LAUNCH X431 GDS Scopebox Manual
Ignition line:
Observe the height consistence of flashover voltage. Too high
flashover voltage (even out of t
he 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
represe
nts the consiste
nce 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.
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