WS8 Primary & Secondary Ignition Patterns

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

Warning : Ignition coils create high voltage . It can be dangerous , so avoid getting too close to ignition parts when engine is running . Make your connections when the engine is off , and then keep your distance when the engine is running . Even some primary voltage is high enough to stop a "Pacemaker".

Also : Do not run engines with secondary ignition HT leads " open circuit " . Make sure they are grounded to engine through a spark plug , grounding wire , or spark tester.

If you have problems with task , see you lecturer for help.

1.0 Primary Voltage Patterns
1.1 Set up a lab scope or ignition oscilloscope to view the primary ignition pattern ( in parade or display mode ) on your lab scope , with the engine warmed up and idling.
1.2 Record the average Firing Voltage ( or " step up voltage ) for each cylinder in the chart below. Some variation is normal , just pick the average . If you don't understand what this is , review the resource information available.
1.3 Record the average Burn Voltage for each cylinder in the chart below .
1.4 Record the average Burn Time in milliseconds for each cylinder in the chart below .
1.5 Record the average Dwell Time for each of the cylinders in the chart below . What unit of measurement are you using to measure the dwell time ?    MS
1.6 Are all these primary ignition voltage reading normal ? Yes
please discuss what is normal or abnormal about this pattern and what causes it ?
This patten is normal as it shows the dwell or charge time , the firing KV , the burn time and the stabalizing voltage.
Cyl1               Cyl2               Cyl3               Cyl4               Primary Ignition
250V             250V              250V             250V              Firing Voltage
53V               52V                50V               54V                Burn Voltage
1.1ms            1.0ms              1.0ms            1.1ms              Burn Time
5.8ms            5.6ms              5.7ms            5.7ms              Dwell Time
1.7 Draw or photograph the Primary Ignition oscilloscope parade pattern from your scope into the box below . Do it carefully and show the detail you need to see for diagnosis . Record voltage and time scales.

1.8 Discuss what the primary display or parade pattern emphasizes for diagnosis . What can it help you see?
That can help me see whether there is a long enough dwell time , whether the firing KV is high enough , also we can see the burn time
1.9 Some scopes have the facility to use raster or stacked display . How could this help you to diagnose a fault . What can you see more clearly?
I can see at more than one voltage wave  pattern at the time. This can help me to easily pin point faults in the primary and secondary ignition.

2.0 Secondary Voltage Patterns
2.1 Set up your ignition oscilloscope or lab scope to view the secondary ignition patterns on your lab scope , with the engine warmed up and idling . ( Use parade mode or individual mode on each different cylinder , depending on scope available .)
2.2 Record the average Firing Voltage ( or "Step Up voltage ) for each cylinder in the chart below . Some variation is normal , just pick the average . If you don't understand what this is , review the resource information at the back of this worksheet.
2.3 Record the average Burn Time for each cylinder in the chart below .
Are all these secondary ignition voltage reading normal ? Yes
Discuss what is happening in the pattern and what it is telling you about the ignition system .
This shows the dwell time of the secondary ignition, it's also shows the firing voltage for the spark and the burn time for the spark.
2.5 Do a Snap Acceleration  ( don't damage the engine by revving too high or for too long ) and record in the chart below how high the Firing voltage ( KV ) went under Snap Acceleration .
Cyl1               Cyl2               Cyl3               Cyl4               Secondary Ignition
6KV              6KV               6KV              6.5KV            Firing Voltage
1.8ms            1.7ms              2.0ms            1.4ms              Burn Time
13KV           13KV              13KV            13KV             Snap Acceleration
2.6 Are all these Snap Acceleration secondary ignition voltage readings normal ? Yes
Discuss whta is happening and what the pattern is telling you.
Yes these reading were normal as the graph shows , the firing KV increase as the engine RPM increase.
2.7 Draw or photograph the Secondary Ignition lab scope pattern while idling from your scope in to the box below . Do it carefullt and show the detail you need to see for diagnosis

2.8 If you can stfely do this , ( with the engine stopped ), gently disconnect one spark plug wire , and short to the engine with a jumper wire . Which cylinder number did you short ? 4
2.9 Start the engine and let it dile ( for only a short time .) Record the new Firing Voltage and Burn Time for all the cylinders in the chart below.
Cyl 1               Cyl 2               Cyl 3               Cyl 4               Recondary Ignition
6KV                6KV               6KV               4KV                Firing Voltage ( KV )
2.8ms              2.2ms              2.0ms             3.9ms               Burn Time      ( ms )
2.10 Draw or photograph the shorted Secondary Ignition waveform you see now on your scope.

2.11 Discuss what is happening in the shorted ignition pattern and how the ignition pattern tells you what it is happening in the ignition system .
The shorted cyl has a much lower firing voltage and a much longer burn time as there is no force required to jump the spark plug gap to earth
2.12 Remove the ground wire and attach the spark plug wire back on the engine so it is normal again . Run the engine a bit to clear the spark plug .
2.13 Stop the engine and attacg a spark tester to another spark plug wire . Start the engine and let it idle ( for only a short time ) . Record the new Firing Voltage and Burn Time for all the cylinders in the chart below.
Cyl 1               Cyl 2               Cyl 3               Cyl 4               Secondary Ignition
7KV               13KV             6KV                7KV                Firing Voltage
1.5ms             1.3ms              2.1ms              1.7ms               Burn Time
2.14 Draw or photograph the spark tester Secondary Ignition waveform you see now on your scope . Show the detail that is necessary for accurate diagnosis . Include time and voltage

2.15 Stop the engine , remove the spark tester ( be gentle ) , replace the spark plug wire , and run the engine to clear the spark plug . The engine should be back to normal now . If not , tell your lecturer.
 2.16 Discuss what happens to the ignition waveform when the spark tester is attached to the spark plug wire . What does it tell you about the igntion system .
On the spark plug with the spark tester , the firing voltage was much higher as there is a larger gap to jump . That means there is less energy after the spark has jumped the gap so there is shorter burn time .
2.17 Removw the spark tester carefully , and put everything back together on the engine . Engine runs fine ?Yes