Log Map

Log Maps monitor and store a pre-defined channel into the map at sites corresponding to those of a base map. For example, a Lambda Log Map would log the lambda channel, based upon the Fuel Map. As the load and speed approach a particular site in the Fuel Map, the value of lambda is logged into the Lambda Log Map at the corresponding site. As more values of lambda are collected for that site, the site value is averaged out. As engine load and speed changes, the initially empty Log Map is built up to show how lambda changes across the entire load and speed map.

Log Map Views

There are various view to choose from:

  • Log Map Controller allows log mapping and auto mapping to be configured.

  • Log Map Grid 2D view of the values of the logged channel that have been stored for sites in the base map. Similar to Map Grid views. It will initially be empty and will be filled once the desired channel is being logged.

  • Log Map Graph 3D version of the Log Map Grid. Similar to Map Graph views.

  • Log Map Slice displays a slice through the Log Map in the same way as Map Slice views.

  • Log Map Site Target displays the current site positioning in the same way that Map Target views do.

  • Log Map Target Grid 2D view of the target values used in auto mapping. Similar to Map Grid views.

  • Log Map Target Graph 3D version of the Log Map Target Grid. Similar to Map Graph views.

  • Log Map Target Slice displays a slice through the Log Map target in the same way as Map Slice views.

Auto mapping

Some log maps are configured to change their base map according to the difference between the Log Map and an additional map called the target map. The target map can be viewed by displaying a Log Map Target.

The values in the target map should be set to the desired values, for example, for an AFR (gasoline) target map, the map would normally be set to around 14. GWv4 attempts to adjust the base map such that the Log Map site values are as close to the target map site values as possible.

Auto mapping can be configured and enabled using the Log Map Controller view. For more information on how to use auto mapping, see

Detailed Description

Every time the logging channel is read from the ECU (rate is variable), the value is evaluated for log/auto mapping.

Overview of Algorithm

  • Test if site should be logged (filtering stage).
  • Calculate Weighting.
  • Update map if auto mapping.
  • Log the value and weight (if auto mapping, weight is reset to zero).

Filtering

Before a value is considered for logging/auto mapping it must pass a number of tests:

  • The current site should be valid.
  • The secondary filtering channel (if any) should meet constraints defined in the ECU Definition file.
  • The tertiary filtering channel (if any) should meet constraints defined in the ECU Definition file.
  • The percentage distance in either X or Y direction from dead-center of the site should be less than “Site Accuracy” / 2.
  • The time that the site has been covered for should exceed the Remove Time (which is set in the ECU along with Weight Time defined below and can be edited for your own user log maps).

“Weight Before Change” is a value in milliseconds and is set in the Log Map Controller.

Calculations

The site weighting calculation is based on the time at the site and the distance from dead-center of the site:

Weight = TimeWeight * Xweight * Yweight

WeightDiffTime = “Weight Time” - “Remove Time"        (these values are in the ECU Definition file)

TimeWeight

If: “Milliseconds at Site” >= “Weight Time”, 
    TimeWeight = 1

Else:
    TimeWeight = (“Milliseconds at Site” - “Remove Time”) / WeightDiffTime

Xweight, Yweight

If:(site offset percentage < 100 percent weighting / 2) 
    weight = 1

Else: 
    weight = (site accuracy – site offset) / (site accuracy – 100 percent weighting)

The weighting value is applied to the extant weighting value:

Weight = TimeWeight * Xweight * Yweight
NewWeight = Weight + Old Weight

The new (raw) value to be entered into the Log Map:

New Value = ((Log Channel (RAW) * Weight) + (Old Value * Old Weight)) / New Weight

The base map (e.g. Fuel map for lambda log) is updated only if the weighting constraint is satisfied (when New Weight >= Weight Before Change). Otherwise the new values are simply written into the Log Map.

Change value calculation for Auto Mapping

Change = (Target Map Value - Log Map Value) * Error multiplier + Error additive

This can be applied as either:

  • Additive: Map + Change.
  • Percentage: Map + (Map * Change / 100).

When the site is updated in the map, the ’time at site’ is reset, and the site weighting is set to zero.