Exhaust gas recirculation function

P14.20-0211-76

up to engine end no.:

016 839 (with manual transmission)

014 488 (with automatic transmission)

101 EGR valve

102 Pressure regulating flap vacuum unit

103 Pressure regulating flap

107 Exhaust manifold

107/3 Corrugated pipe

110/6 Charge air pipe

B2/5 Hot film mass air flow sensor

Y31/4 EGR/pressure regulating flap vacuum transducer

P14.20-0266-76

as of engine end no.:

016 840 (with manual transmission)

014 489 (with autoamtic transmission)

101 EGR valve

107 Exhaust manifold

107/3 Corrugated tube

110/6 Charge air pipe

B2/5 Hot film mass air flow sensor

Y31/1 EGR vacuum transducer

P07.13-0392-11

Map of air mass flow

E Injected quantity

L Air mass

M Engine speed

Task

Reducing the oxides of nitrogen (NOx), der Kohlenwasserstoffe the hydrocarbons (HC) und der Partikel and the paraticulates (PM).

Function

The exhaust gases are recirculated in line with the maps stored in the DFI control module (N3/8) as soon as the following points are met.

 Coolant temperature <95 °C

 Battery voltage 11–14 V

 Part load (quantity up to 35 mg/stroke)

 Intake air temperature 0-60 °C

 No inertia fuel shutoff activated

 At idle speed max. 60 sec. (afterrunning)

 Position sensor at CTP stop (0%)

 Engine speed 610-2900 rpm

The DFI control module (N3/8) controls the appropriate quantity of exhaust gases which are recirculated for the particular operating state by means of the air mass, on the basis of the signals supplied by the hot film mass air flow sensor (B2/5).

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The quantity of exhaust gases recirculated is set in each operating point so as to achieve the maximum possible reduction of NOx.

At idle speed, with accelerator not operated, exhaust gas recirculation remains actuated for up to 60 seconds.

Engines with pressure regulating flap: The EGR/pressure regulating flap vacuum transducer (Y31/4) is actuated at the ground side and controls the vacuum to the EGR valve (101) and to the pressure regulating flap vacuum unit (102).

The positioning forces of the EGR valve and pressure regulating flap vacuum unit are graduated in such a way that the EGR valve (101) is first of all opened fully as the vacuum of the EGR/pressure regulating flap vacuum transducer increases, and only then is the pressure regulating flap (103) increasingly closed.

Engines without pressure regulating flap: The EGR vacuum transducer (Y31/1) is actuated at the ground side and controls the vacuum to the EGR valve (101).

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