MoTeC Global Forum

Is it possible to subtract the value of one channel from another
For example to subtract boost pressure from fuel pressure to monitor fuel pump operation
If not can the calculation be performed in a PDM and then sent back to the C127 to display

You can use one of the 3D User tables for that. One axis for Fuel pressure and the other for MAP (or Boost). The output is Relative Fuel Pressure which you can then use for an Alarm.


In this case the x-axis is Fuel pressure and the y-axis is Manifold Absolute pressure.
If one parameter is coming from an ECU data stream and the other from the dash you might get some anomalies due to timing alignments. To avoid having to allow time delays before alarms it is best if both parameters come in via the same data stream or else have the dash measure both.

Thankyou

I have one 3D table left so I can give this a try, both channels coming across from my M800 so I shouldn't have any issues with timing alignments