Unit configuration

When configuring units, there may be times where you are unable to select other existing scaled units. This is because there are no available conversions, so you need to select a different base unit.

An example of this issue is the Air-to-fuel Ratio (AFR/Lambda). For some ECUs, Lambda readings are specified in the unitless quantity ‘AFR’. This has no real meaning or relationship to other AFR units, so the base unit needs to be changed to one that is quantified and convertible. To resolve this, select the base unit that matches the current fuel type.

Some of GEMS ECUs provide a user Enumeration/Option List ‘AFR Base Units’ that allows the base units to be recorded in the ECU calibration memory. If this is unavailable, you can create your own using dynamic chained units in user scalars.

Firstly, create your required User Scalars:

[USERSCALAR,AFR Custom,AFR,...] // for exotic fuels
[USERSCALAR,AFR Methanol,afr:AFR Gasoline,...]
[USERSCALAR,AFR Gasoline,afr:AFR Methanol,...]
[USERSCALAR,AFR Diesel,afr:AFR Diesel,...]
// etc

Then create an Enumeration/Option List with these User Scalars:

[ENUM=AfrUnitList,0,AFR Custom,1,AFR Methanol,2,AFR Gasoline,3,AFR Diesel, ...etc]

Then create the Option for the Enumeration:

[AFR Units,,ol(AfrUnitList),...]

Finally, create a new definition for AFR Units using the Option:

[USERSCALAR,AFR Units,O[AFR Units],...]

You will now be able to select the appropriate User Scalar from the AFR Units Option.

Otherwise, the base unit choice must be stored externally to the ECU and GWv4 will not remember your choice. There are a few ways to accomplish this:

  • Reload the same calibration file every time you connect the ECU.

  • Override the base unit to a particular choice for any or all of the following: ECU types, versions, current project, calibration files on your PC. However, this may only be desirable if you are only ever working with a single fuel type.

Select Units / Scaling..., scroll down to the desired unit name and click ‘…’ on the right hand side next to the current unit.

Configure Units Override Configure Units Override

  • Save units whilst in the Configure Units / Scaling window and reload then when needed.

  • Change the default AFR units to be afr:LA and calibrate the reading to read 1.0 at the stoichiometric ratio. You can then select AFR for different fuel types from that. However, any other calibrations would also need recalibrating because their AFR offset and AFR scalar will be wrong.