MoTeC M1 Software Tutorial: Engine Speed Limits
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Engine Speed Limits
10.27
| 00:00 | The third worksheet we need to deal with is the Engine Speed Limits worksheet. |
| 00:05 | We have already briefly looked at a couple of these parameters that are repeated in the Ref/Sync worksheet, but now we will look at setting up the Engine Speed Limits in a little more detail. |
| 00:15 | The M1 ECU offers a range of different speed limiters depending on the operation of the engine and what we want to achieve. |
| 00:23 | We can see here on the left hand side of the worksheet we have the ‘Limit Tables’ which describe the different limits. |
| 00:30 | In this package we have a limit table for ‘Coolant Temperature’, ‘Average Load’, as well as the ‘Engine Speed Limit Maximum’. |
| 00:40 | The ECU will look at all of these tables and apply the limit that is lowest under any particular operating condition. |
| 00:47 | If we want to use the M1 ECU like a more conventional ECU, this means that we can set the engine speed limit solely off the Engine Speed Limit Maximum table. |
| 00:57 | Provided the other limit tables are set to a higher value, they will never become active. |
| 01:04 | If we want to reduce the engine speed limit though if the engine temperature becomes too hot, we can do this with the “Coolant Temperature Engine Speed limit’ table. Let’s have a look at how that would function now. |
| 01:18 | When you first start setting up a blank M1 calibration, all the engine speed limits are just a single number and we can see this here if we click on the Coolant Temperature Engine Speed Limit. |
| 01:30 | By default it’s set to 5500 RPM. |
| 01:34 | Let’s say that we want to reduce the engine speed limit to 5000 RPM if the coolant temperature gets above 100 degrees C. |
| 01:43 | To do this we are going to need to set up a 2D table and we can do this by pressing the ‘A’ key, or right clicking and selecting ‘Setup Axis’. |
| 01:54 | Now we want to tick the ‘Enable Axis’ button to turn on the Coolant Temperature axis. |
| 02:00 | I’ll just set up a basic table here with a few points in it that we can use to set our desired engine speed limit. |
| 02:08 | Don’t worry too much about the axis setup right now as we will cover this in detail in a later module. |
| 02:15 | Now that I’ve got the coolant temperature axis configured, I’m going to set the minimum RPM to 5000 above 110 degrees C. |
| 02:25 | What this means is that in this case the M1 will start using the Coolant Temperature Engine Speed Limit once the coolant temperature exceeds 100 degrees C as this will now become the lowest requested limit. |
| 02:40 | An important note here is that just like any table in the M1, the engine speed limit value interpolates between cells. |
| 02:48 | This means that in our example, the engine speed limit will actually start reducing as we exceed 100 degrees C and from one hundred degrees through to one hundred and ten degrees C, the limit will smoothly decrease from 5500 to 5000 RPM. |
| 03:07 | The ‘Engine Load Average’ table allows us to adjust the desired engine speed limit based on the average load, or how hard the engine is being operated. |
| 03:18 | Again in the default package this is a single value. |
| 03:22 | If you want to use this function you will need to enable the axis and configure it to suit. |
| 03:28 | The parameter we will be most interested in though is the main engine speed limit and this is configured through the ‘Engine Speed Limit Maximum’ table. |
| 03:37 | This is the RPM limit parameter that users of the older hundred series MoTeC ECUs would be familiar with. |
| 03:45 | When we click on this you can see that we have the two values, listed as ‘A’ and ‘B’ This can be used to adjust the engine speed limit based on a driver position switch for example. |
| 03:57 | One important aspect to remember is that the M1 ECU will always use the lowest engine speed limit being requested. |
| 04:05 | Particularly when you are first configuring a new ECU, there is a pretty good chance that you will want to lift the engine speed limit from the default 5500 RPM. |
| 04:16 | To do this, you need to adjust each table to your desired speed limit value. |
| 04:23 | On the right hand side of the worksheet we have an ‘Engine Limit State’ display which will tell you where the ECU is currently getting its engine speed limit from. |
| 04:33 | You can see here that the state is displaying ‘Maximum’ as this is our lowest requested engine speed limit. |
| 04:41 | This state is displayed here below as well in the ‘Engine Speed Limit Channels’ along with the actual engine speed limit value here. |
| 04:50 | If we change the value of the ‘Coolant Temperature Engine Speed Limit’ to a value below our maximum, we will see that the state changes. Let’s do that now by setting the entire table to a value of 4500 RPM. |
| 05:04 | We can do this by clicking on the table, highlighting all the values and typing in 4500 and pressing enter. |
| 05:13 | Instantly you can see that the ‘Engine Speed limit State’ changes to ‘Coolant Temperature’, and the new engine speed limit is displayed below in the channels list. |
| 05:24 | This is a really fast and easy way of figuring out what is requesting a limit at any particular time. |
| 05:31 | Next we are going to look at the Warning Limit Parameters displayed here in the left bottom corner of the worksheet. |
| 05:37 | These are a range of optional warnings we can use to induce a lower engine speed limit if we want see the need. |
| 05:44 | These warnings work in conjunction with the configuration for each of the relevant sensors and for the warning system to function, you will need to set them up correctly. |
| 05:53 | We would normally do this when we configure the sensor, but let’s have a look at an example now. |
| 06:00 | Let’s say we want to enable an engine speed limit of 4500 RPM if the engine oil temperature exceeds 150 degrees C. |
| 06:09 | We can do this by moving through the list until we find the ‘Engine Oil Temperature Warning Engine Speed Limit’ parameter, and select our desired speed limit of 4500 RPM. |
| 06:21 | You can see we have another parameter below this that allows us to set a delay. |
| 06:26 | If this is left set to zero, the limit will become active as soon as the temperature exceeds our limit. |
| 06:32 | Now we need to complete the configuration of the warning and there are a couple of ways to do it. |
| 06:38 | Personally I use the all calibrate worksheet and then just type ‘Oil Temperature Warning’ into the search bar. |
| 06:46 | To use any of the warnings, we first need to enable the ‘Warning Mode’ for the particular function we are interested in. |
| 06:54 | Once the warning mode is enabled, there are two options for controlling the warning. |
| 06:58 | These are the ‘Warning Mode Sensor Diagnostic’ which will bring on the warning if the sensor input exceeds the diagnostic voltage limits and is deemed to be faulty, we also have ‘Warning’ which will bring on the warning if the measured value exceeds our minimum or maximum values. |
| 07:17 | You can use just one of the warning modes or both together if you prefer. |
| 07:23 | We can now select a minimum and maximum for our oil temperature warning range. |
| 07:28 | It’s important to set both sensibly, as the engine speed will be limited if the temperature is below the minimum, or above the maximum. |
| 07:36 | I’ll leave the minimum set to zero and adjust the maximum to 150 degrees C. |
| 07:42 | The hysteresis defines how much the temperature needs to move to turn the warning back off after its been triggered. |
| 07:50 | If we set this to 2 degrees for example, the warning will trigger at 150 degrees, but then the temperature needs to drop to 148 degrees before it is turned back off. |
| 08:01 | This is used to stop a warning switching on and off repeatedly when the measured value is sitting at the minimum or maximum value. |
| 08:10 | Next we have the delay and limit values, which are simply repeated from the Engine Speed Limits worksheet. |
| 08:16 | We can set up as many or as few of these limits as we see fit to adequately protect the engine under a variety of conditions. |
| 08:25 | The last parameters we are going to look at are the ‘Margin’ and ‘Range’ parameters which define how the engine speed limit will function. |
| 08:34 | Basically these parameters define the RPM range over which the ignition cut and fuel cut will become active. |
| 08:41 | It’s worth mentioning that in the M1 there is no specific adjustment for setting a fuel cut limiter or an ignition cut limiter, and how the limiter works is defined here. |
| 08:54 | Let’s look first at the ‘Engine Speed Limit Ignition Range’ which by default is set to 200 RPM. |
| 09:01 | What this means is that when we reach our RPM limit, the ECU will begin ignition cutting and slowly ramp this cut up to 100% over 200 RPM. |
| 09:12 | So if our engine speed limit was set to 5000 rpm, the ignition cut would begin at 5000 RPM and reach 100% CUT by 5200 RPM. |
| 09:22 | This provides a control range for the engine speed limiting which offers a smoother limit. |
| 09:28 | If you set this value to zero, the ECU would provide a 100% ignition cut at the RPM limit which would give a very aggressive hard cut. |
| 09:38 | We also have the ability to use a fuel cut to supplement the ignition cut and this operation is defined by the ‘Fuel Margin’ parameter. |
| 09:48 | In the GPA and GPR packages, the ECU predominantly relies on ignition cutting and you can see that the margin by default is set to 10,000 rpm so it’s effectively disabled. |
| 10:00 | As with the ignition range, the ‘Fuel Margin’ defines how far above the engine speed limit, the fuel cut will occur. |
| 10:08 | In the GPA and GPR package, the fuel cut rises instantly to 100% with no control range. |
| 10:15 | Adjusting these parameters will effect how smooth or how aggressive the engine speed limit is. |
| 10:21 | We are now ready to move on to setting up our sensors. |
