Precision Turbo and Engine BigStuff3 GEN3 PRO SEFI System Hardware & BigComm Software - Manual (Page 81)

BigStuff3 Pro SEFI System
Version 2.1 – February 2011 74
41. Desired Idle RPM
The Desired Idle Rpm table allows the user to set the desired engine RPM as a function of coolant
temperature. To configure the table, input the desired engine RPM for the each temperature shown at
the bottom of the table. The ECU controls the idle speed so transitions between temperature ranges are
not noticeable.
Note: The TPS needs to be set properly for this input to function properly. See
TPS_Configuration for
further assistance.
While the engine is running, a “real-time Ellipse” will move within the Desired Idle Rpm
Table relative to the current engine coolant temperature “operating point”. Use it as a point of
reference to help calibrate the Desired Idle Rpm table.
To change a value in the Desired Idle Rpm table, move the cursor using the PC’s mouse or arrow
keys to the cell to be changed. Input the desired value and hit
“Enter”
to save the change.
.
42. Idle Spark
The Idle Spark control function helps maintain idle quality by introducing bi-directional spark timing
as an additional control variable. This is a very useful idle control function!
Note: Idle spark control is only active when the actual throttle position (the TPS % value shown in the
dash) is below the Max TPS for Idle value inputted into the set up table. For example, “Idle Spark”
control will not function if the Max TPS for Idle value (inputted into the
OPerating_Configuration
table) is set to 4%, and the actual TPS % is 5%, with the throttle blade completely closed.
“Idle Spark” control will function if the actual throttle position (TPS %) is 2% and the “Max TPS for
Idle” value is set at 4%. In this case, “Idle Spark” control would function until the throttle blade was
opened above 4%. Back to
TPS_Configuration
The fixed values, below the table, are the ECU’s reference points for how many RPM the engine is
operating at above or below the “Desired RPM.” The fixed values define the active control (RPM)
range. The active range is from 256 RPM below the “Desired” RPM to 224 RPM above the “Desired”
RPM.
The bi-directional input table allows the user to quickly advance the timing (left side of the input table)
when the RPM begins falling below the “Desired RPM” setting. Once the timing is advanced it needs
to be retarded (right side of the input table) as the engine RPM begins increasing. The zero point in the
table is equal to the user defined, “Desired” RPM.