I can't seem to get a knock retard histogram or any at that. I can view histograms on my WS6 and my girlfriends GTP, but when I plug into my friends HHR or my Cobalt I keep getting this message
This Histogram is not supported with the current loaded parameters.

If this Histogram references Tables, it is possible that the vehicle
you are connected to does not support these Tables. It is also possible
that the sensor required for the Table is not found in the loaded
parameters.

If this Histogram references Sensors, it is possible that the sensor
required is not found in the loaded parameters.

If this Histogram references PIDs, it is possible that the PID required
is not found in the loaded parameters.

You will find all of your loaded parameters located on your Table Display.
To add more parameters, right click the table display and click insert.

For example, if you have a histogram built that maps Timing Advance
and you do not have Timing Advance inserted on your Table Display,
the Histogram will not function.