Launch X-431 - Page 115

About X-431 Station
Diagnostics
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FAQ
Initial Use
110
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LAUNCH Station
User's Guide
Refer to the instructions for various parts of waveform for the related component working status of specic
waveform section.
Test methods and conditions:
Start the engine or drive the vehicle according to the driving performance fault or poor ignition, etc. Conrm
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.
The waveform shown on Fig. Ignition-4, appears a lot of clutter on the contact break point, which is
obviously caused by the serious erosion on contact break point. It can be veried via burnishing the contact
or changing the circuit breaker.
Fig. Ignition-4
For the primary voltage waveform shown on Fig. Ignition-5, the damped attenuation cycles obviously
reduced on the spark period, the amplitude became lower, which is evidently caused by capacitor leakage.
Fig. Ignition-5
The waveform on Fig. Ignition-6 shows the accidental pumping during contact closing period. The irregular
beating is caused by insufcient spring force.