boost we're going to be more hitting it like around here as when we start getting up into that level and then because it's going to pass through these rpm levels very quickly so what you want to do is just verify using some of that just some basic math to see if the fuel is is acting like it is in these base maps i find that it usually is that it's going to be fairly rich all right so that's some sanity checking that we can do just before we even get in the car what about after we've done some pulls so again we've set up we've set our turned off our boost control uh so that we're at wastegate pressure we've set our cutoffs to a very low value say 140 is what we did and so basically it's going to reach a max of about here you know in here before it gets to cut off so we're going to do some pulls and it's going to come in here and it's going to it's going to change it so what i typically do for that is give it a little bit of extra help changing it to easy i verify my settings you know i don't want it to be doing anything under a certain rpm in fact i usually change this to 1500 or so because i've got my idle already tuned we don't want it to mess with that um and by the way it's it's a good idea to go go through and do some street tuning on this lower part of the map because like i said after you've added turbo especially these are for people who have just installed a turbo their thing was tuned just fine before the turbo but now it's got a turbo this used to be wide open throttle well 100 is no longer wide open throttle necessarily anymore this could be cruising you could be cruising and making a couple psi on a smaller turbo so therefore things may be a bit different it may be overly rich if you um if you leave it at that at that level because in cruising um with a little bit of extra psi you're really not putting that much load on the engine it just happens to be higher pressure it's getting more oxygen anyway so we can set some of our values here we can say what we want our um min fuel load to be the max amount of of um that i can be you can just leave that to just to give it latitude of what to do but importantly you want to change you want to set whether the cell value how much it can change given a particular session that you're doing or and the percentage value so if we look you know down here at one of these small ones say the amount the most of this can change by value is half according to this 50 50 um or it can change in value of up to 50 but it's only 40 so that means the the factor that's going to affect how much this can change is going to be the percentage one so the max that can change at any time plus or minus is going to be 20. whereas up here we actually could add 50 or subtract 50 because the half of this is 90. all right so what's going to be our approach we when we do a pull what's going to happen is these values are going to start changing and so an important thing to do is between sessions take a look at what happened so you'll see some changes in kind of a hump like this it'll you'll be going up and hitting like a particular thing as you go up in rpms now at the beginning because of our cutoffs we may actually not even get to these higher rev ranges because what's going to happen is it's going to get fuel cut before it even gets there so we're going to start kind of in the middle it's going to be hitting somewhere in here and you're going to have some changing of values so let's say this is all rich and this value ends up being 140. so you'll see this big pit in the table around there so you'll see that 140 pit will show up and it's visually very obvious so what you want to do is smooth that out you don't have to necessarily sit there and street tune trying to hit every single cell instead what you can do is interpolate these values and so what you do is you select what you want to interpolate to and you can choose one of these options so this goes horizontally this goes vertically and this moves it by a set factor and so if you've hit this cell and it's correct and you've hit a cell up here and that seems to be correct then in the middle is probably going to be you want a smooth transition between those two so you can select that and hit the horizontal smooth and it's going to make some changes in there it's going to smooth that out so it's going to be a smoother rise from this number to this number the same is true up and down so as we increase our values and we see that say um you know we get up to here you can see kind of a bigger jump in here that may be incorrect and so what you want to you may want to do is smooth up and down and you can do a whole set of smoothing and so what it's going to do is take each column and smooth it up and down based on the low value to the high value and what you're looking for is you're going to have a fairly smooth um graph here so in 3d mode it's it's pretty helpful to look at it because most engines you're not going to have too many little weird valleys like this like these little things that might be a specific area where the volume extra efficiency is not quite linear but you know this type of stuff is is kind of abnormal most of the time so as we get more runs and we get these values worked out down here then we can increase the amount of boost that we're allowed by going up and you know changing our cutoffs under boost settings or you know changing this or changing changing our afr cut off so you can keep the afr cut up that can work for the whole table but potentially you might want to make it less aggressive and we'll work our way up the table now this is a safe way of starting out with boost down here working our way up and getting to the top level so that you make sure you're always in the right ranges that you're looking to hit and you're not running into any kind of super lean conditions which is where you get your damage you

Channel: OGPedXing

Views: 19,431

Keywords: automotive, diy, miata, bmw, mx5, guide, howto, how to, car, project, mods, fix

Id: iQXvgi9BsE8

Length: 28min 32sec (1712 seconds)

Published: Tue Dec 22 2020