Synchronize Fuel Injection And Firing Order Function - GF07.10-S-1006TRC
Engine 274 in model 447, 448
except code XM0 (Facelift)
Function requirements synchronization of fuel injection and firing order, general points
- Circuit 87M ON (Engine management ON)
- Engine runs
Synchronization of fuel injection and firing order, general points
Synchronization of the injection and firing order is processed by the ME-SFI [ME] control unit (N3/34) in order to actuate 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 [ME] control unit (N3/34) 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 short-circuit proof engine speed signal (G) (e.g. for the cold test and diagnosis) is generated by the ME-SFI [ME] control unit (N3/34) and is issued via the drive train CAN (CAN C).
A multi pole wheel on the crankshaft with magnetic pole fields of a different polarity generates a digital signal with a quiescent signal level of 5 V and short-term pulses of 0 V in the crankshaft Hall sensor (B70/2) for a turning crankshaft. In doing so each individual pole field represents a change of angle of a 6° CKA (crank angle). To absolutely determine the position of the crank assembly, a pole field is configured with a distance 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 (N3/34) can thereby determine any change in direction of rotation and thus record the exact angular position of the crankshaft at any given 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.
| Electrical function schematic, synchronization of the injection and firing order | Engine 274 in model 448 except code XM0 (Facelift) |
PE07.10-S-2706-97VDC | |
| Engine 274 in model 447 except code XM0 (Facelift) |
PE07.10-S-2706-97TRC | ||
| Overview of system components for gasoline injection and ignition system with direct injection | GF07.70-S-9998TRC |