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Fig. 13: Identifying ME-SFI Ignition System Components 
Signal assignment  
 
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Fig. 14: Identifying Signal Assignment - Shown On Engine 119 
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:
EngineRecognition of TDC position of 
cylinderIgnition TDC
1111 and 4Cylinder 1
104, 112, 113, 1191 and 6Cylinder 1
120, 137Right hand cylinder bank: 1 and 6Cylinder 1
 Left cylinder bank: 7 and 12Cylinder 7
 
2001 Mercedes-Benz ML320 
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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 an
y knocking tendency at high intake air and coolant temperatures. The ignition angle is 
 
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"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 torque 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  
 
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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 
diagramEngine 104GF15.12-P-0001-01D
Engine 111GF15.12-P-0001-01G
Engine 112GF15.12-P-0001-01A
Engine 113GF15.12-P-0001-01B
Engine 119GF15.12-P-0001-01E
Engine 120GF15.12-P-0001-01F
 ME-SFI control unit 
position/task/design/ function GF07.61-P-5000F 
 ECI ignition system functionEngine 137GF15.15-P-3000L
 Ignition coils, 
location/task/design/functionEngine 119, 120GF15.10-P-3102F
Engine 104, 111GF15.10-P-3102G
Engine 112, 113GF15.10-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/functionEngine 119, 120 (round 
connector)GF07.07-P-4118E
Engine 104, 111, 112, 
113, 137GF07.07-P-4118G 
 Coolant temperature sensor, 
location/task/ design/functionEngine 104, 111GF07.04-P-5026G
Engine 112, 113, 137GF07.04-P-5026A 
Engine 119, 120GF07.04-P-5026F
 Electronic accelerator, Engine 104, 111, 112, GF30.20-P-3010E 
 
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location/design/function113, 119, 137
  Engine 120GF30.20-P-3010F
 Anti-knock control function GF15.12-P-4024F
 Transmission overload protection 
functionwith automatic 
transmissionGF07.61-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 
assignmentEngine 104GF15.12-P-0001-02D
Engine 111GF15.12-P-0001-02G
Engine 112GF15.12-P-0001-02A
Engine 113GF15.12-P-0001-02B
Engine 119GF15.12-P-0001-02E
Engine 120GF15.12-P-0001-02F
Engine 137GF15.12-P-0001-02L
 ME engine speed signal function GF07.61-P-3017F 
 ASR V control unit 
location/task/design/functionwith code 471a 
Model 129, 140, 202 as 
of 6/94, 170, 208, 210GF42.40-P-4500A
 ESP control unit location / task / 
functionwith code 472a 
Model 129 with engines 
104, 119, 120 
Model 140 
Model 210 with engine 
119GF42.45-P-4500A
with code 472a 
Model 129 with engine 
112, 113 
Model 163 up to 8/02, 
168, 215 
Model 220 (except 
220.08/18) 
Model 202, 208 with 
engine 112, 113 
Model 210 with engine 
111, 112, 113GF42.45-P-4500B 
with code 472a 
Model 170 with engines 
111, 112 
Model 202, 208 with 
Engine 111 
Model 203GF42.45-P-4500C
 
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ANTI-KNOCK CONTROL FUNCTION - GF15.12-P-4024F 
ENGINE 104.941 /943 /944 /991 /994 as of 1.8.96  
ENGINE 104.995  
with CODE (494a) USA version  
with CODE (807) Model year 1997  
with CODE (808) Model year 1998  
with CODE (498) as of Model Year 97 Japanese version  
ENGINE 111.921 /942 as of 1.9.98,  
111.943,  
111.944 as of 1.8.96,  
111.946 as of 1.6.98,  
111.947/973,  
111.975 as of 1.8.96  
ENGINE 111.945  
in MODEL 208.335 /435 as of 1.6.98,  
202.020/080 as of 1.9.98  
ENGINE 111.974  
with CODE (494a) USA version  
with CODE (807) Model year 1997  
with CODE (808) Model year 1998  
ENGINE 111.951 /952 /955 /956 /957 /958 /982 /983  
ENGINE 
Model 211, 230GF42.45-P-4500SL
 ETC control unit, location/taskTransmission 722.6GF27.19-P-4012G 
 
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112.910 /911 /912 /913 /914 /916 /917 /920 /921 /922 /923 /940 /941 /942 /943 /944 /946 /947 /949 /953 /954 /95
ENGINE 113.940 /941 /942 /943 /948 /960 /961 /963 /965 /966 /967 /969  
ENGINE 119.980 /981 /982 /985  
ENGINE 120.982/983  
ENGINE 137.970  
Fig. 15: Identifying Anti
-Knock Control Components - Shown On Engine 119 
Task  
Ensuring knock-free operation of the engine with different fuels in all operating conditions from idling speed up 
to maximum speed of engine, from an engine load of more than approx. 40%. For this purpose, if uncontrolled 
combustion (knocking) occurs, the ignition angle at the relevant cylinder or cylinders is retarded. 
Design/function  
The anti-knock control (AKC) function is integrated in the ME-SFI control unit. The range of functions has 
been enlarged compared to previous versions. 
Input signals: 
Engine speed (crankshaft position sensor) 
 
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