Precision Turbo and Engine BigStuff3 GEN3 PRO SEFI System Hardware & BigComm Software - Manual (Page 78)

BigStuff3 Pro SEFI System
Version 2.1 – February 2011 71
To change a value in the Cranking 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.
Once the engine starts (the ECU will detect the rapid change in engine speed) the ECU will ignore the
Cranking table and begin using inputs from the After Start Delay (see section 37).
36. AfterStart Delay
Once the ECU detects the engine has started, it uses the vehicle coolant temperature sensor and inputs
from the After Start Delay table to decide when to introduce the After Start Correction Fuel. The
ECU begins counting the crankshaft interrupts. When the ECU counts off the number of interrupts
defined in the After Start Delay table, for the current engine operating temperature, the ECU adds the
After Start Correction Fuel. The delay mentioned here is very, very short. The table below shows
that nine (9) interrupts were used at –14
o
and 16 interrupts at 230
o
. One can appreciate how quickly
nine (9) or sixteen (16) crankshaft interrupts occur at an engine speed of 800 RPM.
While the engine is running, a “real-time Ellipse” will move within the After Start Delay table
relative to the current engine coolant temperature “operating point”. Use it as a point of reference to
help calibrate the After Start Delay table.
To change a value in the After Start Delay 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.
37. AfterStart Correction
As outlined above, the ECU delays the introduction of After Start Correction fuel once the engine
starts.
The table below allows the user to define the amount of After Start Correction fuel to be added as a
function of coolant temperature. The After Start Correction fuel is added synchronously as a percent
(%) of the base pulse width (defined in the Fuel table). As you will notice in the table, the percent (%)
of fuel added is greater at the two temperature extremes. The largest amount of fuel is needed when
the engine is coldest. A larger amount of fuel is also added when the engine is hot versus the mid
range temperatures, to release any vaporized fuel that may have “boiled” in the fuel rail(s) during a hot
soak.
While the engine is running, a “real-time Ellipse” will move within the After Start Correction table
relative to the current engine coolant temperature “operating point”. Use it as a point of reference to
help calibrate the After Start Correction table.