Link G4 Plus Software Tutorial: Closed Loop Lambda Control
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Closed Loop Lambda Control
03.10
| 00:00 | - The closed loop lambda function allows the G4+ to take input from a lambda sensor and automatically make adjustments to the fuel delivery to meet a target. |
| 00:09 | This can help keep your air/fuel ratio more consistent across varying atmospheric conditions, improving fuel economy and reducing emissions. |
| 00:18 | The closed loop lambda function can be accessed by opening the ECU settings menu and clicking on fuel and then closed loop lambda. |
| 00:26 | By default, this function is disabled so you will need to set it up to suit. |
| 00:31 | First we need to select the lambda mode and this will depend on the type of sensor you're using. |
| 00:36 | Stoich narrowband will suit narrowband sensors that are only accurate around the stoichiometric air/fuel ratio while stoich wideband will work with wideband sensor controllers. |
| 00:48 | If you're using a narrowband sensor, the closed loop lambda control can only correct the AFR to stoichiometric which is only useful for cruise and light load situations. |
| 00:58 | A wideband sensor on the other hand will allow full control and the ECU will attempt to match the values entered into the AFR lambda target table. |
| 01:07 | We will look at setting up the wideband mode so we can select this option. |
| 01:12 | We now have a number of parameters that need to be configured. |
| 01:15 | First we have ECT lockout which prevents the ECU going into lambda control below a certain temperature. |
| 01:22 | This ensures the closed loop control isn't active during warmup enrichment. |
| 01:27 | The next option is the timer lockout. |
| 01:29 | This prevents closed loop control for a certain length of time after startup. |
| 01:34 | This gives the sensor time to start working and gives the engine time for any post start enrichment to decay. |
| 01:40 | We then have some parameters that allow us to define when the closed loop lambda control will be active. |
| 01:45 | These are RPM high, RPM low and MAP lockout. |
| 01:50 | The lambda control will only be active when the engine is operating between the RPM high and low lockouts and below the MAP lockout. |
| 01:57 | Normally closed loop lambda control is used to control the AFR during cruise and light load so these parameters need to be adjusted to suit your requirements. |
| 02:07 | Next we have the fuel trim limit which limits the amount of control the ECU has over the fuel trim. |
| 02:13 | Closed loop lambda control is not a substitute for proper tuning and the ECU should not need to make large changes. |
| 02:20 | Lastly we have the gain control which defines how aggressively the ECU will chase the target. |
| 02:27 | This needs to be adjusted until the ECU matches our target quickly without overshooting and oscillating wildly. |
| 02:33 | You can watch the closed loop control in the run time values screen under fuel trims. |
| 02:37 | This can help you tune the gain but normally a value of two to three works well. |
| 02:44 | Since we are using a wideband sensor, it's important to makes sure that the AFR lambda target table is set to what we want the engine to run. |
| 02:52 | This is the table the ECU will reference to make changes so it needs to be set properly. |
| 02:57 | If you are using a narrowband sensor, it's important to adjust the lockouts to ensure that closed loop control will only be active at idle and cruise. |
