Synchronize Fuel Injection And Firing Order Function - GF07.10-S-1006TRJ
Engine 274 in model 447.6/7
with code XM0 (Facelift)
Function requirements synchronization of fuel injection and firing order, general points
- Circuit 87M ON (Engine management ON)
- Engine running.
Synchronization of fuel injection and firing order, general points
The synchronization of the injection sequence and firing order is processed by the ME-SFI [ME] control unit (N3/34) for the actuation of the ignition coils (T1) and fuel injectors (Y62).
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:
- Intake camshaft Hall sensor (B6/29), intake camshaft setting
- Exhaust camshaft Hall sensor (B6/30), exhaust camshaft setting
- Crankshaft Hall sensor (B702), 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 speed signal
Function sequence for synchronization
When starting the engine, the injection sequence is specified to match the firing order. To do this the signals of the crankshaft Hall sensor (B70/2), of intake camshaft Hall sensor (B6/29) and the exhaust camshaft Hall sensor (B6/30) are read in.
Function sequence for engine speed signal
From the signal of the crankshaft Hall sensor (B70/2), the ME-SFI [ME] control unit (N3/34) generates the short-circuit proof engine speed signal (G) (e.g. for cold test and diagnosis) and this is output via the drive CAN (CAN C).
Due to a multipole wheel at the crankshaft with magnetic pole fields with different polarity, a digital signal with a quiescent signal level of 5 V and short-term pulses of 0 V is generated in the crankshaft Hall sensor (B70/2) for a rotating crankshaft. In doing so each individual pole field represents a change of angle of a 6° CKA (crank angle). For the absolute position determination of the crank assembly, a pole field is realized with an interval of 18° CKA.
direction recognition
If the engine rotates backwards, something which can only happen sporadically, briefly before standstill, after the engine has been stopped, then the pulse duration for the 0 V-pulse is altered. The ME-SFI [ME] control unit thus detects a change in the direction of rotation and can thus also precisely detect the position of the crankshaft at any time.
This information is, in particular, needed for rapid starting of the engine using the ECO start/stop function (with code MJ8 (ECO start/stop function)).
If the signal of the crankshaft Hall sensor (B70/2) fails, the signals from the intake camshaft Hall sensor (B6/29) or the exhaust camshaft Hall sensor (B6/30) are used instead.
If the signal of the intake camshaft Hall sensor (B629) fails, alternatively the signal of the exhaust camshaft Hall sensor (B6/30) is used.
If no voltage signal is available from any camshaft Hall sensor, ignition and injection take place after a 360° crank angle in order to allow an emergency engine start.
Top dead center (TDC)
Shown is the synchronization of the injection sequence and firing order
| Function schematic for ME synchronization of fuel injection and firing order | PE07.61-S-2502-97TRH | ||
| Overview of system components for gasoline injection and ignition system with direct injection | GF07.70-S-9998TRJ |