Lambda control HFM-SFI function - GF07.51-P-3011D

ENGINE 104.942 /945 /992, 111.960 /961 /970 /977 with CODE (620a) Vehicles with catalytic converters

ENGINE 104.995, 104.941 up to 31.7.96 except CODE (498) as of Model Year 97 Japanese version except CODE (491) as of Model Year 97 U.S. version with CODE (620a) Vehicles with catalytic converters

ENGINE 111.974 except CODE (491) as of Model Year 97 U.S. version with CODE (620a) Vehicles with catalytic converters

ENGINE 104.943 /944 /991 /994, 111.944 /975 up to 31.7.96 with CODE (620a) Vehicles with catalytic converters

ENGINE 111.946 up to 31.5.98 with CODE (620a) Vehicles with catalytic converters

ENGINE 111.945 up to 31.5.98 in MODEL 208.335 with CODE (620a) Vehicles with catalytic converters

ENGINE 111.921 /942 up to 31.8.98 with CODE (620a) Vehicles with catalytic converters

ENGINE 111.945 up to 31.8.98 in MODEL 202.020 /080 with CODE (620a) Vehicles with catalytic converters

Fig 1: Identifying Lambda Control HFM-SFI Function

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The mixture composition should stabilize within the narrowest possible limits around = 1 in order to achieve high conversion of the exhaust gases in the catalytic converter.

The O₂ sensor reacts to the concentration of oxygen in the exhaust and transmits an appropriate voltage signal to the engine control module for fuel injection which thereupon alters the mixture composition so as to achieve a mixture composition of = 1 in all operating states of the lambda control. This procedure is constantly repeated (control loop), the frequency being dependent on engine load and speed.

The lambda control functions (close-loop control mode) in the following operating conditions:

Coolant temperature > 60°C (HFM-SFI)
O₂ sensors have reached operating temperature
Idle speed/ part load
Inertia fuel shutoff not active

Fig 2: Lambda Control Functions (Close-Loop Control Mode) Operating Conditions Chart

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

HFM-SFI control module - position/ task/ design/ function		GF07.51-P-4103D
O₂ sensors upstream of TWC - position/ task/design/ function		GF07.04-P-4103F
O₂ sensor heater function - function		GF07.61-P-3025F
Coolant temperature sensor - position/ task/design/ function	Engine 104/111 (B11/3)	GF07.04-P-5026GA
	Engine 104/111 (B11/4)	GF07.04-P-5026G
Hot film mass air flow sensor - position/ task/design/ function	Round connector with bayonet lock	GF07.07-P-4118E
	5-pin connection, intake temperature sensor integrated	GF07.07-P-4118G
Self-adaptation of mixture formation - function		GF07.61-P-3030F
Fuel injection valve - position/ task/ design/function		GF07.03-P-5004F
Two-sensor control - function		GF07.61-P-3020F
Three-way catalytic converter - design/ function		GF49.10-P-3002F