Operation CHARM: Car repair manuals for everyone.

ME-SFI Synchronizing Fuel Injection and Firing Order Function




ME-SFI Synchronizing Fuel Injection And Firing Order Function




Shown on Engine 119
B6/1 Camshaft Hall sensor
L5 Crankshaft position sensor
N3/10 ME-SFI control unit
T1/1-T1/8 Ignition coils
Y62 Injectors (LH-SFI, HFM-SFI, PEC [LH, HFM, PMS])




a Ignition TDC of cylinder 1
b Output TDC of cylinder 1
c camshaft Hall sensor signal
d Camshaft sprocket with segment
e Crankshaft position sensor signal
f Drive plate with "60-2" teeth

Task
When the engine is started, defining the fuel injection order in line with the firing order on the basis of the signals supplied by the crankshaft position sensor and camshaft Hall sensor. In this way, enabling cylinder-selective cylinder shutoff and knock control system and optimizing emission levels.

Design/function
When the crankshaft is rotating, an alternating voltage is generated in the crankshaft position sensor by the teeth of the driven plate. In this case, each tooth generates an alternating voltage signal.
No voltage is generated as a result of the gap created by 2 missing teeth. The ME-SFI control unit detects the TDC position of cylinder 1 and 6 or cylinder 7 and 12, respectively, with the 2nd negative slope after the gap.

If the signal from the camshaft Hall sensor is still at 0 V ("low") at this moment, the ME-SFI control unit processes this to detect ignition TDC of cylinder 1 and 7, respectively.

Synchronization of the fuel injection and firing order is further processed by the ME-SFI control unit for actuating the ignition coils and the fuel injectors. In addition, it is required for the anti-knock control and for the fuel shutoff at individual cylinders.

Note: If no signal is received from the camshaft Hall sensor, the ME-SFI control unit determines the ignition TDC of cylinder 1 randomly.
Engine 111, 104 start about 1 second later.
Engine 119 starts if ignition TDC of cylinder 1 is determined correctly. Engine may possibly start only at further attempt.

Engine Recognition of TDC Recognition of ignition
position of cylinder TDC of cylinder
111 1 and 4 1
119,104,112,113 1 and 6 1
120 Right cylinder bank: 1 and 6 Right cylinder bank: 1
Left cylinder bank: 7 and 12 Left cylinder bank: 7
137 1 and 7 Cylinder 1 (signal of camshaft Hall sensor right bank of cylinders "low" )