MERCEDES-BENZ ML350 1997 Complete Repair Manual

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

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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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

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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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

2001 Mercedes-Benz ML320
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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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1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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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)

2001 Mercedes-Benz ML320
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Camshaft position (camshaft Hall sensor)
Knock identification:
Engine 104, 111, 112, 113, 119, 120 by means of knock sensors Engine 137 by ionic current
measurement
Engine temperature (coolant temperature sensor)
Engine load (hot film air flow sensor or pressure sensor on supercharged engines)
Accelerator pedal position (accelerator pedal sensor)
Precontrol by means of automatic RON switch (internal)
Output signals:
Cylinder specific ignition angle correction on the calculated map value of the ME control unit.
Ignition angle emergency mode if fault identified.
Basic function
The anti-knock control is active from a coolant temperature of 70 °C. If knocking is detected at a cylinder above
an engine load of approx. 40%, its ignition angle is retarded from the next ignition by about 2.3° crank angle
(e.g. M119) or by about 3.0° crank angle (e.g. M120). If knocking continues to be detected, the ignition angle is
continuously retarded in steps of 2.3° crank angle (e.g. M119) until the maximum retardation is reached
(approx. 10 to 15° crank angle, depending on engine speed). In addition, the automatic RON switch influences
the maximum retarding of the ignition timing - the higher the selected RON stage, the less is the maximum
retarding of the ignition timing.
If knocking-free combustion exists, the retardation is reduced in steps of approx. 0.75° crank angle after a few
ignitions (depending on engine speed) until the map value (a) is achieved, or knocking once again occurs.
Adaptation of anti-knock control
The adaptation of the anti-knock control is active from a coolant temperature of approx. 75 °C. Any corrections
required to the ignition angle because of knocking combustion are constantly detected for the specific cylinder
and stored together with the relevant operating state of the engine (engine load/speed range).
The stored adaptation value is taken into account in the output of the individual cylinder angle so that each
cylinder is immediately operated with the optimal ignition angle.
During abrupt acceleration, no values are stored for about 2 seconds in order to avoid any incorrect adaptation
values.
Faults in the case of knocking detection
If no signals are received from the knock sensors or from the ionic current measurement, the ignition angle of
all the c
ylinders is retarded, for safety reasons, by as much as approx. 11° crank angle depending on engine

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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speed and temperature. The anti-knock control and the adaptation are deactivated and a fault is stored.
Automatic RON switch
In addition to the RON correction using the HHT, the anti-knock control features an automatic RON switch.
This detects a persistent high knocking tendency of the engine and assists the anti-knock control by means of an
appropriate pre-control.
This is done by analyzing the stored adaptation values, the ignition angles of all the cylinders and the number of
control interventions in certain engine load and speed ranges. Depending on the threshold which has been
exceeded, the RON value is adjusted by one or several stages. The value is retained until the engine is switched
off.
After engine start, only the RON correction which is carried out by means of the HHT/STAR DIAGNOSIS is at
first active.
KNOCK SENSORS, LOCATION - GF15.12-P-4101-01A
Crankshaft position sensor,
location/task/ design/function GF07.04-P-4116F
Camshaft Hall sensor,
location/task/design/ function GF07.04-P-4117F
Knock sensors,
location/task/design/function GF15.12-P-4101F
Coolant temperature sensor,
location/task/ design/functionEngine 119, 120GF07.04-P-5026F
Engine 104, 111GF07.04-P-5026G
Engine 112, 113, 137GF07.04-P-5026A
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
Engine 111 EVOGF07.07-P-4118GS
Pedal value sensor,
location/task/design/ function GF30.20-P-4011L
ME-SFI control unit
position/task/design/ function GF07.61-P-5000F
Engine 111 EVOGF07.61-P-5000GS
ME-SFI synchronizing fuel
injection and firing order function GF07.61-P-4009F
Engine 111 EVOGF07.61-P-4009GS

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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Saturday, October 02, 2010 3:18:54 PMPage 24 © 2006 Mitchell Repair Information Company, LLC.

Fig. 16: Identifying Knock Sensors - Engine 112
KNOCK SENSORS, LOCA TION - GF15.12-P-4101-01B
Fig. 17: Identifying Knock Sensors - Engine 113
KNOCK SENSORS, FUNCTION - GF15.12-P-4101-02KE

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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Saturday, October 02, 2010 3:18:54 PMPage 25 © 2006 Mitchell Repair Information Company, LLC.

Fig. 18: Identifying Knock Sensors Oscilloscope Signals
Any vibrations which occur are converted with the aid of the piezo ceramic into electrical signals.
Piezo-electric effect: If a mechanical force acts on a crystal, electrical voltages are produced.

Knock sensor signals may also indicate engine damage, e.g. increased engine noise resulting from a widened
piston groove.
KNOCK SENSORS, LOCATION/TASK/DESIGN/FUNCTION - GF15.12-P-4101F
ENGINE 104.941 /942 /943 /944 /945 /991 /992 /994 /995
ENGINE 111.921 /943 /944 /945 /946 /947 /960 /961 /970 /973 /974 /975 /977
ENGINE 111.942 as of 1.6.96
ENGINE 111.951 /952 /955 /956 /957 /958 /982 /983
ENGINE 119.980 /981 /982 /985
ENGINE 120.982/983
ENGINE

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