ENGINE   113.940 /941 /942 /943 /948 /960 /961 /963 /965 /966 /967 /968 /969 ENGINE   137.970

P07.61-0374-09

Example of ME-SFI ignition system A16 Knock sensors B2/5 Hot film mass air flow sensor B6/1 Camshaft Hall sensor B11/4 Coolant temperature sensor B17 Intake air temperature sensor (on engine 104, 111, 112, 113 integrated in hot film mass air flow sensor) B37 Accelerator pedal sensor K40 Relay module model 170, 210 up to 2/97 K40/4 Fuse and relay module Model 202, 208, Model 210 as of 3/97, Model 163 designation F1 L5 Crankshaft position sensor M16/1 Electronic accelerator EA/CC/ISC actuator N3/10 ME-SFI [ME] control unit

N15/3 ETC [EGS] control unit N16/1 Base module model 129, 140 N47-1 ASR/SPS control unit N47-5 ESP / SPS [PML] / BAS control unit N54 RCL control unit R4 Spark plugs T1/1 Ignition coils Engine 104, 111: a two-spark ignition coil for two cylinders Engine 119, 120: one ignition coil for each cylinder Engine 112, 113: a double ignition coil for each cylinder X11/4 Data link connector CAN Data bus

Signal assignment Shown on engine 119 1 Crank angle 2 Cylinder ignition TDC 3 Signal from crankshaft position sensor (L5) 4 Signal from camshaft Hall sensor (B6/1) 5 Rpm signal TNA a Recognition of cylinder 1
		P07.61-0217-05

Function When the crankshaft is rotating, an alternating voltage is generated in the crankshaft position sensor by the teeth of the driven plate. In this case, each tooth generates an alternating voltage signal. No voltage is generated through the gap of 2 missing

teeth. The ME-SFI control unit detects the TDC position of the crankshaft with the 2nd negative slope after the gap.

If the signal from the camshaft Hall sensor is at 0 V ("low") at this moment, the ME control unit processes this in order to detect ignition TDC. This is used for actuating the ignition coils and the fuel injectors. The high voltage is distributed rotorlessly. Advantages of the rotorless high voltage distribution are: - significantly reduced electromagnetic interference level (no naked sparks) - no rotating parts - reduction in noise - reduced high voltage connections.

1. Determine ignition angle according to input signals, actuate ignition coils and release ignition spark . The ME-SFI control unit essentially analyzes the following signals for determining the ignition angle: - Engine load - Crankshaft position sensor - Camshaft Hall sensor - Coolant temperature sensor - Intake air temperature sensor/charge air. Coil ignition: The ME control unit interrupts at the point of ignition timing at the ground end the ignition coil primary circuit of the ignition coil. ECI ignition system (engine 137): The ME control unit actuates the output stages in the ECI ignition modules. The ignition angle can only be checked with the HHT/STAR DIAGNOSIS.

2. Ignition angle adaptation 2.1 Catalytic converter heating-up (warming-up) The ignition angle is continuously retarded for about 20 seconds in order to more rapidly warm up the catalytic converter to its operating temperature if: - coolant temperature at start > 15 °C and < 40 °C - Selector lever position P or N At the same time idle speed is increased by the idle speed control. 2.2 Idle speed To assist the idle speed control, the ignition angle can be retarded by as much as 36° crank angle or advanced by as much as 20° crank angle. Altering the ignition angle provides a more rapid control than altering the position of the throttle valve (idle speed control). 2.3 Deceleration fuel shutoff The ignition angle is briefly retarded when combustion is resumed (fuel injectors actuated) in order to prevent a sudden increase in torque.

2.4 Intake air temperature/coolant temperature The ignition angle is retarded under load, as a function of the intake air temperature and coolant temperature, in order to prevent any knocking tendency at high intake air and coolant temperatures. The ignition angle is "Retarded" if: - Intake air temperature > 35 °C - Coolant temperature > 105 °C In supercharged engines the charge air temperature is used as information for the ignition timing adjustment in place of the intake air temperature. The values of the retardation of the ignition angle of intake air temperature and coolant temperature are added together.

2.5 Transmission overload protection In order to protect the shift elements of the automatic transmission during power shifts (1-2-1, 2-3-2) from excessive thermal stresses, the ignition angle is briefly retarded during the gearshift and the engine torque reduced as a result. The ME-SFI control units are supplied with a signal for this purpose from the ETC control unit (N15/3) over the CAN databus. 2.6 ESP/ASR control mode In order to reduce the engine troque as rapidly as possible in the ESP/ASR control mode, the ignition angle is retarded by the throttle valve actuator (opening angle reduced) prior to the control mode being activated. The information from the ESP/ASR control unit is supplied over the CAN databus to the ME-SFI control unit. 2.7 Anti-knock control (AKC) If uncontrolled combustion (knocking) occurs at one or several cylinders, the ignition angle at the relevant cylinder or cylinders is "Retarded".

2.8 Smooth engine running analysis To restrain the three way catalytic converter from thermal overload through combustion misfiring and in order to keep the exhaust emission values, the smooth operation of the engine is continuously monitored. If combustion misfiring is identified at one or several cylinders, the corresponding fuel injection valves are no longer actuated after a certain number of misfires. Engine 104, 111, 112, 113, 119, 120: Smooth operation evaluation is performed through the signals of the crankshaft position sensor. Engine 137: Identification of combustion misfiring by means of ionic current signal, see ECI ignition system function.

2.9 Double ignition engine 112, 113, 137 Two spark plugs for each cylinder are beneficial because of the arrangement of the valves for achieving optimal emission levels and smooth engine running. Each spark plug is actuated separately by the ME-SFI control unit through its own ignition coil. On engine 112, 113 both ignition coils of a cylinder are combined to form a dual ignition coil. In the lower part load range up to approx. 2000 rpm both ignition sparks of a cylinder are triggered simultaneously. At moderate and high engine loads, the ignition sparks are triggered offset by as much as 10° crank angle. In this case,

The sequence of actuation is constantly varied in order to achieve a uniform wear of both spark plugs and to avoid deposits on only one side of the combustion chamber. For troubleshooting in the dual ignition system, it is possible to switch off one ignition circuit each with HHT or STAR DIAGNOSIS.

	ME-SFI ignition system function diagram	Engine 113	GF15.12-P-0001-01B
	ME-SFI control unit position/task/design/function		GF07.61-P-5000F
	ECI ignition system function	Engine 137	GF15.15-P-3000L
	Ignition coils, location/task/design/function	Engine 113	GF15.10-P-3102A
	Crankshaft position sensor, location/task/design/function		GF07.04-P-4116F
	Camshaft Hall sensor, location/task/design/function		GF07.04-P-4117F
	Spark plugs, location/task/design/function		GF15.10-P-3101F
	Intake air temperature sensor, location/task/design/function		GF07.04-P-2100F
	Hot film mass air flow sensor, location/task/design/function	Engine 113, 137	GF07.07-P-4118G
	Coolant temperature sensor, location/task/design/function	Engine 113, 137	GF07.04-P-5026A
	Electronic accelerator, location/design/function	Engine 113, 137	GF30.20-P-3010E
	Anti-knock control function		GF15.12-P-4024F
	Transmission overload protection function		GF07.61-P-4026F
	Overheating/pinging protection function		GF07.61-P-4027F
	Intake air temperature correction function		GF07.61-P-4028F
	ME-SFI synchronizing fuel injection and firing order function		GF07.61-P-4009F
	ME-SFI ignition system signal assignment	Engine 113	GF15.12-P-0001-02B
		Engine 137	GF15.12-P-0001-02L
	ME engine speed signal function		GF07.61-P-3017F
	ETC control unit, location/task	Transmission 722.6	GF27.19-P-4012G