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should "open circuit", causing a lean condition, the back up automatically takes place. If the TPS "short circuits", causing a rich
condition, you must remove the wire harness connector from the TPS. The idle will be richer and top speed will be limited in this
mode. DO NOT operate for an extended period of time in this mode.
WARNING! The throttle position sensor may become damaged if exposed directly to liquid. Protect the TPS when
washing the engine.
The oxygen sensor provides information on whether the engine is running rich or lean. Even though the oxygen sensor is
heated, the ECU will continue to operate in an open loop mode for a short period of time after initial start-up. This combined
information is then used by the ECU to adjust the fuel delivery to the engine.
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 13 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 13
14.1 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.
14.2 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 13. 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.
