WS8

WS8Primary & Secondary Ignition Patterns

Make Toyota Model 4A-FE Year 1998

PRIMARY VOLTAGE PATTERNS

Firing Voltage 380volts

Burn Voltage  50volts

Burn Time       2.1ms

Dwell Time     3ms

Normal           Yes

 

A simple illustration of the primary waveform tells important detail of the engine firing order. It can easily detect fault due to spark plug, ignition timing and other things. For example it can show one cylinder has a high resistance by having a very high firing voltage. It can tell information such as the burn time, indication of how long it takes to burn the fuel while it’s in the cylinder.

Normal or Abnormal Pattern

Normal pattern indicate the operation result of the magnetic flux passing quickly across the coils primary generate high voltage in the secondary which direct to the engine cylinders relation to the engine speed. Faulty reading could result from low secondary HT causes by low primary voltage due to poor spark performance and cause rich mixture of un-burn fuel in the cylinder.  

Cyl 1	Cyl 2	Cyl 3	Cyl 4	Primary Ignition
400v	400v	400v	400v	Firing Voltage
40v	36.7v	40v	40v	Burn Voltage
105ms	105ms	103ms	107ms	Burn Time
5.86ms	5.86ms	5.86ms	5.86ms	Dwell Time

Here we can look closed to the relationship between firing voltage and burn time. We also see the (dwell time) require charging time for providing good sparks. Weak sparks could cause by short of the dwell time and of course it depends on the engine speed.

These reading emphasize how important of their relation and operation. For example, the higher the firing voltage, the shorted the (burn time).

SECONDARY VOLTAGE PATTERN

 Set up your ignition oscilloscope to view the secondary ignition patterns

Normal Pattern

The secondary waveform shows the initial voltage jump across the plug gap, indicate the length of time that the HT is flowing across the spark plugs. This is known as burn time.

Snap Acceleration Test

Cyl 1	Cyl 2	Cyl 3	Cyl 4	Secondary Ignition
5.2v	5.2v	5.2v	5.2v	Firing Voltage (KV)
1.28ms	1.28ms	1.28ms	1.2ms	Burn Time (ms)
1.8kv	1.8kv	1.8kv	1.8kv	Snap Acceleration

The pattern shown it can be seen that the horizontal voltage line in the centre of the oscilloscope is constant voltage decrease to 1.8 Kilo Volt but the frequency increase. this appear into the Coil Oscillations.

Dissconnect one spark plug wire, and short to the engine with a jumper wirre.

Cyl 1	Cyl 2	Cyl 3	Cyl 4	Secondary Ignition (one cylinder grounded)
5.3kv	5.3kv	5.3kv	5.3kv	Firing Voltage (KV)
1.28ms		1.28ms	1.28ms	Burn Time (ms)

With the shorted ignition pattern the cylinder had a very large plug gap, so the burn time was shorter. Burn time is over 1ms.

Cyl 1	Cyl 2	Cyl 3	Cyl 4	Secondary Ignition (Spark tester on one cylinder)
	19kv	19kv	19kv	Firing Voltage (KV)
1.33ms	0.00	5.2ms	0.00	Burn Time (ms)

The spark tester is on the 1^st cylinder I increased the gap so that it would require more voltage to jump the gap. The picture show the entire operation of four cylinders but this cylinder shows the voltage went off the chart. This indicates the slightest resistance in any wire will ultimately effect the ignition in the cylinder.