Exhaust Gas Recirculation, Function

Exhaust Gas Recirculation, Function

ENGINE 111.974 with CODE (491) as of model year 97 USA version




89 EGR valve
B2/5 Hot film mass air flow sensor
B11/4 Coolant temperature sensor
B37 Pedal value sensor
L5 Crankshaft position sensor
M16/1 Electronic accelerator (EA)/cruise control (CC)/idle speed control (ISC) actuator (further designation: M16/6 throttle valve actuator)
N3/10 ME-SFI control module
Y27 EGR switchover valve

Exhaust gas is recirculated as a function of the map stored in the ME-SFI control module provided the following conditions are met:
- Coolant temperature between 60°C and 110°C
- Engine speed <3500 rpm
- Part throttle

The EGR switchover valve (Y27) is actuated at the GND end and switches vacuum to the EGR valve, as a result of which this valve is opened.

Exhaust with a low oxygen level is drawn in in line with the position of the throttle valve. The fuel/air mixture thus contains a low level of oxygen.
The result is that the combustion temperature drops and the formation of NOx is reduced.