GF07.10-P-1005MMC Ignition System Function

GF07.10-P-1005MMC Ignition System Function
- ENGINES 157.9 in MODEL 216.3, 221.0 /1
- ENGINES 278.9 in MODEL 216.3, 221.0 /1

Function requirements for the ignition system, general points
- Circuit 87M ON (engine control ON)

Ignition system, general points
A single-spark ignition coil is plugged directly into each cylinder. For the ignition system, the ME-SFI (N3/10) control unit reads the following sensors and signals:
- Front knock sensor (left side of engine) (A29/1)
- Rear knock sensor (left side of engine) (A29/2)
- Front knock sensor (right side of engine) (A30/1)
- Rear knock sensor (right side of engine) (A30/2)
- LH and RH intake camshaft Hall sensors (B6/4, B6/5), intake camshaft positions
- LH and RH intake camshaft Hall sensors (B6/6, B6/7), exhaust camshaft positions
- Coolant temperature sensor (B11/4)
- Intake air temperature sensor (B17)
- Pressure sensor downstream of throttle valve actuator (B28/7), engine load
- Crankshaft Hall sensor (B70), engine speed and crankshaft position

The requirements of the torque coordination function are also taken into account.

For the following partial functions, ignition angle adjustment in the direction "retarded" or "advanced" takes place:
- Idle speed control
- Inertia fuel shutoff
- Transmission overload protection
- Knock sensor system
- Torque coordination

Function sequence for ignition system
The ME-SFI [ME] control unit sends the signal for the dwell time of the respective operating point to the ignition coil (T1) over the actuation line (circuit 4). The respective ignition coil interrupts the primary circuit by means of an integral fuse after expiry of the dwell time. The ignition voltage passes from the ignition coil to the spark plug (R4) and causes arcing in the air gap between the center and ground electrodes.

Determination of the ignition angle takes place dependent on a performance map according to the input signals from the ME-SFI [ME] control unit.

Ideal development of the primary and secondary current for a multi-spark ignition







A Dwell time
B Spark duration
C Recharging threshold
D Discharging threshold
E Ignition timing
i1 Primary charging current
i2 Secondary charging current
V Operating voltage

Cylinder arrangement and ignition firing order







1-8 Cylinders 1 to 8
Arrow Direction of travel

Diagnosis
The ignition angles can be checked only with the Diagnosis Assistance System (DAS).