6
In addition to the information provided to the ECU by the various sensors, the user is also able to adjust the fuel delivery through the
use of the five adjustment knobs on the front of the ECU. The user is able to adjust fuel delivery for Choke, Accelerator Pump, Idle,
Main, and High RPM settings. A detailed description of each adjustment is given below. Refer to Figure 2 during the discussion of
each of the adjustments.
The fuel map that is programmed into the digital ECU is comprised of 256 individual points. Each point has a throttle position and rpm
value assigned to it. These values are used by the digital ECU to determine the appropriate fuel delivery when the system is in
operation.
Fuel Map Areas of Adjustment
Figure 2
MAIN
The MAIN adjustment knob allows the user to adjust the fuel delivery of the entire fuel map 50% above or below the values set at the
factory. Rotating the knob clockwise will raise the fuel map vertically, therefore increasing the fuel delivery for all points in the map.
Rotating the knob counter-clockwise will lower the map vertically, therefore decreasing the fuel delivery for all points in the map.
NOTE:
In tuning the system, the MAIN is the first value to be adjusted. All other adjustments are made AFTER the MAIN has been
properly set.
IDLE
The IDLE adjustment knob allows the user to adjust the fuel delivery in the idle region of the fuel map 30% above or below the values
that are set at the factory. This is accomplished by moving the lower part of the fuel map either up or down along a hinged horizontal
line as indicated in Figure 2. Adjustments to the idle region of the fuel map are made AFTER the MAIN Adjustment knob has been
properly adjusted. Turning the knob clockwise increases the fuel delivery, while a counter-clockwise rotation decreases the amount of
fuel delivered to the engine during idle.
HIGH RPM
The HIGH RPM adjustment knob allows the user to adjust the fuel delivery for engine speeds over 3000 rpm 50% above or below the
values that are set at the factory. This is accomplished by moving the fuel map either up or down along a diagonal hinged line as
indicated in Figure 2. Turning the adjustment knob clockwise increases the fuel delivery, while a counter-clockwise rotation decreases
the amount of fuel delivered to the engine at high engine speeds.
ACCEL PUMP
The ACCEL PUMP adjustment knob allows the user to adjust the addition of fuel for acceleration 50% above or below the value set at
the factory. Rotating the adjustment knob clockwise results in additional fuel being added to the fuel enrichment set at the factory, while
rotating the adjustment knob counter-clockwise will result in less fuel being added during acceleration. The proper adjustment is made
while performing acceleration tests which are described later on in this section.
