Synchronize Fuel Injection And Firing Order Function - GF07.10-P-1006MNF
Engine 176.9 in model 463
as of model year 2016 up to model year 2019
Function requirements synchronization of fuel injection and firing order, general points
- Circuit 87M (Engine management ON)
- Engine runs
The circuit relay 87M(F58kN) is switched on for circuit 15 ON.
Synchronization of fuel injection and firing order, general points
Synchronization of the injection and firing order is achieved by the ME-SFI control unit (N3/10) for actuation of the ignition coils (cylinder 1 + 2 ignition coil to cylinder 7 + 8 ignition coil (T4 toT4/3) and the cylinder 1 to 8 fuel injectors (Y76/1 to Y76/8)).
Furthermore, synchronization is required for knock control and fuel shutoff on the individual cylinders.
The ME-SFI control unit synchronizes the injection and firing order using the signals from the following sensors:
- Left intake camshaft Hall sensor (B6/4) and right intake camshaft Hall sensor (B6/5), intake camshaft positions
- Left exhaust camshaft Hall sensor (B6/6) and right exhaust camshaft Hall sensor (B6/7), exhaust camshaft positions
- Crankshaft Hall sensor (B70), engine speed and crankshaft position
Function sequence for synchronization of the fuel injection and firing order
The function sequence is described in the following steps:
- Function sequence for synchronization
- Function sequence for engine coasting detection
- Function sequence for engine speed signal
Function sequence for synchronization
When the engine is started, the injection sequence is determined in accordance with the firing order using the voltage signals from the crankshaft Hall sensor and the intake camshaft or exhaust camshaft Hall sensors. To do this the ignition TDC (Top Dead Center) of cylinder 1 must be recognized.
At the second negative signal edge following the gap in the signal from the crankshaft Hall sensor, the ME-SFI control unit detects the TDC position in cylinders 1 and 6. If the signal from an intake camshaft Hall sensor is at 0 V (low) at this time, the ME-SFI control unit processes it to detect ignition TDC in cylinder 1.
If the voltage signal from a camshaft Hall sensor is missing, the voltage signal from another camshaft Hall sensor is taken in a certain sequence and used as a replacement to detect ignition TDC in cylinder 1. If no voltage signal whatsoever is available from a camshaft Hall sensor, injection and ignition take place after a 360° CKA (Crank Angle) in order to allow an emergency engine start.
Function sequence for engine coasting detection
When the engine is stopped, engine coasting detection is started, which also evaluates the engine turn back shortly before standstill. During a computer run on from the ME-SFI control unit, the determined rest position of the crankshaft as a °CKA is stored and used for the next engine start. If engine coasting detection does not produce a result or the engine has been turned while shut down, injection and firing order are synchronized at engine start.
Function sequence for engine speed signal
Using the signal from the crankshaft position sensor, the ME-SFI control unit generates the engine speed signal (for example for cold testing and diagnosis) and outputs it via the drive CAN (CAN C) to the powertrain control unit (N127).
A voltage signal (AC voltage) is generated in the crankshaft Hall sensor by the teeth on the sensor rotor (perforated plate) when the crankshaft is turning. Here, each tooth generates a voltage pulse. No voltage signal is generated at the gaps where there are missing stays. The engine speed signal is a square wave signal with a constant on/off ratio of six pulses per engine revolution (60° CKA) and a maximum current of approx. 20 mA.
If the voltage signal from the crankshaft Hall sensor drops, the voltage signals from the left and right intake camshaft Hall sensors or the left and right exhaust camshaft Hall sensors are used instead (in limp-home mode).
Signal assignment
| Electrical function schematic, synchronization of the injection and firing order | PE07.10-P-2706-97ZGD | ||
| Overview of system components for gasoline injection and ignition system with direct injection | GF07.70-P-9998MNF |