Exhaust Gas Recirculation (EGR)

2. Exhaust gas recirculation (EGR)

Exhaust gas recirculation occurs, as long as the following conditions are fulfilled:

Engine 602.962
^ Coolant temperature between 80°C and 110°C.
^ Engine speed:
680-800 rpm = Reduced EGR
800-3500 rpm = EGR according to map values
above 3500 rpm = Decreasing EGR,
^ Volume of EGR dependent on atmospheric pressure,
^ Volume of EGR dependent on intake air temperature,
^ Fuel rack travel less than 9 mm,
^ Battery voltage 11-14 volts.

Engine 603.970
^ Coolant temperature between 60°C and 110°C,
^ Engine speed:
800-2800 rpm = EGR according to map values
above 2800 rpm = Decreasing EGR,
^ Volume of EGR dependent on atmospheric pressure,
^ Volume of EGR dependent on intake air temperature,
^ Fuel rack travel less than 9 mm,
^ Battery voltage 11-14 volts.

Corresponding to the input signals from the sensors-for examples: fuel rack travel, engine speed etc. - the EDS control unit calculates the corresponding exhaust gas recirculation volume for the operating conditions at the time.The vacuum transducer is actuated by a current and controls a corresponding vacuum to the EGR valve.

The EGR volume is reduced as engine speed and load increase.
That means:
With an increase of control current the EGR volume rises;
With a decrease of control current the EGR volume declines.

Block Diagram, EGR:

The EGR system works as an open loop control system, with the EGR valve, vacuum transducer, air flow sensor, engine speed sensor and EDS control unit.