Throttle Opener Control System

This system is set at the factory and adjustment is not normally required. If adjustment is needed, proceed as follows:

1. With engine at normal operating temperature and choke fully open, connect vacuum gauge to intake manifold, and tachometer to engine. Disconnect wiring harness to throttle opener solenoid to ensure solenoid is OFF.
   Fig 1: CONTROL VALVE OPERATING NEGATIVE PRESSURE (OPERATING VACUUM)

   Courtesy of NISSAN NORTH AMERICA, INC.
2. Connect servo diaphragm vacuum hose to intake manifold. With high vacuum, servo diaphragm should raise engine speed to 1650-1850 RPM. If RPM is not correct, adjust by turning adjusting screw clockwise to raise RPM and counterclockwise to lower RPM.
3. When atmospheric pressure is known, operating pressure is found, on chart, by following the arrow in line "A" from atmosphere to operating pressure. When altitude is known, operating pressure is found by following arrow in line "B" from altitude to operating pressure.
4. Disconnect servo diaphragm vacuum hose from intake manifold and connect it to vacuum control valve. Connect vacuum hose of control valve to intake manifold. Place transmission in "P" or "N" (Auto. Trans.) or neutral (Man. Trans.). Increase engine speed to 3000 RPM under no load and release throttle rapidly.
5. Adjust vacuum control valve adjusting screw so that operating pressure is held for a few seconds as engine speed decreases from 3000 RPM to 1000 RPM as shown on chart.