WS8

Primary & Secondary Ignition Patterns

WS8 Primary & Secondary Ignition Pattren
Make & Model : Toyota 4A - FE engine

Firing voltage : The voltage needed to push the spark jumps to the spark plug gap.

Burn voltage : The voltage needed to maintain the ARC between the spark plug electrodes to burn all the fuel in the combustion chamber.

Burn time : The length of time during which the ARC is maintained between the spark plug electrodes.

Normally used to check the secondary circuit components.Like  spark plugs , HT leads , secondary ignition coil, distributor cap,rotor and king lead.

Dwell time : The length of time during which the primary circuit is grounded,turned on before each cylinder firing so that it can build strong enough magnetic field.The secondary winding can create a strong enough spark to jump the spark plug gap .

Primary Ignition Pattern : It's a very good way to check our primary circuit.Also to see firing voltage and burn time.The higher the firing voltage the shorter the burn time is.This uses string theory so as the firing voltage decrease our burn time increases.

Secondary Ignition Pattern : This pettern is a reflection of the primary ignition.It has the same characteristic.The produced by the primary circuit collapsing on itself inducing a voltage very similar to the primary pattern.But the firing voltage is lower. After a snap acceleration, we can see the firing voltage decreases and burns the time that increases which proves the string theory.

In the illustration shown, the horizontal voltage line (primary Sparkline) in the centre of the oscilloscope is at fairly constant voltage of approximately 24 volts, which then drops sharply into what is referred to as the Coil Oscillations. The length of the afore mentioned line is the ‘Spark Duration’ or ‘Burn Time’, which in this particular case is 1.25 ms
The high vertical line at the center of the trace is over 257 volts, this is called the 'induced voltage'.
All these sections of the primary trace are also illustration in individual waveforms listed in the menu. The coil’s High Tension (HT) output will be proportional to the induced voltage. The height of the induced voltage is sometimes referred to as the primary peak volts
A low (0 - 50) voltage scale is required to observe the sparkline and the coil oscillation, while a higher voltage of 0 - 400 volts will require the to check the induced voltage.

Secondary Voltage Patterns

The waveform is an individual secondary High Tension which is the HT picture,that shows one cylinder at a time. This secondary waveform shows the initial voltage.It jumps up to the plug gap, known as the Plug Kv after it shows the length of time that the HT is flowing across the spark plugs and electrode plug gap. This period is known as Burn Time or the Spark Duration.
In the illustration above it can be seen as the horziontal voltage line,Sparkline in the centre of the oscilloscope is at fairly constant voltage.Approximately 5 Kilo volts Kv, which then drops sharply into Coil Oscillations.
The coil Oscillation should display a minimum number of peaks.Both upper and lower is a minimum of 4 - 5 should be seen. A loss of peaks on this Oscillation shows that the coil needs substituting.
The period between the coil oscillation drops down its when the coil is at rest and there is no voltage in the secondary coils.
The drop down is referred to as the Polarity Peak,produces a small Oscillation in the opposite direction.The plug fires voltage.This is due to the initial switching on of the coil’s primary current point.
The voltage within the coil is only released at the correct point of ignition and the HT spark ignites the air and fuel mixture.

Shorted Secondary

 As the cylinder 4 has been grounded to the body the firing voltage decreases because it does not need as much voltage as in a sprark plug but this causes the burn time to increase

 spark tester

  The gap in the tester is smaller than the spark plug gap then firing voltage has decreased , the burn time has increased.