Precision Turbo and Engine BigStuff3 GEN3 PRO SEFI (LS1) System Hardware & BigComm Software - Manual (Page 70)

BigStuff3 Pro SEFI System (LS1)
Version 1.0 69
40. Throttle Follower
Throttle bodies used with electronic fuel injection systems have an air by-pass channel molded or
machined into the valve body to allow air to be bypassed around the throttle blades when they
are fully closed. The air entering the engine through the bypass channel is used to control the
engine idle speed. The amount of air needed to maintain a desired engine speed varies
depending on engine coolant temperature, camshaft overlap, etc. The Idle Airspeed Control
(IAC) motor (and plunger) control the amount of air allowed to be bypassed around the throttle
blades.
The “Throttle Follower” table allows the user to set a relationship between throttle blade angle
and the position of the IAC metering valve (plunger). This is required to keep the engine from
stalling when the throttle position changes from some percent (%) open to fully closed very
quickly.
The fixed values along the bottom of the table below represent the percent (%) throttle position
which increase in increments of eight (8) percent. The input values above the fixed numbers are
used by the ECU to position the IAC metering valve (plunger), inside the bypass channel. The
position of the metering valve (plunger) will vary depending on throttle position. The default
values, configured with the system as shipped, will work with a majority of engine applications.
While the engine is running, a “real-time Ellipse” will move within the Throttle Follower
Table relative to the current TPS (%) “operating point”. Use it as a point of reference to help
calibrate the Throttle Follower table.
To change a value in the Throttle Follower 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.