S07.10-0017-79
Block diagram |
A1/1 | Instrument cluster (KI) control unit | N45 | Transfer case (VG) control unit | |
A16 | Knock sensor | N50 | Fuse and relay module control unit (SRM) | |
B2/8 | Hot film mass air flow sensor | N93 | Central gateway (CGW) | |
B6/15 | Intake camshaft position sensor | T1/11 | Cylinder 1 ignition coil | |
B11/17 | Coolant temperature sensor | T1/12 | Cylinder 2 ignition coil | |
B37/4 | Accelerator pedal module | T1/13 | Cylinder 3 ignition coil | |
B70/2 | Crankshaft Hall sensor | T1/14 | Cylinder 4 ignition coil | |
B79/2 | Transmission neutral position position sensor | CAN HMI | User interface CAN | |
G1 | On-board electrical system battery | CAN V | Vehicle CAN | |
G3/2 | Oxygen sensor upstream of catalytic converter | A | Mercedes-Benz | |
M16/6 | Throttle valve actuator | B | Nissan | |
N3/34 | ME-SFI [ME] control unit | C | Default | |
N10/1 | Signal acquisition and actuation module (SAM) control unit | D | Option |
Function requirements for the ignition system, general points
Circuit 87 ON (engine management ON)
Ignition system, general points
Each cylinder is equipped with a directly inserted ignition coil. To control the ignition system, the ME-SFI [ME] control unit reads in the signals from the following sensors and devices:
Intake camshaft position sensor, intake camshaft setting
Crankshaft Hall sensor, engine speed
Hot film mass air flow sensor
Coolant temperature sensor, coolant temperature
Lambda sensor upstream of catalytic converter, residual oxygen
Throttle valve actuator
Knock sensor
Accelerator pedal module, engine load request from driver, accelerator pedal operation fast or slow (when accelerating)
Transmission neutral position position sensor
On-board electrical system battery
Instrument cluster (IC) control unit via central gateway (CGW)
Fuse and relay module control unit (SRM)
During the following conditions, the ME-SFI [ME] control unit revises the ignition timing based on the data stored in the ME-SFI [ME] control unit:
At start
During warm-up
In idle
When battery voltage is low
During acceleration
Function sequence for ignition system
The ignition timing is controlled by the ME-SFI [ME] control unit to maintain the best air/fuel ratio for each engine operating status. The ignition map is stored in the ME-SFI [ME] control unit. The ME-SFI [ME] control unit receives information such as the injection signal and the signal of the intake camshaft position sensor. When this information is processed, the ME-SFI [ME] control unit sends the ignition signals to the respective ignition coil.
If the knock measurement of the knock sensor registers engine knocking, ignition timing is automatically retarded by the ME-SFI [ME] control unit until no more knocking noises are detected.
Operating mode of ignition coil
The relevant ignition coil is, as a rule, charged once per ignition cycle when the desired engine temperature is reached and only 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.
The ignition signal is sent by the ME-SFI [ME] control unit to the power amplifier in the respective ignition coil and amplified. The power amplifier switches the primary circuit of the ignition coil on and off. This induces the correct high voltage level in the secondary circuit.
The flowing secondary current, which depends directly on the charge condition of the ignition coils, is measured in the ignition coils. 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 to generation of a high voltage. This produces a further spark. The following sparks are generated according to the same scheme.