Ignition system function - GF07.10-P-1005MMO
ENGINE 276.9 in MODEL 212.095 up to model year 2014
Function requirements for the ignition system, general points
- Circuit 87M (engine timing ON)
Ignition system, general points
Each cylinder is equipped with a directly inserted ignition coil (T1). The ME-SFI [ME control unit (N310) reads in the following sensors and signals for the ignition system:
- Right knock sensor (A16/1)
- Left knock sensor (A16/2)
- Left and right intake camshaft Hall sensors (B6/4, B6/5), intake camshaft positions
- Left and right exhaust camshaft Hall sensors (B6/6, B6/7), exhaust camshaft positions
- Coolant temperature sensor (B11/4)
- Intake air temperature sensor (B17)
- Intake manifold intake air temperature sensor (B17/1)
- Pressure sensor downstream of throttle valve (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
- Deceleration fuel shutoff
- Transmission overload protection
- Knock control
- 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 over the actuation line (circuit 4). The respective ignition coil interrupts the primary circuit by means of an integral fuse after expiration 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 characteristics map according to the input signals from the ME-SFI [ME] control unit.
Operating mode for the ignition coil
Single spark ignition
The ignition coil is usually charged for an engine running at its normal operating temperature once per ignition cycle and an ignition spark is generated. Ignition coils with high energies can be used to securely ignite the mixture, also in cold start conditions, which allow a long spark ignition period.
There is also the option to use many sparks instead of just one per ignition process. This operating mode is called Multispark mode.
Multi-spark ignition
In contrast to single spark mode many sparks are used in Multispark mode. This is not a series of a number of single sparks occurring one after the other but instead the ignition coil is recharged in-between in order to again provide sufficient energy for sparks. Multispark ignition begins like a single spark ignition. The ignition coil is supercharged at the beginning up to a desired target primary current. The charging current is switched off at the ignition timing whereby the ignition spark is created. However, the ignition coil is not completely discharged in Multispark mode.
The flowing secondary current which directly depends on the charge level of the ignition coil is measured in the ignition coil. If it drops below the secondary current threshold, the coil electronics switches the power amplifier to conducting again, whereby the charging current flows again.
The level of the flowing primary current is also monitored. If the primary current threshold is reached, the power amplifier closes the primary circuit and it comes again into high voltage generation mode. This produces a further spark. The following sparks are generated according to the same scheme.
Ideal development of the primary and secondary current for a multi-spark ignition
Diagnosis
The ignition angles can be checked using the Xentry diagnostics.
Engine configuration and ignition firing order
| Electrical function schematic for ignition system | PE07.10-P-2705-97DAI | ||
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