WS8 Primmary & Secondary Ignition Patterns

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

Cyl # 1	Cyl # 2	Cyl # 3	Cyl # 4	Primary Ignition
257 volts	257.4 volts	257.4 volts	257.4 volts	Firing Voltage
24.1 volts	24.1 volts	24.1 volts	24.1 volts	Burning Voltage
1.25 ms	1.26 ms	1.25 ms	1.25 ms	Burn Time
6.70 ms	6.40 ms	6.70 ms	6.70 ms	Dwell Time

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 centre 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.

20 Secondary Voltage Patterns



Cyl # 1	Cyl # 2	Cyl # 3	Cyl # 4	Secondary Ignition
5.2 KV	5.2 KV	5.2 KV	5.2 KV	Firing Voltage ( KV)
1.28 ms	1.28 ms	1.28 ms	1.28 ms	Burn Time (MS)
2.8 KV	2.8 KV	2.8KV	2.8 KV	Snap Acceleration

The waveform is an individual secondary High Tension (HT) picture that can be observed one cylinder at a time. This secondary waveform shows the initial voltage to jump the plug gap, know as the ‘Plug Kv’ then shows the length of time that the HT is flowing across the spark plugs electrode plug gap. This time is referred to as either the ‘Burn Time’ or the ‘Spark Duration’.
In the illustration shown it can be seen that the horziontal voltage line (Sparkline) in the centre of the oscilloscope is at fairly constant voltage of approximately 5 Kilo volts (Kv), which then drops sharply into what is referred to as the ‘Coil Oscillations’.
The coil oscillation should display a minimum number of peaks (both upper and lower) and 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 and the next ‘drop down’ is when the coil is at rest and there is no voltage in the coils secondary.
The ‘drop down’ is referred to as the ‘Polarity Peak’ and produces a small oscillation in the opposite direction to the plug firing voltage. This is due to the initial switching on of the coil’s primary current.
The voltage within the coil is only released at the correct point of ignition and the HT spark ignites the air/fuel mixture.

Waveform of secondary ignition , disconnect one spark plug and short to the engine;

The plug firing voltage is the voltage required to jump and bridge the gap at the plug’s electrode. Commonly known as the ‘Plug Kv’ (Kilo Volts).
The plug Kv’s will be increased by:
Large plug gaps
A large rotor air gap
A break in a plug lead
A break in the king lead
Worn spark plugs
A lean mixture
Rotor to reluctor misalignment
We can see on that picture waveform , the plug wich i disconnected the voltage is increased to 19 KV .A high resistance in the High Tension (HT) lead or the coil lead will not alter the plug Kv (however an increase in sparkline Kv will be evident). An open circuit lead will increase both the plug Kv and the sparkline Kv

At next vidio we can see the big gap of sprk plug , big gap need high burn vltage but short burn voltage .