Chrysler laser 1990 Technical Information Manual page 81

No. 1 TDC
,
angle si g nal
Crank
No. 1 cylinder
Intake
No. 3 cyltnder
stroke
No. 4 cylinder
,
No. 2 cylinder tlon
stroke
Crank 1
ELECTRICAL - Engine Electrical
No. 3 TDC
I
I
Combustion
stroke
Compression
stroke
Intake
stroke
The cylinder to be ignited is determined based on the top dead
center signal and the crank angle signal.
engine control unit when the crank angle signal is input, the
unit decides that the No. 1 cylinder (or No. 4) cylinder is on the
compression stroke and turns off power transistor "A" and
causes the No. 1 cylinder (and No.4 cylinder) to fire.
If the top dead center signal has not been input to the engine
control unit when the crank angle signal is input, the unit
decides that the No.3 cylinder (or No. 2) cylinder is on the
compression stroke and turns off power transistor "B" and
causes the No.3 cylinder (and No. 2 cylinder) to fire. In this way,
the power transistors "A" and "B" are turned off alternately for
ignition power distribution.
Ignition Timing Control
The period (T) of the crank angle signal is measured and based
on this v&lue, the time (t) taken for the crank to make a
revolution is determined.
I
Once t is determined, the ignition timing (T,) is calculated using
the t value and the ignition advance angle (advance from TDC)
determined by the engine control unit, with the 75"BTDC Signal
as a reference; then the primary current shut-off signal is Sent
to the power transistor when T, time has elapsed from the
count start position (75"BTDC).
where 8 is the ignition advance
No 4TDC
Exhaust
stroke
Exhaust
stroke
. stroke
Compression
stroke
intake
stroke stroke
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8-29
No 2 TDC
Intake
stroke
Exhaust
stroke
angle calculated by the engine