Mercedes-Benz ML320. Manual — part 385



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

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
diagram

Engine 104

GF15.12-P-0001-01D

Engine 111

GF15.12-P-0001-01G

Engine 112

GF15.12-P-0001-01A

Engine 113

GF15.12-P-0001-01B

Engine 119

GF15.12-P-0001-01E

Engine 120

GF15.12-P-0001-01F

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 119, 120

GF15.10-P-3102F

Engine 104, 111

GF15.10-P-3102G

Engine 112, 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 119, 120 (round
connector)

GF07.07-P-4118E

Engine 104, 111, 112,
113, 137

GF07.07-P-4118G

Coolant temperature sensor,
location/task/ design/function

Engine 104, 111

GF07.04-P-5026G

Engine 112, 113, 137

GF07.04-P-5026A

Engine 119, 120

GF07.04-P-5026F

Electronic accelerator,

Engine 104, 111, 112,

GF30.20-P-3010E

2001 Mercedes-Benz ML320

1998-2005 ENGINE Electrical System - Engine - 163 Chassis

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location/design/function

113, 119, 137

Engine 120

GF30.20-P-3010F

Anti-knock control function

GF15.12-P-4024F

Transmission overload protection
function

with automatic
transmission

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 104

GF15.12-P-0001-02D

Engine 111

GF15.12-P-0001-02G

Engine 112

GF15.12-P-0001-02A

Engine 113

GF15.12-P-0001-02B

Engine 119

GF15.12-P-0001-02E

Engine 120

GF15.12-P-0001-02F

Engine 137

GF15.12-P-0001-02L

ME engine speed signal function

GF07.61-P-3017F

ASR V control unit
location/task/design/function

with code 471a
Model 129, 140, 202 as
of 6/94, 170, 208, 210

GF42.40-P-4500A

ESP control unit location / task /
function

with code 472a
Model 129 with engines
104, 119, 120
Model 140
Model 210 with engine
119

GF42.45-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, 113

GF42.45-P-4500B

with code 472a
Model 170 with engines
111, 112
Model 202, 208 with
Engine 111
Model 203

GF42.45-P-4500C

2001 Mercedes-Benz ML320

1998-2005 ENGINE Electrical System - Engine - 163 Chassis

me