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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.