Run Mode

Once the engine starts and is operating normally, the timing will be controlled by the computer, based upon information received by the data sensors.

Spark timing and dwell cannot be adjusted in the run mode. If the computer fails, the system will go into the start mode. This enables the vehicle to be driven in for repair, but performance and fuel economy will be poor. If the start mode fails, the engine will not start or run.

The amount of spark advance is determined by engine speed and engine vacuum, based on the following conditions:

• Advance based upon engine vacuum is allowed by the computer when the carburetor switch is open. The amount of advance is programmed into the computer and is proportional to the amount of vacuum and engine RPM.
• Advance based upon engine speed (RPM) is allowed by the computer when the carburetor switch is open and advance from vacuum is not changing. This advance from speed is programmed into the computer, controlled by engine RPM, and will build at a slow rate. If carburetor switch closes, advance from speed will be canceled.