Launch X-431 PAD III Manual page 133

LAUNCH X-431 PAD III User Manual
poor ignition, etc. Confirm the consistence of judgment standard (the amplitude,
frequency, shape and pulse width, etc., for each cylinder), check the fault of the
waveform for corresponding components.
Waveform results: observe the ignition coil at the beginning of charging, the
relative consistent falling edge represents the dwell angle and ignition timing of
each cylinder are precise.
Ignition line:
Observe the height consistence of flashover voltage. Too high flashover voltage
(even out of the oscilloscope screen) represents a high resistance existed in the
ignition secondary circuit (for example, open circuit, or damaged spark plug or
high voltage line, or too large time gap on spark plug), while the too short
sparking voltage represents the resistance of ignition secondary circuit is lower
than normal value (due to pollutant and broken spark plug or the high voltage
line of spark plug has electrical leakage, etc.).
Spark or combustion voltage:
Observe the consistence of spark or combustion voltage, as it represents the
consistence of spark plug and the air-fuel ratio of each cylinder. In case that the
mixing ratio is too lean, the combustion voltage will be lower than normal value.
Combustion line:
Observe the spark or the combustion line which shall be clean with few clutter,
as lots of clutter indicates the cylinder has poor ignition due to ignite too early,
damaged nozzle, pollutant spark plug, or other reasons. The duration of
combustion line indicates the mixing ratio of the cylinder is abnormal lean or rich.
Too long combustion line (usually greater than 2ms) represents the mixing ratio
is rich, whereas too short of combustion line (usually less than 0.75ms)
represents the mixing ratio is lean.
Ignition coil oscillation:
Observe at least two oscillation waveforms after the combustion line, which will
be better if more than three oscillation waveforms, as it represents the ignition
coil and capacitor (on Platinum or ignition system) are normal.
Primary voltage analysis
According to the faulty primary voltage waveform collected by the ignition
analysis, the related components and mechanical equipment status of ignition
system electrical circuit can be analyzed, which provides a reliable basis for the
adjustment and maintenance of power circuit to avoid the blind demolition.
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