An external wideband lambda may be wired to the ECU for datalogging, lean protection and closed loop operation.
Wideband Input Source
The Input Source selects what ECU input is connected to the wideband analog output.
| • | o2 sensor is the stock o2 sensor input pin (pin D14) |
| • | ELD is the LED input (pin D10) |
| • | EGRL is the EGRL input (pin D12) |
| • | Analog input 2 (pin B6) |
Note that if the ELD input (D10) is used then R136 and R138 (US ECUs) may need to be removed.
Voltage offset shifts the voltage/lambda conversion by the specified voltage in order to compensate for slight differences in voltage between the ECU and lambda meter. Note that any non zero voltage offset indicates a ground different between the wideband and ECU, which will affect accuracy. The wideband should always be grounded to the same point as the ECU (the thermostat housing).
Voltage / Lambda Conversion Table
The voltage/lambda conversion table is specific to each lambda meter. Details can usually be found in the lambda meter instruction manual. Note that the lambda unit (lambda or air/fuel) is specified in the Settings/General window.
Common voltage/lambda conversions:
PLX & most AEM
Voltage |
Air/Fuel |
0V |
10:1 |
5V |
20:1 |
Innovative
Voltage |
Air/Fuel |
1V |
10:1 |
2V |
20:1 |
Techedge
Voltage |
Air/Fuel |
0V |
9:1 |
5V |
19:1 |
Target lambda
The target lambda tables are used when running closed loop using the wideband input (with a target lambda). Out of the two target tables, the most rich value is used. eg if the water temperature indicates a target lambda of 13.5:1 and the engine load suggests 14.7:1, then the richest value (13.5:1) will be used.
Running Closed Loop under High Load
It is possible to run in closed loop under high load so that an optimal air/fuel is achieved. To do this you should:
| • | Select Closed loop - wideband input (target lambda) in Closed Loop Settings. |
| • | Set the Maximum MAP for closed loop higher than your highest expected boost level. |
| • | Set the Maximum engine speed. |
| • | Set the Closed Loop Max TPS to 100% |
| • | Limit the short term fuel trim to around -10% / +10% |
| • | Make sure the voltage / lambda conversion table is correct. |
| • | Set the target lambda tables to the desired air/fuel under boost. |
| • | Make sure the wideband is in good working order and reading accurately. |
| • | You may also have to alter the short term trim rate of change tables. |
Wideband Lambda Changes For V1.3
In version prior to V1.3.0 the wideband lambda settings were retained as a SManager configuration option, and the datalogged wideband voltage input was converted in SManager either when datalogging or when a datalog was loaded. From V1.3.0 onwards the wideband lambda settings are retained in the ECU calibration, and the datalogged wideband voltage input is converted in the ECU.
These changes have the following consequences:
| • | Wideband lambda settings has been removed from the Settings window. |
| • | Datalogged lambda values cannot be changed by changing the calibration wideband lambda parameters. |
| • | Datalogs make with versions of SManager prior to V1.3.0 need to nominate the wideband conversion used (see below). |
| • | Loading datalogs made with SManager V1.3.0 onwards do not require the |
If a datalog from a previous version of SManager is loaded, the following conversion window is shown:
Once the datalog is re-saved the lambda information will be updated in the datalog, and the conversion does not need to be re-performed.
Closed Loop Minimum Temperature
The ECU will run in open loop when the coolant temperature is low.
There are three different tables which determine when the ECU will run in closed loop, indexed by vehicle speed. 'Slow' is below approximately 20 kph, 'fast' is over 80 kph and 'medium' is in between these two speeds.