Page 758 of 1449

ENGINE ELECTRICAL -Ignition System16-26
IGNITION SYSTEM
GENERAL INFORMATION
This system is equipped with two ignition coils (A
and B) with built-in power transistors for the No.
1 and No. 4 cylinders and the No. 2 and No. 3
cylinders respectively.
Interruption of the primary current flowing in the
primary side of ignition coil A generates a high
voltage in the secondary side of ignition coil A.
The high voltage thus generated is applied to the
spark plugs of No. 1 and No. 4 cylinders to generate
sparks. At the time that the sparks are generated
at both spark plugs, if one cylinder is at the
compression stroke, the other cylinder is at the
exhaust stroke, so that ignition of the compressed
air/fuel mixture occurs only for the cylinder which
is at the compression stroke.
In the same way, when the primary current flowing
in ignition coil B is interrupted, the high voltage
thus generated is applied to the spark plugs of
No. 2 and No. 3 cylinders.
The Engine-ECU turns the two power transistors
inside the ignition coils alternately on and off. Thiscauses the primary currents in the ignition coils
to be alternately interrupted and allowed to flow
to fire the cylinders in the order 1-3-4-2.
The Engine-ECU determines which ignition coil
should be controlled by means of the signals from
the camshaft position sensor which is incorporated
in the camshaft and from the crank angle sensor
which is incorporated in the crankshaft. It also
detects the crankshaft position in order to provide
ignition at the most appropriate timing in response
to the engine operation conditions. It also detects
the crankshaft position in order to provide ignition
at the most appropriate timing in response to the
engine operation conditions.
When the engine is cold or operated at high
altitudes, the ignition timing is slightly advanced
to provide optimum performance.
When the automatic transmission shifts gears, the
ignition timing is also retarded in order to reduce
output torque, thereby alleviating shifting shocks.
SYSTEM DIAGRAM
Barometric pressure sensor
Intake air temperature sensor
Engine coolant temperature sensor
Camshaft position sensor
Crank angle sensor
Ignition switch - ST
Vehicle speed signalEngine-ECU
Ignition coil A
Ignition coil B Ignition switch
Spark plugBattery
To tachometerCylinder No. Air flow sensor
1 4
23
Detonation sensor
Page 759 of 1449
ENGINE ELECTRICAL -Ignition System16-27
IGNITION COIL SPECIFICATIONS
ItemsSpecifications
TypeMolded 2-coil
SPARK PLUG SPECIFICATIONS
ItemsSpecifications
NGKIGR7A-G
DENSOVW22PR-DA7
SERVICE SPECIFICATIONS
IGNITION COIL
ItemsStandard value
Secondary coil resistance kΩ8.5 - 11.5
SPARK PLUG
ItemsStandard valueLimit
Spark plug gap mm0.6 - 0.70.75
RESISTIVE CORD
ItemsLimit
Resistance kΩmax. 22
SPECIAL TOOL
ToolNumberNameUse
MD998773Detonation sensor
wrenchDetonation sensor removal and installation
Page 760 of 1449
ENGINE ELECTRICAL -Ignition System16-28
ON-VEHICLE SERVICE
IGNITION COIL (WITH BUILT-IN POWER
TRANSISTOR) CHECK
Check by the following procedure, and replace if there is
a malfunction.
SECONDARY COIL RESISTANCE CHECK
Measure the resistance between the high-voltage terminals
of the ignition coil.
Standard value: 8.5 - 11.5 kΩ
PRIMARY COIL AND POWER TRANSISTOR
CONTINUITY CHECK
NOTE
1. An analogue-type circuit tester should be used.
2. Connect the negative ( - ) prove of the circuit tester to
terminal 1.
Caution
This test must be performed quickly (in less than 10
seconds) to prevent coil from burning and power
transistor from breakage.
1.5V power across 2 - 3Continuity across 1 - 2
When energizedYe s
When not energizedNo
RESISTIVE CORD CHECK
Measure the resistance of the all spark plug cables.
1. Check cap and coating for cracks.
2. Measure resistance.
Limit: Max. 22 kΩ
Page 761 of 1449

ENGINE ELECTRICAL -Ignition System16-29
SPARK PLUG CHECK, CLEANING AND REPLACEMENT
SPARK PLUG GAP CHECK
Caution
1. Do not adjust the gap of the iridium plug.
2. Cleaning of the iridium plug could damage the tip of the electrode. Thus, if the plug must
be cleaned because of soot, etc., use a plug cleaner and clean within a short time of 20 seconds
or less to protect the electrode. Do not use a wire brush, etc.
3. Even when the functions of the iridium plug are normal, the electrode section may be blackened.
However, the adhered carbon has properties that easily burned off compared to the conventional
type, so there is no problem. Check the quality of the spark plug by checking the insulation
resistance.
Check the plug gap, and replace if the checked value is more than the limit value.
Standard value, limit value:
MakerModelStandard value (mm)Limit value (mm)
NGKIGR7A-G0.6 - 0.70.75
DENSOVW22PR-DA70.6 - 0.70.75
SPARK PLUG INSULATION RESISTANCE CHECK
Measure the insulation resistance of the spark plug, and
replace if the measured value is less than the limit value.
Limit value: 1 MΩ
CAMSHAFT POSITION SENSOR CHECK
Refer to GROUP 13A - Troubleshooting.
CRANK ANGLE SENSOR CHECK
Refer to GROUP 13A - Troubleshooting.
DETONATION SENSOR CHECK
Check the detonation sensor circuit if self-diagnosis code,
No. 31 is shown.
NOTE
For information concerning the self-diagnosis codes, refer
to GROUP 13A - Troubleshooting.
Page 762 of 1449

ENGINE ELECTRICAL -Ignition System16-30
WAVEFORM CHECK USING AN ANALYZER
Ignition Secondary Voltage Waveform Check
MEASUREMENT METHOD
1. Clamp the secondary pickup around the spark plug cable.
NOTE
(1) The peak ignition voltage will be reversed when the
spark cables No. 2 and No. 4, or No. 1 and No.
3 cylinders are clamped.
(2) Because of the two-cylinder simultaneous ignition
system, the waveforms for two cylinders in each group
appear during waveform observation (No. 1 cylinder
- No. 4 cylinder, No. 2 cylinder - No. 3 cylinder).
However, waveform observation is only applicable
for the cylinder with the spark plug cable clamped
by the secondary pickup.
(3) Identifying which cylinder waveform is displayed can
be difficult. For reference, remember that the
waveform of the cylinder attached to the secondary
pickup will be displayed as stable.
2. Clamp the spark plug cable with the trigger pickup.
NOTE
Clamp the trigger pickup to the same spark plug cable
clamped by the secondary pickup.
Page 763 of 1449
ENGINE ELECTRICAL -Ignition System16-31
STANDARD WAVEFORM
Observation Conditions
FunctionSecondary
Pattern heightHigh (or Low)
Pattern selectorRaster
Engine revolutionsCurb idle speed
kV
Secondary
ignition
voltage
waveformIgnition voltage
(point D)
Dwell
section
Point CSpark line (point A)
Wave damping
reduction section
(point B)
Time
Observation Condition (The only change from above condition is the pattern selector.)
Pattern selectorDisplay
Secondary
ignition
voltage
waveformkV
No. 4 cylinder
No. 2 cylinder
ignition noiseNo. 1 cylinderNo. 3 cylinder
ignition noise
Neutral section 0
2Time
Page 764 of 1449

ENGINE ELECTRICAL -Ignition System16-32
WAVEFORM OBSERVATION POINTS
Point A: The height, length and slope of the spark line show the following trends (Refer to abnormal
waveform examples, 1, 2, 3 and 4).
Spark linePlug gapCondition of
electrodeCompression
forceConcentration of
air mixtureIgnition timingSpark plug
cable
LengthLongSmallNormalLowRichAdvancedLeak
ShortLargeLarge wearHighLeanRetardedHigh
resistance
HeightHighLargeLarge wearHighLeanRetardedHigh
resistance
LowSmallNormalLowRichAdvancedLeak
SlopeLargePlug is fouled----
Point B: Number of vibration in reduction vibration section (Refer to abnormal waveform example 5)
Number of vibrationsCoil and condenser
Three or moreNormal
Except aboveAbnormal
Point C: Number of vibrations at beginning of dwell section (Refer to abnormal waveform example 5)
Number of vibrationsCoil
5 - 6 or higherNormal
Except aboveAbnormal
Point D: Ignition voltage height (distribution per each cylinder) shows the following trends.
Ignition
voltagePlug gapCondition of
electrodeCompression
forceConcentration of
air mixtureIgnition timingSpark plug cable
HighLargeLarge wearHighLeanRetardedHigh resistance
LowSmallNormalLowRichAdvancedLeak
Page 765 of 1449
ENGINE ELECTRICAL -Ignition System16-33
EXAMPLES OF ABNORMAL WAVEFORMS
Abnormal waveformWave characteristicsCause of problem
Example 1
01P0215
Spark line is high and short.Spark plug gap is too large.
Example 2Spark line is low and long, and is
sloping.
Also, the second half of the spark line
is distorted. This could be a result of
misfiring.Spark plug gap is too small.
Example 3Spark line is low and long, and is
sloping. However, there is almost no
spark line distortion.Spark plug gap is fouled.
Example 4Spark line is high and short.
Difficult to distinguish between this
and abnormal waveform example 1.Spark plug cable is nearly falling off.
(Causing a dual ignition)
Example 5No waves in wave damping section.Layer short in ignition coil