F. Total Operation USA Model Year 1984 California
OPERATION EXHAUST GAS RECIRCULATIONF. Total operation USA model year 1984 California
EGR proceeds after the following points have been met:
^ Coolant temperature > 40°C and < 90°C.
^ Engine speed > 500/min.
^ Load signal of injection pump:
Idle speed auxiliary units switched off. Selector lever in position "P" or "N".
Partial load auxiliary units switched on and selector lever in driving position.
The resistance of the coolant temperature sensor changes in dependence of the coolant temperature and thereby provides the input signal for the EGR electronic control system.
Engine speed > 500/min < 1000/min
In this rpm range (without load) the pressure converter (84) is activated with approx. 530 mA. The result is a vacuum at EGR-valve of approx. 290 mbar. The valve opens completely; max. possible EGR will result.
By engaging a driving position and switching on auxiliary units, a given load signal will be exceeded. The pressure converter will be deenergized and the vacuum toward EGR valve will be exhausted. There will be no more EGR.
Engine speed> 1000/min
At engine speeds> 1000/min the pressure converter is also activated with approx. 530 mA in partial load range. Max. possible EGR will result.
With increasing load the current is reduced to 370 mA and the pressure converter will be deenergized as from a given load signal. In parallel with the reducing current the vacuum on EGR-valve will be exhausted and the EGR quantity will be reduced.
At 370 mA the vacuum on EGR-valve amounts to 190 mbar. This is the closing point of the EGR-valve; there will be no more EGR.
In addition, the circulating air safety valve will be completely opened at an engine speed > 1000/min and the respective load signal of the circulating air safety valve.
With increasing altitude a bellows integrated in control unit serves to reduce the EGR quantity in accordance with the prevailing air pressure.