CAC Gasoline Engine Maintenance And Servicing Manual
90
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.
the following is for checking primary coil and secondary coil resistance.
R1=0.55Ω+/-10% (20℃) R2=7400Ω+/-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
—— during acceleration and deceleration shut
—— when shutten off
—— during over speeding
during idling, the engine rpm is 900±50r/min,and ignition advance is 10°±1°(Engine is already
warmed and with no electrical load).
Fig. 149 high pressure coil of electrostatic distribution
two-way select switch
coil
relay
signal
Spark plug
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