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Using Oscilloscopes on Vehicles

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 Author| Post time 2018-1-9 14:18:02 | Show all posts
1 Secondary standard waveform analysis

Secondary coil of the secondary ignition waveform is shown in figure 1, each point analysis is as follows:

Secondary Ignition Standard Waveform
Point a: Primary coil turn on (The current increasing is slow when primary coil turn on, thus the electromotive
force generated from secondary coil is slow as well, and its direction is opposite.)

Point b: Primary coil current reached the point of saturation (i.e. turn on the primary coil, when current rised upto
the point of constant current value, the constant current function of ignition controller start to work.

Section a - b: The primary coil switch-on, current increases until the ignition controller starts the constant current
control process (build the magnetic field energy).


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 Author| Post time 2018-1-10 08:51:51 | Show all posts
Section a - b: The primary coil switch-on, current increases until the ignition controller starts the constant current control
process (build the magnetic field energy).

Point c: The moment of primary coil power-off (ignition controller controls primary coil power-off and starts to ignition).

Section b - c: constant current control section (the holding constant current section when primary coil current rose to the
ignition controller constant current ). Constant current: indicates the ignition primary coil charging current rises to a certain
amperage and stabilizes the charging to coil.


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 Author| Post time 2018-1-11 10:52:35 | Show all posts
Section a - c: closing angle (primary coil energization time from primary coil on to the ignition). Generally, 4 cylinders engine
closing angle is 45% - 60%, i.e. calculated according to the camshaft angle is 90 x (45 ~ 60)%; and calculated according to
the crank angle is 180 x (45 ~ 60)%, which means that the closing angle time is one cylinder complete a work cycle, the
camshaft angle is 90 degrees, and the crankshaft rotation angle is 180 degrees, and in the entire working cycle, the ratio
is 45% to 60% of the angle. But 6-cylinder engine closing angle is 60% - 70%.



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 Author| Post time 2018-1-12 13:39:09 | Show all posts
Point d: Breakdown high voltage generated by the secondary coil at the moment of primary power failure
breaks down the highest voltage point of the spark plug gap, immediately dropping once the spark plug
gap has been broken. The breakdown voltage is affected by many factors, such as spark plug gap, spark
plug electrode shape, mixture concentration, cylinder pressure, cylinder compression temperature and
so on.

The larger the spark plug electrode gap, the sharper the electrode shape, the higher the breakdown voltage
and the greater ignition energy required. Mixture is too thick, because HC and air molecules are compressed
and squeeze intensive, high pressure to make it more difficult for positive and negative electron separation,
the need for greater voltage to make it ionized to form an electron flow spark. Mixture is too thin, HC and air
molecules are relatively thin, the molecules can not be ionized at the same time, so that the higher the ionization
voltage can penetrate the slender gap. The higher the temperature, the more active molecules, ionization easier,
the required breakdown voltage is low, on the contrary the required voltage is high. Only moderate gas mixture, oil
and gas molecules are evenly distributed, the electrode generates electron flow is relatively easy, the breakdown
voltage at this time is the standard voltage.


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 Author| Post time 2018-1-15 08:43:20 | Show all posts
Point e: the starting point of spark formation (i.e. the moment when the high voltage breaks down the gap of the
spark plug to form the electron current, the conversion of thermal energy started).

Section c - f: capacitor discharge section (equivalent to a large capacitor discharge, spark formation process,
that is, the formation of electron flow breakdown ionization process).

Point g: the end point of spark (i.e. the lowest energy point of the magnetic energy conversion last until cannot
keep the electron current when breakdown form the electron current ).


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 Author| Post time 2018-1-16 08:28:29 | Show all posts
Section f - g: the duration of the spark, also known as the burning line, that is, the duration of the electron current after
the breakdown of electrode. The voltage is the spark burning voltage, is the voltage to maintain the spark transfer. Generally,
it’s 1/ 4 of the breakdown voltage. This section also called inductance discharge section. This section should be relatively flat,
clean and non-abnormal waveforms.

Section h - i: winding coil normal attenuation oscillation part: usually there are more than 3 oscillation waveforms, and standard
is 5 to 6 waveforms. That is after the magnetic energy conversion electric energy can not maintain the spark conduction, the
magnetic energy of the primary coil and the secondary coil decay and disappear from each other. If the attenuation wave is
too little, the performance of the coil is degraded.


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 Author| Post time 2018-2-1 13:05:49 | Show all posts
Secondary coil waveform analysis principle: When igniting, the secondary coil generates a high voltage,
when the voltage gradually up to a certain value, the spark plug spark (In the test, the spark energy show
a blue-white flame, and last 1. 5 ~ 2. 4 ms (distributor system). In the non-distributor ignition system,
the standard spark time must be above 0. 8 ~ 1. 8ms. Such a flame in the cylinder owns high energy,
fast propagation, the rapid combustion within the cylinder Full, explosive pressure, engine power output
high), this voltage is the ignition voltage. Then the voltage drops rapidly to another voltage value and
maintain a period of time, the voltage is the combustion voltage, the combustion time is the voltage is
maintained at the combustion voltage value of the time. At the end of the burning time, the energy in the
ignition coil is basically exhausted, and the residual energy forms damped oscillation on the coil.
The number of oscillation waves is required to be more than 3 (standard 5 to 6).


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 Author| Post time 2018-2-3 11:18:08 | Show all posts
Secondary coil waveform analysis principle: When the ignition, the secondary coil produces a high voltage,
when the voltage gradually increases to a certain value, the spark plug spark (test spark energy performance
for the blue-white flame, and can continue 1. 5 ~ 2.4 ms (distributor system), in the absence of distributor
ignition system, the standard spark time must be 0. 8 ~ 1. 8ms or more.


This flame in the cylinder of high energy, fast propagation, the rapid combustion of the cylinder full, explosive
pressure, the engine power output high), this voltage is the ignition voltage. Then the voltage drops rapidly to
another voltage value and maintain a period of time, the voltage is the combustion voltage, the combustion
time is the voltage is maintained at the combustion voltage value of the time. At the end of the burning time,
the energy in the ignition coil is basically exhausted, and the residual energy forms damped oscillation on the
coil. The number of oscillation waves is required to be more than 3 (standard 5 to 6).

Ideally, the secondary waveform is very stable, indicating that the voltage at each ignition firing is the same.
The graphics of each cylinder should be roughly the same. However, the actual situation is not ideal, the graphics
will always have larger or smaller jitter, such as ignition or breakdown voltage fluctuated, burning time may vary,
these do not necessarily indicate that the engine is faulty. This third Gao Lu and: secondary ignition waveform in
the application of fault diagnosis 7 will require our accumulated experience, combined with other test data
comprehensive analysis.


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 Author| Post time 2018-2-5 16:14:10 | Show all posts
2 secondary ignition waveform fault point analysis
The measured engine ignition waveform display, the first should be with the standard wave
Shape control. If the measured ignition waveform exactly the same as the standard waveform, said
Ming fire system technical condition is good; if the measured waveform is abnormal, that
Ignition system or other system fault, should be different according to the ignition waveform
Failure to reflect the area, diagnosed the cause of the malfunction.
2. 1 ignition coil charging part
Observe that the ignition coil remains relatively constant at the beginning of charging
The falling edge of the waveform indicates the consistent closing angle and ignition of each cylinder
When accurate, if not coincidental, ultra-poor too much to prove that the super-poor cylinder ignition line
Circle controller bad ground or performance degradation. If the falling edge is a slope,
Then the controller power tube performance degradation or poor grounding; view
Whether the closed angle of each cylinder can be consistent; check the closing angle of the large
Small whether the engine operating conditions the size of the correct adjustment.


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 Author| Post time 2018-2-5 16:15:24 | Show all posts
2 Secondary ignition waveform fault point analysis

The measured engine ignition waveform display, the first should be with the standard wave
Shape control. If the measured ignition waveform exactly the same as the standard waveform, said
Ming fire system technical condition is good; if the measured waveform is abnormal, that
Ignition system or other system fault, should be different according to the ignition waveform
Failure to reflect the area, diagnosed the cause of the malfunction.


2. 1 Ignition coil charging part
Observe that the ignition coil remains relatively constant at the beginning of charging
The falling edge of the waveform indicates the consistent closing angle and ignition of each cylinder
When accurate, if not coincidental, ultra-poor too much to prove that the super-poor cylinder ignition line
Circle controller bad ground or performance degradation. If the falling edge is a slope,
Then the controller power tube performance degradation or poor grounding; view
Whether the closed angle of each cylinder can be consistent; check the closing angle of the large
Small whether the engine operating conditions the size of the correct adjustment.


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