CALIFORNIA Turbo Diesel Series
Exhaust gas recirculation takes place when certain parameters are met: When coolant temperature is greater than 104°F (40°C) and less than 195°F (90°C). Engine speed is more than 500 RPM. When a load signal is sent to the injection pump (auxiliary units switched off, shift lever in position "P" or "N".
The resistance of the coolant temperature sensor drops with increasing coolant temperature and supplies the input signal for the ECU.
When engine speed is more than 500 RPM (but less than 1000 RPM), the vacuum converter is energized and provides vacuum to the EGR valve. When vacuum is applied to the EGR valve, it opens completely and permits maximum EGR.
When engaging the transmission and turning on an electrical consumer (headlights, radio etc.) a certain engine load is exceeded. The vacuum converter is then de-energized and the vacuum to the EGR valve is reduced and EGR is eliminated.
When engine speed is more than 1000 RPM in a partial load range, the vacuum converter is also energized and provides maximum EGR. With increasing engine load the current is reduced and at a given load signal the vacuum converter will be de-energized. As the current is being reduced, the vacuum on the EGR valve and the EGR volume are reduced.
In addition, the recirculated air safety valve is completely opened at an engine speed greater than 1000 RPM and at the corresponding load signal. With increasing altitude, the compensating capsule installed in the control unit will reduce the EGR volume according to the barometric pressure.