Print; Communications; Tuning Tips; Tuning Tips For A System With An Oxygen Sensor (Closed Loop) - Holley MPI PRO-JECTION Installation Tuning And Troubleshooting Manual

Fuel injection system

Table of Contents

1 - Injection Volume - Use this selection to modify the Injection Volume map. Move the cursor with the arrow keys to the

desired point on the map you wish to modify. Use "F2" or "F3" to raise or lower the Injection Volume

at this point by 1unit each keystroke. Use "F4" or "F5" to raise or lower Injection Volume across the

entire load line by 1unit for each keystroke. Use "F6" or "F7" to raise or lower the Injection Volume

along the RPM line by 1unit each keystroke. A legend is provided in the lower right corner of the

screen for reference. Press "Esc" to exit.

2 - Oxy Trigger Voltage - Use this selection to modify the Oxygen Trigger Voltage map. This display is in graphical form.

Place the cursor in the area you wish to modify. Press "F2" to raise the area, or press "F3" to

lower. These values can also be easily changed in the Edit mode. The Oxygen Trigger Voltage

has a relatively minor effect on the fuel/air ratio and therefore it should not be necessary to change

these values. Press "Esc" to exit.

3 - Spark Advance - Use this selection to modify the Spark Advance map. Use "F2" or "F3" to advance or retard the spark

at a point on the map. Use "F4" or "F5" to advance or retard the spark along a load line. Use "F6" or

"F7" to advance or retard the spark along a RPM line. Maximum Spark Advance is 41.8 . Press "Esc"

to exit.

4 - Accel Comp - Use this selection to modify the Acceleration Compensation map. Use "F2" to raise the amount of fuel

added during acceleration and "F3" to lower the amount of fuel added. In both cases, the Acceleration

Compensation is added or subtracted along an entire RPM line on each keystroke. Press "Esc" to exit.

14.4.4 Print

The Injection Volume, Spark Advance, and Accel Comp maps can be printed using this selection. This option requires that a dot

matrix printer be connected to your PC. Simply highlight the desired map and press "enter". Press "Esc" to exit this selection.

The Communications allows the user to choose between the COM 1 and COM 2. COM 1 is normally the default setting on most

PC's.

An IBM compatible personal computer (preferably a laptop for portability) must be connected to the MPI PRO-JECTION ECU.

The goal of this tuning process is to obtain a fuel map that is slightly rich. The advantage with this system is the personal

computer can be used to monitor and change various engine parameters during the tuning process. If one is operating the

system with an oxygen sensor, it becomes very easy to make fuel map changes and monitor their affect with the oxygen sensor

compensation value.

The user can use the Data Monitor option in the personal computer software to determine the amount of fuel correction from the

Oxy Comp value. The best performance results will be obtained if the engine is mapped slightly rich (10 - 20%). This value is

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