Synchronize Fuel Injection And Firing Order Function - GF07.10-P-1006MRT
Engine 256.9 in model 213, 238, 257, 290
up to model year 2021
Engine 256.9 in model 222
Function requirements, general
- Engine runs
The ME-SFI [ME] control unit (N3/10) detects the engine running via the evaluation of the crankshaft Hall sensor signals (B70). The ME-SFI [ME] control unit directly reads in the signals of the crankshaft Hall sensor.
Synchronization of fuel injection and firing order, general points
The ME-SFI [ME] control unit synchronizes the injection sequence and firing order.
The ME-SFI [ME] control unit evaluates the signals of the following sensors for the control of the synchronization:
- Intake camshaft Hall sensor (B6/15)
- Exhaust camshaft Hall sensor (B6/16)
- Crankshaft Hall sensor
The ME-SFI [ME] control unit evaluates the input signals and actuates the following components:
- Ignition system
- Cylinder 1 ignition coil (T1/1)
- Cylinder 2 ignition coil (T1/2)
- Cylinder 3 ignition coil (T1/3)
- Cylinder 4 ignition coil (T1/4)
- Cylinder 5 ignition coil (T1/5)
- Cylinder 6 ignition coil (T1/6)
- Fuel system
- Cylinder 1 fuel injector (Y76/1)
- Cylinder 2 fuel injector (Y76/2)
- Cylinder 3 fuel injector (Y76/3)
- Cylinder 4 fuel injector (Y76/4)
- Cylinder 5 fuel injector (Y76/5)
- Cylinder 6 fuel injector (Y76/6)
Synchronization
When starting the engine, the injection sequence is specified to match the firing order. To do this the ignition TDC (Top Dead Center) of cylinder 1 must be recognized.
By the 2nd negative signal edge following the gap in the signal from the crankshaft Hall sensor, the ME-SFI [ME] control unit detects the TDC position of cylinders 1 and 6. If the intake camshaft Hall sensor signal is 0 V (low) at this point in time, ignition TDC of cylinder 1 is regarded as detected.
If the signal of the intake camshaft Hall sensor is missing, the signal of the exhaust camshaft Hall sensor is used as a substitute to detect the ignition TDC of cylinder 1. If no signal is available from the intake camshaft Hall sensor and the exhaust camshaft Hall sensor, injection and ignition takes place after a 360° crank angle in order to thus facilitate an emergency engine start.
Crankshaft angle sensor
On switching off the engine, the crankshaft angle sensor starts; this also detects turning back of the engine just before standstill. During a computer run-on of the ME-SFI [ME] control unit, the determined rest position of the crankshaft is stored in ° crank angle and used for the next engine start. If the crankshaft angle sensor does not lead to any result or the switched-off engine has been turned, the injection sequence and firing order are synchronized during engine start.
Engine speed signal
The engine speed is derived from the crankshaft Hall sensor signal. When the crankshaft is turning, a voltage signal (AC voltage) is generated in the crankshaft Hall sensor by the teeth on the sensor rotor. Here, each tooth generates a voltage pulse. No voltage is generated at the gap where there are 2 missing teeth. The engine speed signal is a square wave signal with a constant duty cycle of 6 pulses (i.e. one per 60° crank angle) per engine revolution and a max. current of approx. 20 mA.
If the crankshaft Hall sensor signal fails, the signals of the intake camshaft Hall sensor or exhaust camshaft Hall sensor are used as a substitute (for the limp-home mode).
| Electrical function schematic, synchronization of the injection and firing order | Engine 256.9 in model 213, 238 up to model year 2021 | PE07.10-P-2706-97DBA | |
| Engine 256.9 in model 222 | PE07.10-P-2706-97SEM | ||
| Engine 256.9 in model 257 up to model year 2021 | PE07.10-P-2706-97XBB | ||
| Overview of system components for gasoline injection and ignition system with direct injection | GF07.70-P-9998MRT |