Mitsubishi Space Star. Manual - part 98

ENGINE ELECTRICAL – 

Ignition System

16-11

IGNITION FAILURE SENSOR CHECK

NOTE
An analog-type circuit tester should be used.

Check that the resistance between terminals 3 and 4 is at
the standard value.

Standard value: 0.1 

Ω

 or less

WAVEFORM CHECK USING AN ANALYZER
<4G13-MPI>
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.

ENGINE ELECTRICAL – 

Ignition System

16-12

STANDARD WAVEFORM

Observation Conditions

Function

Secondary

Pattern height

High (or Low)

Pattern selector

Raster

Engine revolutions

Curb idle speed

kV

Secondary
ignition
voltage
waveform

Ignition voltage
(point D)

Dwell
section

Point C

Spark line (point A)

Wave damping 
reduction section
(point B)

Time

Observation Condition (The only change from above condition is the pattern selector.)

Pattern selector

Display

Secondary
ignition
voltage
waveform

kV

No. 4 cylinder

No. 2 cylinder
ignition noise

No. 1 cylinder

No. 3 cylin-
der ignition
noise

Neutral section

0

2

Time

ENGINE ELECTRICAL – 

Ignition System

16-13

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 line

Plug gap

Condition of
electrode

Compression
force

Concentration of
air mixture

Ignition timing

Spark plug
cable

Length

Long

Small

Normal

Low

Rich

Advanced

Leak

Short

Large

Large wear

High

Lean

Retarded

High 
resistance

Height

High

Large

Large wear

High

Lean

Retarded

High 
resistance

Low

Small

Normal

Low

Rich

Advanced

Leak

Slope

Large

Plug is fouled

–

–

–

–

Point B: Number of vibration in reduction vibration section (Refer to abnormal waveform example 5).

Number of vibrations

Coil and condenser

Three or more

Normal

Except above

Abnormal

Point C: Number of vibrations at beginning of dwell section (Refer to abnormal waveform example 5).

Number of vibrations

Coil

5 – 6 or higher

Normal

Except above

Abnormal

Point D: Ignition voltage height (distribution per each cylinder) shows the following trends.

Ignition
voltage

Plug gap

Condition of
electrode

Compression
force

Concentration of
air mixture

Ignition timing

Spark plug cable

High

Large

Large wear

High

Lean

Retarded

High resistance

Low

Small

Normal

Low

Rich

Advanced

Leak

ENGINE ELECTRICAL – 

Ignition System

16-14

EXAMPLES OF ABNORMAL WAVEFORMS

Abnormal waveform

Wave characteristics

Cause of problem

Example 1

01P0215

Spark line is high and short.

Spark plug gap is too large.

Example 2

Spark 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 3

Spark line is low and long, and is
sloping. However, there is almost no
spark line distortion.

Spark plug gap is fouled.

Example 4

Spark 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 5

No waves in wave damping section.

Rayer short in ignition coil.