Precision Turbo and Engine BigStuff3 GEN3 PRO SEFI (LS1) System Hardware & BigComm Software - Manual (Page 84)

BigStuff3 Pro SEFI System (LS1)
Version 1.0 83
relative to a rate of throttle change (dTPSdt). The asynchronous pulse can be modified relative
to the throttle position where the acceleration event occurred (AE Position Correction). Below,
is a description of how the TPS Transient Fuel requirements are calibrated using the dTPSdt and
AE Position Correction tables.
55. dTPSdt
The first TPS Transient Fuel control table is dTPSdt. It can be compared to a carburetor’s
accelerator pump shot. The ECU uses the dTPSdt table value to compute the size of the
Asynchronous Pulse Width (APW) for a given rate of throttle change. It does so by sensing the
rate of the throttle change and then using the corresponding dTPSdt table value to calculate the
size of the asynchronous pulse width. For example, if the ECU detected a throttle change of 10
degrees / second (dTPSdt), it would immediately look up the corresponding dTPSdt table value
of let’s say 2ms. After the asynchronous pulse is looked up, the ECU then uses AE Position
Correction table (see below) to modify the asynchronous pulse size relative to the throttle
position at which the dTPSdt event occurred. Note: If the dTPSdt table value is zero, no TPS
transient fuel will occur.
Working from left to right, each input cell in the dTPSdt table represents a 1% change in throttle
angle for a total percent change of 15%. This is plenty of resolution since the ECU looks for
changes every 20 milliseconds. As a reference point, it typically takes approximately 250
milliseconds for a person to slam the throttle open.
While the engine is running, a “real-time Ellipse” will move within the dTPSdt table relative to
the current dTPSdt “operating point”. Use it as a point of reference to help calibrate the dTPSdt
table.
To change a value in the dTPSdt 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. The values
need to be larger as you work from the left to right. The greater the throttle angle rate of change,
the larger the dTPSdt table value needs to be.