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5. Ignition advance calculation and high voltage distribution
The system uses two high tension ignition coils and assigns ignition voltages directly to spark plugs by
static electricity (distributorless ignition) directly. Connector and controlling triode are comprised in the
ECU injection system and connected to ECU connector 1 and connector 19 . (figure. 175).
When ECU microprocessor identifies the signals of two tooth-missed signals, it will begin to count
tooth. Cylinder 1 or cylinder 4 TDC comes after 20 teeth are counted. Cylinder 2 or cylinder 3 TDC comes
after 50 teeth are counted (determine by pair).
ECU calculate the primary coil conductivity of cylinder 1, 4 or cylinder 2, 3 and ignition advance
according to the gained parameters (pressure, rpm) and calculate the dynamic compensation according to
the engine working condition.
Fig.175
The following is for checking primary coil and secondary coil resistance. R1=0.55
Ω
+/-
10% (20
℃
) R2=7400
Ω
+/-10% (20
℃
)
The base ignition advance value in the chart is determined after several adjustments according to the
coolant temperature and air temperature. One filter restricts the change of two continuous TDCs, Under a
specified condition, ignition advance will be compensated dynamically.
Base ignition advance value, as a function of manifold absolute pressure and engine speed, is inserted
into two-dimension diagram.
At a rather low speed, ignition advance remains fixed. The positive and negative change of ignition
advance between two continuous TDCs is limited by two calibration values.
The dynamic compensating of ignition advance occurs under the following conditions:
—— During idling or running without rpm fluctuations
