Driver Demand Maps

Posted: 
Friday, December 9, 2016 - 11:00

The driver demand maps are relatively simple - they convert throttle input (what you the driver are demanding) and engine speed into a requested injection quantity in mg/stroke.

EU2 Disco 2

78 Map
Map051 - Driver Demand - High Range
Map052 - Driver Demand - Low Range

79 Map
Map053 - Driver Demand - High Range
Map054 - Driver Demand - Low Range

EU3

Map069 - Driver Demand - High Range
Map070 - Driver Demand - Low Range

Axis Values

  • X-axis: Throttle %
  • Y-axis: Engine Speed (RPM)
  • Z-axis: Inject Quantity (mg/stroke)

Using data logging

Nanocom logging does not expose the throttle %, despite the value being returned in the same request as the way voltages.

To approximate the throttle % from TPS 1 voltage:

estThrottle% = 39.5 * TPS1 voltage - 35.55

Ignore the negative percentages, as these occur in the dead band of the pedal.
It's not exact. From my logs 2.000V = 43.18% and from the formula above 2.000V = 43.34% (using a three-way pedal). An alternative method is to use a cheap OBD-II interface to log RPM and Throttle %, as both these items are available as OBD-II PID's.

Using the calculated Throttle % and RPM data you can find precisely where on the throttle map you are driving under specific conditions.

As an example, the images below show a scatter plot of the live data for RPM and Throttle % with the breaks set to match axis header values. The corresponding EU2 High Range Driver Demand map is shown beneath the live data.

Driver Demand logged hits

Driver Demand map - EU2 Auto