Link G4 Plus Software Tutorial: Advanced Limits
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Advanced Limits
04.02
| 00:00 | - While the normal limiting functions will be adequate for most situations, advanced limiting allows more control and the potential for smoother limiting. |
| 00:09 | Let's turn on advanced limiting and have a look at settings. |
| 00:14 | Advanced limiting mode is available for any of the ECU limiting functions including MAP, RPM and GP limits. |
| 00:21 | To explain the parameters, we will look at the RPM limit but the parameters are the same for any of the other limit functions. |
| 00:30 | We can access the advanced limit setup from the RPM limit menu in the ECU settings menu. |
| 00:37 | Once we have the RPM limit menu on the screen, we need to run the advanced mode to on to see the other parameters. |
| 00:44 | Hard limit defines what the ECU will do if the hard limit activation point is reached. |
| 00:50 | We can turn off the hard limit all together or use 100% fuel cut, 100% ignition cut or both fuel and ignition together. |
| 01:01 | Cut effect controls the sequence in which the cylinders are cut. |
| 01:05 | Adaptive, which is the default option, randomises the cut pattern so that no individual cylinder is cut too many consecutive times. |
| 01:13 | Constant on the other hand, applies a fixed sequence depending on the percentage of cut applied. |
| 01:19 | Limit control range defines the RPM range over which the cut will become active. |
| 01:25 | It's important to understand that this happens before the actual RPM limit. |
| 01:30 | For example if your rev limit is set to 7000, and the control range is 200, then the rev limit will begin at 6800 RPM. |
| 01:40 | A range of 200 is a typical setting. |
| 01:44 | The hard limit activation defines how far past the RPM limit setting the hard cut will be activated. |
| 01:50 | A typical value would be 200 RPM. |
| 01:54 | Note that this will allow the engine to exceed the rev limit by up to 200 RPM before the hard cut is activated. |
| 02:02 | End cut, specifies the percentage of cut that will be applied at the end of the control range. |
| 02:08 | A typical value will be 90%. |
| 02:12 | Start cut, TP 100 specifies the amount of cut that will be applied when entering the beginning of the control range at full throttle. |
| 02:20 | Since we're entering the limit range with more engine power due to the throttle opening, a large cut is required. |
| 02:27 | A value of 60% is typical. |
| 02:30 | Start cut TP low specifies the amount of cut that will be applied at the start of the control range when the throttle is below the TP low threshold. |
| 02:40 | Since the engine power is lower, less cut is required. |
| 02:44 | A typical value would be 30%. |
| 02:48 | TP low defines the percentage of throttle opening below which the ECU will use the TP low start cut value. |
| 02:55 | Exit decay rate specifies how quickly the cut is reduced after exiting the control range. |
| 03:01 | The exit decay rate is a percentage of cut removed per 20 milliseconds. |
| 03:06 | Larger numbers will remove the cut faster. |
| 03:11 | Limit ignition trim will retard the ignition timing when the RPM is within the control range. |
| 03:17 | This can help smooth the limiting. |
| 03:19 | The help file contains a handy diagram that explains graphically how the different parameters of the advanced limiting function work together. |
| 03:27 | This can make it easier to understand the advanced limiting function. |
| 03:31 | You can find it by searching advanced limiting in the help file. |
| 03:35 | When tuning the RPM limit parameters, the aim is to provide stable limiting without overshooting the limit range. |
| 03:43 | When the limiting is stable, the percentage cut parameter will also be stable. |
| 03:47 | This parameter can be logged to check how well the limiter is functioning. |
| 03:52 | If the engine tends to overshoot the RPM limit, raise the start cut values. |
