WinOLS Mastery: Map Identification & Editing: ECU Logic Flow - EDC17
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ECU Logic Flow - EDC17
09.36
| 00:00 | - The next controller we're going to cover is Bosch's diesel engine ECU which has the acronym EDC and this stands for electronic diesel control. |
| 00:08 | This is a family of ECUs which started back in the mid 80s and just like Bosch's gasoline controller range, there's a variety of different ECUs within the family that incorporate different features to suit a specific manufacturer and application. |
| 00:23 | We'll again be looking at the EDC range from a high level, focusing on the general operating strategy and which tables you'll need to locate and define in order to be able to tune a basic stage one diesel vehicle, fitted with a Bosch EDC controller. |
| 00:37 | There is an important key difference in the control strategy depending on the specific generation of EDC controller you're working with as the EDC15 and earlier are based on injection quantity while the EDC16 and later switched to a torque model instead. |
| 00:53 | This module however will give a high level understanding that's applicable to the entire family of controllers before getting more specific as usual with our worked examples. |
| 01:04 | Let's start with the driver requested torque or driver's wish table. |
| 01:08 | Unlike the ME and MED controller we've just covered in the previous module, Bosch's EDC controller doesn't use nice short simple acronyms that roll off the tongue easily. |
| 01:18 | For this reason, instead of trying to say these table names out loud, what we're going to do is list these on screen so you know exactly what I'm talking about. |
| 01:27 | For example, this is how Bosch name this particular table and there will be typically multiple maps. |
| 01:35 | In some cases one for each gear or for different drive modes. |
| 01:38 | These tables are 3D with relative pedal position on the X axis, engine RPM on the Y axis and the Z axis is the torque request. |
| 01:47 | With an EDC controller, the torque request is in newton metres rather than the relative torque value that we learned about in the last module. |
| 01:54 | The RPM axis is usually going to be a value in the range of zero to 8192 and this can be scaled using a value of 81.92. |
| 02:05 | The engine RPM value is a raw value in the earlier controllers, however in the EDC17 you'll need to divide by two or 0.2 depending on the specific version of the controller. |
| 02:17 | However the original numbers will guide you on the required scaling. |
| 02:21 | Lastly, the torque value will need to be divided by a factor of 10 to scale this correctly. |
| 02:26 | Once a torque request value is established, we move onto the torque limitation. |
| 02:31 | Depending on the variant of EDC controller, this can be done a few different ways. |
| 02:35 | Basic early EDC controllers will have a limited number of 16x1 or 33x1 tables which will have RPM as the X axis and the Z axis will be the torque limit value in newton metres. |
| 02:48 | Later controllers will use a table called this in EDC16 or this in EDC17. |
| 02:56 | These are 4x24 tables with RPM on the X axis, barometric air pressure on the Y axis and torque on the Z axis. |
| 03:05 | You may also find multiple torque limit tables, one for each gear. |
| 03:09 | There will also be, in some cases, an individual single value torque limit value referred to as this, which can be easy to miss and frustrating during the tuning process. |
| 03:20 | On most auto equipped vehicles, there will be one of these single value torque limits for every gear. |
| 03:25 | While it's not usually a big concern on some controllers there may also be a specific torque and RPM limitation for reverse gear. |
| 03:32 | The Volkswagen Amarok includes this, just as an example. |
| 03:35 | Once we have a final torque value, this becomes an input to a series of torque to fuel mass tables, usually referred to as NM conversion tables. |
| 03:45 | This converts the requested torque into an injection quantity value that the injectors need to deliver in units of milligrams per cycle. |
| 03:53 | The tables will be referred to like this and will be RPM on the Y axis with torque on the X axis. |
| 04:00 | Again, there will be multiple tables in most instances. |
| 04:04 | The injection quantity value output from the conversion table may then be limited by the smoke limitation table. |
| 04:10 | The axis for this table will either be lambda and air mass or maximum injector quantity and air mass which are really just two ways to achieve the same outcome. |
| 04:19 | At this point we'll have the final calculated injection quantity referred to as fuel mean amount of FMA for short. |
| 04:27 | This will also pass through several limitation tables relating to intake air temperature, engine coolant temperature, oil temperature for both the engine and gearbox in some cases, exhaust gas temperature and even actual road speed. |
| 04:41 | These tables will usually use a Z axis value of 8192 in an area where no change is required and if we divide this number by 8192 and add a couple of decimal places, you end up with a mutliplier. |
| 04:56 | For instance, a value of 8192 in hexadecimal, divided by 8192 equals 1.00. |
| 05:05 | If you apply the same math to a value of say 7000, this results in a value of 0.85. |
| 05:11 | This is then applied as a factor to the FMA, resulting in a reduction of fuel of 15% as the thermal load increases so the Z values reduce in order to reduce the final fuel value and safeguard the engine. |
| 05:26 | Once any limitations have been applied, the FMA value will pass onto the start of injection tables which are referred to like this. |
| 05:32 | There can be more than 40 variations on these tables for aspects such as cold start, regen, high temp and more. |
| 05:40 | These are one of the only tables where the Z value can't be calculated using logical or binary numbers. |
| 05:46 | For Volkswagen/Audi Group vehicles, you'll need to divide the raw values by 42.6 and all others as far as we've found use a value of 31. |
| 05:55 | Now we can move onto the inlet charge which is calculated as an absolute value in most cases. |
| 06:00 | This runs in tandem with the FMA calculation. |
| 06:04 | The tables are referred to like this and in some instances there will be minimum and maximum tables in which case typically only the maximum values need to be adjusted. |
| 06:13 | In most instances, the table size will be 16 x 16 but this can vary slightly among different controllers. |
| 06:20 | The Y axis will be RPM and the X axis is requested injection quantity. |
| 06:24 | The Z axis of course is charge pressure which is expressed in absolute millibars. |
| 06:30 | Next we'll have the limitation tables, usually including barometric pressure as well as a single value charge limit. |
| 06:36 | There'll also be a correction table for air density which is usually calculated from a MAF table or sensor calculation. |
| 06:43 | This will advice the ECU at lower intake air temperature that less charge pressure is required due to the increased air density at these lower temperatures. |
| 06:52 | Once the ECU has calculated a final charge pressure target, this will then use the base VNT set point tables referred to like this in order to achieve the target pressure. |
| 07:02 | There are both minimum and maximum tables for VNT set point and these will be a 16 x 16 table. |
| 07:08 | The Y axis is RPM while the X axis is injection quantity. |
| 07:12 | The Z axis will be a value from 0 to 8192 and by dividing this raw value by 81.92, you'll get a duty cycle with a base set point control. |
| 07:24 | There are additonal boost pressure limits that will affect the final charge pressure. |
| 07:29 | The specifics of which will vary depending on the controller. |
| 07:32 | Normally boost will be limited based on barometric pressure in a 3D table form but there will also be a single value limiter as well. |
| 07:41 | Some controllers also include a compaction ratio or pressure ratio limitation. |
| 07:45 | EDC17 also include compressor speed tables that limit charge pressure if the calculated turbo speed is exceeded. |
| 07:54 | Next we move onto rail pressure which is typically a 16 x 16 table, known as this. |
| 07:59 | This table uses engine speed as the Y axis and the X axis is injection quantity. |
| 08:06 | The Z axis of course is target rail pressure, this time in hectopascals. |
| 08:11 | You can however divide this value by a factor of 10, representing rail pressure in bar instead if you prefer. |
| 08:18 | Rail pressure limitation is handled with a combination of tables and single value limiters. |
| 08:23 | Lastly we also have injection on timetables, known as this. |
| 08:28 | These are the largest and easiest maps to find and represent the amount of time the injector needs to be open for in order to provide the requested fuel quantity. |
| 08:37 | The Y axis is requested injection quantity, the X axis is rail pressure and the Z value is injector on time. |
| 08:44 | As a rule of thumb, you would start by checking the driver requested torque value and comparing this to the actual torque value seen in the log of the standard vehicle. |
| 08:53 | Most of the time, the requested torque is higher than the delivered torque as a result of the limitation tables. |
| 08:59 | Just simply bringing these limitation tables up to match the driver requested torque will usually result in exactly that, more torque. |
| 09:07 | If more fuel is required, the NM conversion table is the place to do this, not the on time tables. |
| 09:14 | Increasing the fuel value must be done while also considering the smoke limitation. |
| 09:18 | These tables will need adjusting to allow the ECU logic to increase the fuel mass. |
| 09:24 | Increasing the charge pressure slightly will also help with fuel burn and torque. |
| 09:29 | Sometimes gains can be found in very slight changes to the rail pressure tables. |
