MoTeC M1 Software Tutorial: Engine Details
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Engine Details
12.03
| 00:00 | The first place to start with any M1 installation is the ‘Engine Details’ worksheet. |
| 00:05 | With the VE-based fuel model that the M1 ECU uses, it is critical for the ECU to know some key information about the particular engine it is controlling as well as the fuel you are using. |
| 00:18 | These parameters are used by the ECU for it’s air and fuel mass calculations. |
| 00:24 | We will talk through each of the parameters that we need to adjust now. |
| 00:29 | We start with the ‘Engine Run Threshold’, which describes the RPM at which the engine will transition from cranking to running. |
| 00:38 | This needs to be set correctly so that the ECU can apply the correct cranking compensation when the engine is being cranked, before switching to post start compensation when the engine is running. |
| 00:50 | By default this is set to 300 RPM, and this will probably suit most engines. |
| 00:57 | It’s important to select a realistic number here which is higher than the normal cranking engine RPM, but well below the normal idle speed. |
| 01:08 | ‘Engine Displacement’ is pretty self explanatory and defines the capacity of the engine in litres. |
| 01:15 | As this value is critical to the air mass calculation the ECU makes, it is important to make sure this is accurate. |
| 01:23 | When entering this value you should account for any modification made to the engine such as stroker crankshafts or if the engine has been fitted with oversized pistons. |
| 01:35 | The next parameter is ‘Engine Efficiency Mode’, which tells the M1 if we are using manifold pressure or throttle position for the load input. |
| 01:45 | For most typical engines running a single throttle body and plenum arrangement, the correct setting here will be ‘Manifold Air Density’. |
| 01:55 | If you are tuning an engine running multi-throttle bodies and using throttle position for the load input, you would select ‘Ambient Air Density’ instead. |
| 02:05 | This allows the engine efficiency to be scaled or adjusted based on ambient air density or barometric air pressure. |
| 02:13 | If you want to use ambient air density, the ECU will assume that you have an ambient air pressure or barometric air pressure sensor fitted and correctly configured. |
| 02:25 | If you haven’t, it’s essential to make sure you have correctly set the default value for this parameter. |
| 02:32 | ‘Engine Cylinders’ is again quite self explanatory and this is used as part of the engine capacity calculation to let the engine know what the capacity of each cylinder is. |
| 02:44 | ‘Engine Charge Cooling Gain’ defines how much the intake charge is cooled by the fuel being injected. |
| 02:51 | When fuel is injected, it will absorb heat from the intake charge as it goes through a phase change from liquid to vapour. |
| 02:58 | This is defined by the fuel’s latent heat of evaporation. |
| 03:03 | The resultant change in intake charge temperature will affect the intake charge density and hence this will also affect the accuracy of the fuel modelling. |
| 03:13 | or this reason it is important to set this parameter accurately. |
| 03:18 | Changing this parameter will affect the efficiency calibration so its important to calibrate this before you tune the actual efficiency table. |
| 03:27 | We will look at how to do this a little further on in the course. |
| 03:32 | The next setting we have is ‘Engine Load Normalised’, which describes what parameter the ECU is going to use as the load axis for the ignition table. |
| 03:42 | We have three selections here which are ‘Normal’, ‘Inlet Manifold Pressure’, and ‘Throttle Position’. |
| 03:50 | Normal mode is intended to accurately describe the percentage of cylinder fill at any point in the table. |
| 03:58 | This mode references the engine’s volumetric efficiency value from the Engine Efficiency table at the particular point the engine is operating as well as inlet manifold temperature. |
| 04:11 | For example if the manifold pressure is 100 kPa, the Engine Efficiency is 90% and the inlet manifold temperature is 20 degrees, the Engine Load Normalised value would be 90%. |
| 04:27 | If the manifold pressure is 200 kPa and the engine efficiency is 100%, the Engine Load Normalised value would be 200%. |
| 04:39 | It’s important to understand that if you use this mode, the load input for the ignition table will change if you alter the numbers in the Engine Efficiency table. |
| 04:51 | ‘Inlet Manifold Pressure’ will give you a load axis for the ignition table that you would be familiar with seeing in a traditional ECU such as MoTeC’s 100 series range. |
| 05:02 | Here the load value for the ignition table is simply the inlet manifold pressure. |
| 05:08 | If you are tuning an engine using multi throttle bodies, ‘Throttle Position’ will be your best choice. |
| 05:15 | ‘Engine Load Average Time Constant’ defines the time frame that is used to average the engine load. |
| 05:22 | We will look at how we can use this feature in more detail a little later, but in essence it is used to define how hard the engine is being used. |
| 05:32 | We can use the resulting Engine Load Average value to perform compensations to the fuel or ignition to help safeguard the engine. |
| 05:41 | The value here is measured in seconds and is the time period the ECU will use to average the engine load. |
| 05:48 | Longer periods will result in a more stable and consistent Engine Load Average value, while shorter time periods will allow a more erratic change. |
| 05:59 | This number needs to be set according to the type of use the engine is designed for as well as how you want to use the result of the average engine load calculation. |
| 06:11 | Next we have the ‘Fuel Stoichiometric Ratio’ which is pretty straight forward. |
| 06:17 | This needs to be set correctly to suit whatever fuel you are running the engine on. |
| 06:22 | This is used as part of the fuel equation to define what mass of fuel needs to be delivered to achieve a target mixture aim value. |
| 06:31 | A list of stoichiometric AFR values for most common fuels is included in the help file. |
| 06:39 | ‘Fuel Density Reference’ and ‘Fuel Density Temperature Coefficient’ define the mass of fuel based on fuel volume as well as how the density will alter with temperature. |
| 06:50 | Suitable values for many common fuels are included in the help, and if you are running on a specially blended race fuel, typically this information will be available from the supplier. |
| 07:03 | If you have a fuel temperature sensor fitted, this will be used in conjunction with these two parameters so that the ECU knows the actual fuel density. |
| 07:12 | Again these parameters are an important part of the fuel equation and need to be correctly set. |
| 07:20 | Next we have ‘Fuel Injector Location’ which can be set to ‘After Throttle’ or ‘Before Throttle’. |
| 07:28 | This parameter tells the ECU if the injector will be exposed to inlet manifold vacuum as it would be if it was fitted in the usual post throttle body location. |
| 07:38 | This affects the differential pressure across the injector, which is the difference between fuel pressure and manifold pressure. |
| 07:46 | This in turn affects the fuel flow through the injector. |
| 07:51 | ‘Inlet Manifold Pressure mode’ tells the ECU how the inlet manifold pressure will be determined. |
| 07:58 | Usually we would expect this to come from the inlet manifold pressure sensor and we can choose this option if we wish by selecting ‘Sensor’. |
| 08:08 | In this case, if the sensor goes into fault, the ECU will use the default value entered into the sensor configuration. |
| 08:16 | ‘Automatic’ mode will use the value from the sensor unless the sensor is deemed to be in error. |
| 08:23 | If the sensor is in error, the ECU will revert to the value in the ‘Inlet Manifold Pressure Estimate’ table which defines the estimated inlet manifold pressure relative to RPM and throttle position. |
| 08:38 | Provided the ‘Inlet Manifold Pressure Estimate’ table is correctly filled in which we will look at shortly, this offers a better backup solution if the MAP sensor does become faulty. |
| 08:50 | If we are tuning an engine using throttle position as the load input, we can choose ‘Estimate’ and this will use the ‘Inlet Manifold Pressure Estimate’ table as the load input. |
| 09:01 | We can now set up the Inlet Pressure Estimate Table to convert the throttle position input into a manifold pressure estimate which will then become the reference point in the Engine Efficiency table. |
| 09:15 | In it’s simplest form, we can go into the table axis and turn the Inlet manifold Pressure Estimate table into a 2D table with the engine speed axis turned off. |
| 09:27 | We can then create a linear relationship between throttle position and manifold pressure where 100% TPS equals 100 kPa, and 0% TPS equals 0 kPa. This won’t be entirely realistic, but the load axis will now respond the same as what you would have been used to in MoTeC’s older hundred series ECUs. |
| 09:52 | The last parameter we have in this particular list is the ‘Throttle Area’ table which is only used in drive by wire applications. |
| 10:02 | By their nature, the flow through a throttle body is very non linear in relation to throttle opening. |
| 10:08 | This table describes the throttle area as a function of throttle opening so that when we move the throttle pedal, we are actually requesting a specific throttle area. |
| 10:18 | This tends to linearise the throttle curve and makes the engine response more linear in relation to throttle input. |
| 10:26 | The last aspect we need to configure is the cylinder firing angle and bank allocation. |
| 10:33 | With the MoTeC M1 ECU, each injector and ignition output is wired to its respective cylinder. |
| 10:40 | By this I mean that injector one is wired to cylinder one and injector two is wired to cylinder two etc. |
| 10:48 | This table defines the firing order and we need to enter the crankshaft angle that each cylinder will fire at. |
| 10:56 | Cylinder one is always assumed to fire at zero degrees. |
| 11:00 | If your engine is a V-configuration, you will also need to allocate a bank number to each cylinder. |
| 11:07 | This is important for bank to bank compensations for fuel as well as knock control. |
| 11:13 | If you have an inline engine, usually all the cylinders will be set to ‘Bank 1’. |
| 11:19 | Exceptions do exist though such as where an inline six cylinder engine uses two groups of three cylinders for the exhaust manifold integration. |
| 11:29 | In this instance we would want to assign each group of three cylinders to a separate bank. |
| 11:35 | This will be beneficial for aspects such as close loop fuel control where a separate lambda sensor can be assigned to each bank of three cylinders. |
| 11:45 | Also when we look at assigning knock sensors for knock control, we can’t reference the second knock sensor on the same bank. |
| 11:55 | This will now have the Engine Details worksheet complete and we can move on to set up the Ref/Sync inputs. |
