Precision Turbo and Engine BigStuff3 GEN3 PRO SEFI System Hardware & BigComm Software - Manual (Page 68)

BigStuff3 Pro SEFI System
Version 2.1 – February 2011 61
29. AFR Parameters (F11 – “Quick Key”)
The Air/Fuel Ratio (AFR) Parameters table allows the user to configure control parameters
associated with closed loop fuel control, using the WBO2 sensor.
The following paragraphs will describe the function of each control parameter.
RPM On & RPM Off Inputs
 RPM On – Defines the RPM the engine needs to exceed before the ECU will allow the system
to go into closed loop fuel control using the O2 sensor.
 RPM Off – Defines the RPM the engine needs to fall below before the ECU will not allow the
system to operate in closed loop fuel control. The RPM Off value needs to be at least 100 RPM
less then the RPM On value.
Max Step and Gain (for the Oxygen Sensor) Inputs
 Maximum Step – Defines the aggressiveness (number of steps) of the O2 sensor when it
updates the O2 correction factor. The step sizes can go from 1% to 12%. For example, if the
O2 sensor needs to make a 15% correction and the Step Gain is set at one (1) the O2 correction
loop will go through 15 iterative steps to close the O2 correction gap. If the Step Gain is set to
12, the sensor will go through only a few steps to close the O2 correction gap.
 Gain % - Gain can range from 1% to 50%. The gain function subtracts the desired air fuel ratio
from the actual air fuel ratio then multiplies the difference by the user defined gain % and
affects the closed loop response.
Hot & Cold Delay Inputs –
 Hot Delay - This input (in seconds) is the time the ECU waits before allowing the system to go
into closed loop fuel control when the engine coolant is above 60
o
F.
 Cold Delay - This input (in seconds) is the time the ECU waits before allowing the system to
go into closed loop fuel control when the engine is below 60
o
F.
The Minimum Coolant Temperature threshold described below also affects the Hot and Cold Delay
parameters.
Minimum Coolant Temperature
The minimum coolant temperature input is the temperature threshold the engine coolant needs to
exceed before the ECU will let the system go into closed loop control.
To make changes to the values in these tables, use the left or right arrow keys to move the cursor to the
cell to be changed. Input the desired value and click on “OK” at the bottom of the table.