Cold Advance Control
The cold advance control circuit is designed to advance injection pump timing about 4 degrees during cold engine operation. This circuit is activated by the ECM, through the cold advance relay, to energize the cold advance solenoid. The ECM opens the circuit when coolant temperature is above 95°F (35°C).
Below the switching point, and with ignition on, the cold advance solenoid is continuously energized without the engine running. Below the switching point and the engine running, injection pump housing pressure is decreased from 10 psi (.70 kg/cm2 ) to zero, which advances injection pump timing by about 4 degrees. As engine warms-up, the cold advance solenoid is de-energized and the injection pump housing pressure is returned to 10 psi (.70 kg/cm2 ).